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Itampolin A, a natural brominated tyrosine alkaloid isolated from the sponge Iotrochota purpurea, has been shown to have good inhibitory effects in lung cancer cells as a p38α inhibitor. A simple, sensitive, and reliable ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) method has been established, validated, and applied to the study of the pharmacokinetics and tissue distribution of itampolin A following intragastric and intravenous administration. Itampolin A and theophylline (internal standard, IS) were extracted by the simple protein precipitation technique using methanol as the precipitating solvent. Chromatographic separation was achieved by using the optimized mobile phase of a 0.1% formic acid aqueous solution and acetonitrile in the gradient elution mode. Itampolin A and IS were detected and quantified using positive electrospray ionization in the multiple reaction monitoring mode with transitions of m/z 863.9 → 569.1 for itampolin A and m/z 181.1 → 124.1 for IS, respectively. The assay exhibited a linear dynamic range of 1–1600 ng/mL for itampolin A in biological samples and the low limit of quantification was 1 ng/mL. Non-compartmental pharmacokinetic parameters indicated that itampolin A was well-absorbed into the systemic circulation and rapidly eliminated after administration. The apparent distribution volume of itampolin A was much higher after intragastric administration than that after intravenous administration. A tissue distribution study showed that itampolin A could be detected in different tissues and maintained a high concentration in the lung, which provided a material basis for its effective application in lung cancer. The pharmacokinetic process and tissue distribution characteristics of imtapolin A were expounded in this study, which can provide beneficial information for the further research and clinical application of itampolin A. [ABSTRACT FROM AUTHOR]

SIPI6398 is a novel anti-schizophrenia agent with a new mechanism of action and demonstrates better target selectivity and safety compared to its competitors. However, few in vivo studies on the pharmacokinetics and bioavailability of SIPI6398 have been performed. A rapid and simple ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) approach was developed for accurate quantification of SIPI6398 in rat plasma. A simple protein precipitation of acetonitrile-methanol (9 : 1, v/v) was used to treat plasma. Chromatography was performed on a UPLC HSS T3 column (50 mm × 2.1 mm, 1.8 μm) at a flow rate of 0.4 ml/min. The mobile phase consisted of acetonitrile-water (with 0.1% formic acid) and gradient elution was used, and the elution time was 4 minutes. Quantitative analysis was performed using electrospray ionization (ESI) in positive ion detection mode with multiple reaction monitoring (MRM) mode. To evaluate the pharmacokinetics and bioavailability, SIPI6398 was administered to rats in two different ways: oral (4 mg/kg) and intravenous (2 mg/kg) administration. The calibration curve for the UPLC-MS/MS approach shows excellent linearity in the range of 1–2000 ng/mL with an r value above 0.99. The precision, accuracy, recovery, matrix effect, and stability results all meet the criteria established for biological analytical methods. The UPLC-MS/MS method was successfully applied it to pharmacokinetics study of SIPI6398. The bioavailability of SIPI6398 was calculated to be 13.2%. These studies have the potential to contribute towards a more comprehensive comprehension of the pharmacokinetics and bioavailability of SIPI6398. [ABSTRACT FROM AUTHOR]

A pinanamine‐based analog, (1R,2R,3R,5S)‐N‐((3‐cyclopropylthiophen‐2‐yl)methyl)‐2,6,6‐trimethylbicyclo[3.1.1]heptan‐3‐amine (M090) was synthesized and demonstrated with anti‐influenza activity to overcome the multi‐drug resistance. Herein, a rapid and robust liquid chromatography‐tandem mass spectrometry method was developed and validated to quantify M090 in rat plasma. With simple protein precipitation by methanol, the separation of M090 was performed on a Waters BEH‐C18 column (2.1 × 100 mm, 1.7 μm) by gradient elution at 0.4 mL/min with mobile phases consisting of water containing 0.1 % formic acid (phase A) and methanol (phase B). M090 and clenbuterol (internal standard) were detected using multiple reaction monitoring in positive electrospray ionization mode with transitions of m/z 290.3→137.0 and m/z 277.0→203.0, respectively. The method was validated over a linear range of 1.0–2400 ng/mL with a regression coefficient of 0.9974 and no endogenous interference. The intra‐ and inter‐batch precisions were within 8.29% and accuracy ranged from 100.3% to 108.1% for M090. The validated method was utilized to evaluate the in vitro metabolic stability and in vivo pharmacokinetics of M090 in rats. [ABSTRACT FROM AUTHOR]

Sanguisorba officinalis L. possesses detoxifying, analgesic, and hemostatic properties. After charred processing, S. officinalis exhibits significantly enhanced medicinal effects. Currently, most pharmacokinetic studies focus on the chemical constituents of unprocessed S. officinalis. There is limited research on the comparison of chemical constituents before and after processing. This study established a pharmacokinetic method using ultra‐high‐performance liquid chromatography‐tandem mass spectroscopy (UHPLC‐MS/MS) to simultaneously determine the levels of four tannin compounds in rat plasma. In negative ion mode, MS/MS detection was performed using an electrospray ionization source. Chromatographic separation was performed using WATERS ACQUITY HSS T3 column (2.1 × 100 mm, 1.8 µm) with a gradient elution of water and acetonitrile as the mobile phase. The pharmacokinetic results indicate that all four compounds reached peak concentrations within 2 h, demonstrating rapid absorption into the bloodstream within the gastrointestinal tract. Notably, the absorption was generally faster in the charred compound of S. officinalis after processing. These four compounds exhibited slower elimination in rat plasma, while in S. officinalis charcoal, the compounds were eliminated more rapidly. The pharmacokinetic results have revealed the pharmacokinetic characteristics of the four analytes in rat plasma which provides valuable reference information for further investigating the in vivo absorption process of S. officinalis after processing. [ABSTRACT FROM AUTHOR]

A novel leucine carbamate prodrug (3-L) has been synthesized to improve the low oral bioavailability of cycloicaritin. To assess the pharmacokinetic properties of the prodrug, a selective, sensitive and reliable liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for the simultaneous determination of cycloicaritin and its carbamate prodrug 3-L in rat plasma with daidzein as internal standard was developed and validated. Ethanoic acid was added to plasma samples to maintain the stability of the prodrug. The samples were prepared employing a liquid–liquid extraction (LLE) method using tert-butyl methyl ether in a low plasma sample volume of 25 μL, and then separated on an ACE Excel 2 C18-Amide column (50 mm × 2.1 mm, 2 μm) by gradient elution at a flow rate of 0.4 mL min−1. A triple quadrupole tandem mass spectrometer system with a positive ESI interface was used for quantification in multiple reaction monitoring (MRM) mode. Cycloicaritin and 3-L both showed excellent linearity over the concentration range of 1–2000 ng mL−1 (r ≥ 0.995), with a lower limit of quantification of 1 ng mL−1. The accuracy varied from −5.2% to 14% for all analytes, and the intra- and inter-day precision was less than 14% across quality control levels. The method described herein was successfully applied to the pharmacokinetic study of orally administered 3-L in rats. [ABSTRACT FROM AUTHOR]

An ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of tenacissoside G, tenacissoside H, and tenacissoside I in rat plasma. The rat plasma was treated with liquid-liquid extraction using ethyl acetate. The determination was performed on the UPLC HSS T3 column (50 mm × 2.1 mm, 1.8 μm) with a mobile phase consisting of acetonitrile-water (containing 0.1% formic acid) and gradient elution at a flow rate of 0.4 mL/min. Electrospray (ESI) positive ion mode detection and multireaction monitoring (MRM) quantitative analysis were performed. A total of 36 rats were given tenacissoside G, tenacissoside H, and tenacissoside I, respectively, orally (5 mg/kg) and intravenously (1 mg/kg), with 6 rats in each group, to evaluate the pharmacokinetic difference of tenacissoside G, tenacissoside H, and tenacissoside I in rats. The calibration curves showed good linearity in the range of 5–2000 ng/mL, where r was greater than 0.99. The results of precision, accuracy, recovery, matrix effect, and stability met the requirements of biological sample detection methods. The established UPLC-MS/MS method was successfully applied to pharmacokinetic studies of tenacissoside G, tenacissoside H, and tenacissoside I, and the bioavailability was 22.9%, 89.8%, and 9.4%, respectively. [ABSTRACT FROM AUTHOR]

Lavender (Lavandula angustifolia Miller or Lavandula officinalis Chaix) is an ethnopharmacological plant commonly known as English lavender. Linalool and linalyl acetate are putative phytoactives in lavender essential oil (LEO) derived from the flower heads. LEO has been used in aroma or massage therapy to reduce sleep disturbance and to mitigate anxiety. Recently, an oral LEO formulation was administered in human clinical trials designed to ascertain its anxiolytic effect. However, human pharmacokinetics and an LC–MS/MS method for the measurement of linalool are lacking. To address this deficiency, a rapid and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the analysis of linalool in human serum. Prior to the analysis, a simple sample preparation protocol including protein precipitation and liquid–liquid extraction of serum samples was created. The prepared samples were analyzed using a C18 reversed-phase column and gradient elution (acetonitrile and water, both containing 0.1% formic acid). A Waters Xevo TQ-S tandem mass spectrometer (positive mode) was used to quantitatively determine linalool and IS according to transitions of m/z 137.1→95.1 (tR 0.79 min) and 205.2→149.1 (tR 1.56 min), respectively. The method was validated for precision, accuracy, selectivity, linearity, sensitivity, matrix effects, and stability, and it was successfully applied to characterize the oral pharmacokinetics of linalool in humans. The newly developed LC–MS/MS-based method and its application in clinical trial serum samples are essential for the characterization of potential pharmacokinetic and pharmacodynamic interactions. [ABSTRACT FROM AUTHOR]

A preliminary study has shown that 3, 8-Di-O-methylellagic acid 2-O-glucoside (DMAG), an ellagic tannin from Sanguisorba officinalis L., has the potential in relieving thrombocytopenia. However, there is a lack of information on the pharmacokinetics of DMAG in thrombocytopenia rats. Therefore, we aimed to establish a simple, rapid, and sensitive UHPLC-MS/MS method for quantifying DMAG and study its pharmacokinetic behavior in this study. DMAG and hispidulin (internal standard, IS) were separated on an Acquity Shim-pack GIST column using 0.1% formic acid in water and acetonitrile as the mobile phase with a total run time of 5 min and gradient elution at a flow rate of 0.3 mL/min. The recovery and matrix effects of DMAG were within 94.85%–100.40% and 94.55%–102.46%, respectively. The intraday RSD and interday RSD were between 3.31% and 13.19%, accuracy RE was ≤6.69%, and stability RSD changes were 3.38%–8.78%. As for intragastric administration, with shortened Tmax (3.00 vs. 2.16 h), Cmax (25.67 vs. 35.38 ng/mL) was added for a 2 mg/kg dose after the establishment of the thrombocytopenia rat model. Relative to normal rats treated with 4 mg/kg, in thrombocytopenia rats treated with the same dose, Cmax (49.13 vs. 67.78 ng/mL), AUC(0–t) (234.60 vs. 318.17 ng·h/mL), and AUC(0–∞) (322.74 vs. 498.57 ng h/mL) increased, MRT (18.15 vs. 26.32 h) prolonged, Tmax (3.00 vs. 2.33 h) shortened, and CL/F (12746.50 vs. 8093.50 mL/h/kg) reduced. As for intravenous administration, Cmax (1679.54 ng/mL), AUC(0–t) (589.02 g·h/mL), and AUC(0–∞) (605.58 g·h/mL) were significantly increased in thrombocytopenia rats than that in normal rats (743.76 ng/mL for Cmax, 242.46 g·h/mL for AUC(0–t), and 245.19 g·h/mL for AUC(0–∞)). Vz/F and CL/F were remarkably decreased from 343196.86 to 194659.43 mL/kg for Vz/F and 8236.18 to 3326.01 mL/h/kg for CL/F with the model establishment, respectively. Overall, we successfully developed a reliable UHPLC-MS/MS method for determining DMAG levels in rat plasma. The pharmacokinetic difference could be attributed to the pathological state of the thrombocytopenia rats, which may affect the absorption, distribution, metabolism, and excretion of DMAG. These findings lay the foundation for further evaluating the clinical efficiency and safety of DMAG in the treatment of thrombocytopenia. [ABSTRACT FROM AUTHOR]

Nalbuphine was a semisynthetic opioid analgesic widely used in the treatment of both acute and chronic pain. We developed and validated a rapid, simple and sensitive method by ultra-performance liquid chromatography–tandem mass spectrometry (MS/MS) for the simultaneous quantitation of nalbuphine in human plasma, and we reported the pharmacokinetic features of patients during general anesthesia for abdominal surgery. Sample separation was achieved on a Kinetex Phenyl-Hexyl column (50 × 2.1 mm, 1.7 μm) after simple protein precipitation with acetonitrile. The mobile phase was composed of acetonitrile and 3 mM of ammonium acetate aqueous solution with 0.1% formic acid. Gradient elution was used in 4.5 min with a flow rate of 0.5 mL/min at 40°C. MS detection using AB Sciex QTRAP 5500 mass spectrometer was characterized by electrospray ionization for positive ions in multiple reaction monitoring mode. Quantitative ion pairs were m/z 358.4 → 340.1 for nalbuphine and m/z 340.0 → 268.3 for nalmefene, which were used as the internal standard (IS). The calibration curves showed good linearity (r 2>0.99) over concentration range of 0.1–500 ng/mL. The intra-and inter-batch precisions were within 10.67%, and accuracy ranged from 94.07 to 105.34%. The IS–normalized matrix factors were 1.02–1.03 with RSD% (≤5.82%). The recoveries ranged from 101.09 to 106.30%. In conclusion, a rapid, simple, sensitive and economical analytical method was developed and validated to detect the concentration in plasma samples obtained from patients receiving nalbuphine intravenous injection and was successfully applicated to human pharmacokinetic studies of nalbuphine. [ABSTRACT FROM AUTHOR]

Plinabulin, a new antitumor drug developed from marine natural products that targets microtubules in cancer cells, is currently being tested in a phase III clinical study. Plinabulin has been clinically proven to be effective on leukopenia. However, to our knowledge, there are no reports investigating the pharmacokinetics of plinabulin in individuals with leukopenia and healthy individuals. In this study, we developed a rapid and sensitive UHPLC-MS/MS method for the detection of plinabulin for the first time. Using a novel cyclophosphamide-induced leukopenia model, we investigated the differences in the pharmacokinetic characteristics of plinabulin between rats with leukopenia and normal rats. Plinabulin and propranolol (IS) peaks were separated by gradient elution for a total run time of 5 min. The methodological validation showed a good accuracy (101.96–109.42%) and precision (RSD ≤ 5.37%) with the lower limit of quantification at 0.5 ng/mL. The recovery of plinabulin was between 91.99% and 109.75% (RSD ≤ 7.92%). The values of the area under the plasma concentration-time curve (AUC0-t) for leukopenia groups and control groups at doses of 0.5 mg/kg, 1 mg/kg, and 3 mg/kg were 148.89 ± 78.74 h·μg/L and 121.75 ± 31.56 h·μg/L; 318.15 ± 40.00 h·μg/L and 272.06 ± 42.85 h·μg/L; and 1432.43 ± 197.47 h·μg/L and 1337.12 ± 193.56 h·μg/L; respectively. The half-lives (t1/2s) of plinabulin were 0.49–0.72 h for leukopenia groups and 0.39–0.70 h for control groups at three doses, and the clearance rates (CLs) of plinabulin were 2.13–3.87 L/h/kg for leukopenia groups and 2.29–4.23 L/h/kg for control groups. Pharmacokinetic results showed that there was no significant pharmacokinetic difference between the normal group and the leukopenia group. Based on the power model, plinabulin exhibits a lack of dose proportionality over the dose range of 0.5–3 mg/kg after intravenous administration. This study provides guidance for the development of plinabulin as a potential candidate for the treatment of chemotherapy-induced leukopenia. [ABSTRACT FROM AUTHOR]

For most cancers, drugs in combination with chemotherapy is a promising way. Dasatinib in combination with paclitaxel can potentially be used to overcome triple‐negative breast cancer. In this work, we established an liquid chromatography‐tandem mass spectrometry method for the simultaneous determination of dasatinib and paclitaxel. Tert‐Butyl methyl ether was used to extract paclitaxel, dasatinib, and docetaxel (Internal standard). The study used multiple reaction monitoring mode with electrospray ionization. Monitoring ion pairs for paclitaxel and dasatinib was m/z 876.2→308.2 and m/z 488.3→401.1, respectively. The chromatographic separation was performed on a Hedera ODS‐2 column (150 × 2.1 mm, 5 μm; Hanbon Science and Technology, China) maintained at 40°C. The mobile phase was acetonitrile containing 0.3% formic acid (B) and water (A). The gradient elution procedure was used: 0–1 min, 70% B; 1.1–4 min, 90% B; 4.1–7 min, 70% B. The results satisfied the requirements of biological sample determination. The liquid chromatography‐tandem mass spectrometry method was successfully applied to the pharmacokinetic study of rats. The rats were simultaneously injected with dasatinib and paclitaxel by tail vein. What is more, this presented method could provide technical support for the clinical combination of these two drugs. [ABSTRACT FROM AUTHOR]

Y-99, a promising first-in-class diuretic, is a novel urea transporter inhibitor with oral diuretic activity. However, little is known about the pharmacokinetic profiles of Y-99 in experimental animals. In this study, a method of quantitative determination of Y-99 in rat plasma based on high-performance liquid chromatography–tandem mass spectrometry was developed and validated in selectivity, linearity, recovery and matrix effect, accuracy and precision, stability, carry-over and dilution integrity. Chromatographic separation was conducted on an ACQUITY BEH C18 column (2.1 mm × 50 mm, 1.7 μm) with gradient elution at a 0.3 mL/min flow rate after protein precipitation. Mass spectrometry was performed by a positive electrospray ionization mass spectrometer in multiple reaction monitoring mode. The method showed standard-compliant linearity (1–1,000 ng/mL, r  = 0.9991). The intra-day and inter-day accuracy (relative error < 11.2%) and precision (coefficient of variation <8.4%) were within acceptable criteria. The recovery and matrix effects were 97.3–110.7% and 103.7–107.5%, respectively. The stability, dilution integrity and carry-over of the method were also within the acceptable criteria. Pharmacokinetic profiles of Y-99 in rats were first investigated using this method, which was vital for developing novel diuretics without electrolyte imbalance targeting urea transporters. [ABSTRACT FROM AUTHOR]

Because of its greater binding affinity and longer half-life than native glucagon-like peptide-1 (GLP-1), the GLP-1 receptor agonist lixisenatide is commonly used to treat type 2 diabetes mellitus. This study aimed to establish a simple and robust liquid chromatography–tandem mass spectrometry (LC–MS/MS) approach for lixisenatide for in vivo pharmacokinetic investigation. Methanol-based protein precipitation with formic acid was exploited for plasma sample extraction, using esomeprazole as the internal standard. Gradient elution with 0.1% formic acid in distilled water and acetonitrile was utilized for chromatographic separation. Mass spectrometry was used to monitor the MRM transition at m/z 810.8 → 129.2 for lixisenatide. In rat plasma, lixisenatide had a lower limit of quantification of 10 ng/mL. The LC–MS/MS was applied to describe the pharmacokinetics of lixisenatide in rats following intravenous and subcutaneous dosing. The average half-life of lixisenatide was 0.37 ± 0.06 h after intravenous injection. The estimated subcutaneous bioavailability of lixisenatide was 2.17%. This LC–MS/MS analysis might be relevant in future research to create novel dosage formulations of lixisenatide and other GLP-1 receptor agonists with optimal therapeutic effectiveness. [ABSTRACT FROM AUTHOR]

Liraglutide is a glucagon-like peptide-1 (GLP-1) analog that has been utilized for the treatment of type 2 diabetes mellitus. Liraglutide at a higher dose also shows beneficial effects in weight loss, which prompted its widespread use as an anti-obesity drug. The potential of liraglutide to treat Alzheimer's disease and cognitive impairment has also been suggested. Nevertheless, the pharmacokinetics of liraglutide, including its distribution to the brain, has not been fully characterized. Therefore, this study aimed to develop a simple and sensitive bioanalytical method using liquid chromatography–tandem mass spectrometry (LC–MS/MS) and determine the pharmacokinetics and brain distribution of liraglutide in rats. Liraglutide in the rat plasma and brain tissue homogenates was extracted by protein precipitation using methanol. A gradient elution profile was used for chromatographic separation with mobile phases comprising 0.3% formic acid in water and 0.3% formic acid in acetonitrile. The mass spectrometry was operated in the positive electrospray ionization with multiple reaction monitoring mode. The lower limit of quantification of the present LC–MS/MS was 1 ng/mL in the plasma and 2 ng/mL in the brain tissue. Following intravenous injection (0.05 mg/kg, n = 5), plasma concentrations of liraglutide decreased monoexponentially with an average half-life of 3.67 h. The estimated absolute bioavailability of liraglutide after subcutaneous injection was 13.16%. Brain distribution of liraglutide was not significant, with the tissue-to-plasma partition coefficient (Kp) of liraglutide less than 0.00031. However, the concentrations of liraglutide were significantly different in the different brain regions following IV injection. In the brain, liraglutide concentrations were the highest in the hypothalamus, followed by the cerebellum and cerebrum. The present LC–MS/MS assay and the pharmacokinetic results may be helpful to understand better the effect of liraglutide in the brain for further preclinical and clinical studies of liraglutide. [ABSTRACT FROM AUTHOR]

Objective: A sensitive and rapid ultra‐high‐performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method was successfully applied to the determination of 10 alkaloids in beagle dog plasma following a single oral dose of Xiatianwu capsules and enteric‐coated capsules, with theophylline serving as the internal standard (IS). Methods: Plasma samples were preprocessed using liquid–liquid extraction (LLE) with ethyl acetate ahead to separation using a gradient elution procedure on a Waters ACQUITY UPLC HSS T3 column (1.8 μm, 100 × 2.1 mm). The mobile phase was composed of 0.1% formic acid solution and acetonitrile at the flow rate of 0.3 ml/min. Multiple reaction monitoring (MRM) was used to determine the analytes in the positive ion mode. Results: The calibration curves for 10 analytes demonstrated a high degree of linearity (r ≥ 0.9920). The lower limit of quantification (LLOQ) values for 10 alkaloids were all more than 1.074 ng/ml, and matrix effects varied from 94.25% to 106.15%. The mean extraction recovery of quality control samples at low (LQC), medium (MQC) and high (HQC) concentrations, as well as IS, was all more than 76.60%. The intra‐day and inter‐day precision (RSD) also satisfied the requirement. Simultaneously, the variation of assay accuracies (RE) was between 13.05% and 9.38%. Conclusion: The test was validated in accordance with regulatory bioanalytical guidelines and was found to be suitable for use in a pharmacokinetic investigation of these compounds in beagle dogs after oral administration of Xiatianwu general capsules and enteric‐coated capsules. The Cmax of 10 alkaloids ranged from 52.61 to 192.46 ng/ml after oral administration of Xiatianwu capsules, and from 67.50 to 247.36 ng/ml. The Tmax was between 0.59 and 1.33 h of Xiatianwu capsules, and between 1.08 and 2.00 h of enteric‐coated capsules. The t1/2 ranged from 3.18 to 7.47 h of general capsules, and from 6.01 to 11.36 h. AUC0‐t ranged from 181.06 to 722.74 ng·h/ml of Xiatianwu capsules, and from 275.03 to 884.17 ng·h/ml of enteric‐coated capsules. The Cmax of enteric‐coated capsules were significantly increased except for tetrahydropalmatine and berberine. Tmax of general capsules were less than 1 h, and of enteric‐coated capsules were less than 2 h. The t1/2 of dehydrocorydaline, palmatine, tetrahydrojatrorrhizine, jatrorrhizine and coptisine in enteric‐coated capsules was longer than that in ordinary capsule. The AUC0‐t and AUC0‐∞ of bicuculline, dehydrocorydaline, protopine, magnoflorine, tetrahydrojatrorrhizine, jatrorrhizine, berberine and coptisine were all significantly higher in enteric‐coated capsules. [ABSTRACT FROM AUTHOR]

Butachlor is an aromatic amide compound that plays a role as a herbicide, a xenobiotic, and an environmental contaminant. The aim of this work was to develop a highly selective and sensitive ultra‐performance liquid chromatography‐tandem mass spectrometry method based on the tandem mass spectrometry cubed technique to determine butachlor in a biological matrix. Butachlor and internal standard acetochlor were separated on a Waters Acquity ultra‐performance liquid chromatography BEH C18 column (2.1 × 50 mm, 1.7 μm) with gradient elution using 0.1% formic acid aqueous solution (A) and acetonitrile (B) as mobile phases. The transitions selected for tandem mass spectrometry cubed quantitative analysis in positive ion mode were: for butachlor, mass‐to‐charge ratio 312.2→238.1→162.1; for acetochlor, mass‐to‐charge ratio 270.1→224.0→148.1. The total running time for each sample was 5.5 min. The ultra‐performance liquid chromatography‐tandem mass spectrometry cubed method showed a linear relationship (R2 ≥ 0.995) in the concentration range of 0.5–100 ng/ml. The intra and interday accuracies are within the range of ‐10.6%–4.3% and precisions are between 4.48% and 13.14%. The novelty of the method is the use of tandem mass spectrometry cubed scanning mode, which improves selectivity and sensitivity. The results indicated that butachlor was cellular toxic. The safety of butachlor should be considered when it is used as a herbicide. [ABSTRACT FROM AUTHOR]

A rapid, sensitive, selective, and accurate HPLC–MS/MS method was developed and validated for the simultaneous determination of chlorogenic acid, naucleactonin C, khaephuoside A 3,4-dimethoxyphenyl-1-O-β-apiofuroseyl(1 ⟶ 2)-β-D-glucopyranoside in rat plasma and tissues after oral administration of Nauclea officinalis extracts. Chloramphenicol was used as an internal standard (IS). The plasma and tissue samples were extracted by protein precipitation with methanol-ethyl acetate (1 : 1, v/v) including 0.1% (v/v) formic acid. The chromatographic separation was achieved by using an C18 column with gradient elution using mobile phase, which consisted of 0.1% formic acid water (A) and acetonitrile (B) and the flow rate of 0.8 mL/min. Mass spectrometric detection was performed in multiple reaction monitoring (MRM) mode utilizing electrospray ionization (ESI) in negative mode. The developed method exhibited good linearity (determination coefficients, R2 ≥ 0.9849), and the lower limits of quantification were 2, 5, 5, and 25 ng/mL for chlorogenic acid, naucleactonin C, khaephuoside A, and 3,4-dimethoxyphenyl-1-O-β-apiofuroseyl(1 ⟶ 2)-β-D-glucopyranoside. The intraday and interday precisions (relative standard deviation, RSD) were less than 12.65%, while the accuracy was ranged from 86.31 to 114.17%. The recovery rate were 51.85–97.06%, 75.99–106.68%, 77.46–105.35%, and 68.36–103.75% for chlorogenic acid, naucleactonin C, khaephuoside A, and 3,4-dimethoxyphenyl-1-O-β-apiofuroseyl(1 ⟶ 2)-β-D-glucopyranoside the matrix effects were 50.17–116.62%, 86.75–115.99%, 45.79–87.44%, and 51.60–92.34% for chlorogenic acid, naucleactonin C, khaephuoside A, and 3,4-dimethoxyphenyl-1-O-β-apiofuroseyl(1 ⟶ 2)-β-D-glucopyranoside in different matrix. The developed method was successfully applied to a pharmacokinetic study and tissue distribution of four compounds in rats after oral administration of Nauclea officinalis extracts. [ABSTRACT FROM AUTHOR]

Physalin A is a promising natural product with excellent anti-inflammatory and anti-tumor activities. However, the pharmacokinetic profile of physalin A is still unclear. In this study, a rapid and sensitive analytical method based on LC–MS/MS for the quantitation of physalin A in rat plasma with special consideration to its chemical stability was developed and validated. To avoid the degradation of physalin A, the separation of plasma was conducted at 4 °C directly after the blood samples were collected. Meanwhile, plasma samples were immediately precipitated with acetonitrile containing tolbutamide (internal standard, IS) and the pH of the supernatant was adjusted to 1.5 with formic acid. Chromatographic separation of physalin A and IS was achieved on an ACQUITY UPLC BEH-C18 column (2.1 × 50 mm, 1.7 μm) using 0.1% formic acid and acetonitrile as mobile phase delivered at 0.3 mL/min in a gradient elution mode. Physalin A and IS were detected through negative ion electrospray ionization in multiple reaction monitoring (MRM) mode. The MS/MS ion transitions for physalin A and IS were m/z 525.1–148.9 and m/z 269.8–169.9, respectively. The developed method showed good linearity over the range of 2.00–400 ng/mL. This method was successfully applied to the pharmacokinetic study of physalin A in rats following its intragastric administration and the findings were beneficial for future studies of physalin A. [ABSTRACT FROM AUTHOR]

The total flavonoids of Desmodium styracifolium are the flavonoid extracts purified from Desmodii Styracifolii Herba, which has conventionally been used for treating urolithiasis in China. In this study, a sensitive and simple liquid chromatography‐tandem mass spectrometry method was developed to simultaneously determine five active components of the extracts in rat plasma. Chromatographic separation of the analytes (schaftoside, vicenin‐1, vicenin‐2, vicenin‐3, and isovitexin) was performed on an ACQUITY UPLC HSS T3 Column under gradient elution conditions. The calibration curves were linear over ranges from 0.5 to 100 ng/ml for schaftoside, vicenin‐1, vicenin‐2, and vicenin‐3, and 0.2–20 ng/ml for isovitexin. The relative standard deviation of intra‐ and inter‐day precisions were ≤6.8% and ≤8.3%, respectively, and the accuracies (relative error) were within ±7.6%. The recoveries of the analytes ranged between 97.3% and 100.3%, and the matrix effects ranged from 98.6% to 113.8%. The method was successfully applied to the pharmacokinetic studies of the five active ingredients of Desmodium styracifolium, for the first time, in both normal and urolithiasis model rats. Results revealed that the plasma levels of these components were significantly increased under the pathological state. This study provided valuable information facilitating the clinical investigation of this medicine. [ABSTRACT FROM AUTHOR]

• Atenolol and metoprolol are the preferred drugs in the treatment of hypertension and heart failure. • Importance of assessing intestinal absorption and permeability of orally administered drugs by in-situ perfusion studies. • Use of HPLC as an analytical method in quantification and drug quality control. • Development of an HPLC method that simultaneously detects atenolol, metoprolol, and phenol red (zero permeability marker). Single-pass intestinal perfusion (SPIP) method is a widely used experimental model to determine the intestinal permeability of drugs. These studies are performed in the presence of a reference standard (metoprolol, MT) and a zero permeability marker (phenol red, PR). Therefore, it is important to develop a validated method for simultaneous determination of the investigated compound along with MT and PR. The aim of this study was to develop a reversed phase high-performance liquid chromatography (RP-HPLC) method with UV-detection for the simultaneous determination of atenolol (ATN), MT, and PR in the perfusion medium used in SPIP experiments. Separation of compounds were performed using an InertSustain C18 (250 × 4.6 mm, 5 µm) HPLC column at 35 °C. The mobile phase was a mixture of acetonitrile and phosphate buffer (pH 7.0, 12.5 mM) in gradient elution, and was delivered at a flow rate of 1 mL/min. The acetonitrile ratio of the mobile phase increased linearly from 10 to 35 % over 15 min. The injection volume was 20 µL, and ATN, MT and PR were detected at 224 nm. The retention times under optimum HPLC conditions were 5.028 min, 12.401 min, and 13.507 min for ATN, MT and PR, respectively. The developed RP-HPLC method was validated for selectivity, specificity, calibration curve and range, accuracy and precision, carry-over effect, stability, reinjection reproducibility, recovery and robustness. The method was linear for ATN (0.76–50 μg/mL), MT (1.14–50 μg/mL), and PR (0.47–20 μg/mL) with determination coefficients of 0.9999, 0.9994 and 0.9998, respectively. The results obtained for all validation parameters of the developed RP-HPLC method met the required limits of the ICH M10 Guideline. [ABSTRACT FROM AUTHOR]

BGT-002, a new type of ATP-citrate lyase inhibitor, is a promising therapeutic for treatment of hypercholesterolemia. After an oral administration of BGT-002 to subjects, it underwent extensive metabolism and an acyl monoglucuronide (ZM326E-M2) on 1- carboxylic acid group was the major circulating metabolite. In this study, an LC-MS/MS method was developed and validated for the simultaneous determination of BGT-002 and ZM326E-M2 in plasma and the evaluation of their pharmacokinetic characteristics in humans. After extraction from the plasma by acetonitrile-induced protein precipitation, the analytes were separated on a Waters ACQUITY UPLC® BEH C 18 column using acetonitrile and 2 mM ammonium acetate containing 0.1% formic acid as the mobile phase for gradient elution. Negative electrospray ionization was performed using multiple reaction monitoring (MRM) of m/z 501.3→325.4 for ZM326E-M2 and m/z 507.3→331.2 for D 6 -ZM326E-M2, and pseudo-MRM of m/z 325.3→325.3 for BGT-002 and m/z 331.3→331.3 for D 6 -ZM326E, respectively. The method was validated with respect to accuracy, precision, linearity, stability, selectivity, matrix effect, and recovery. The analytical range in human plasma was linear over a concentration range of 0.0500–50.0 μg/mL for BGT-002 and 0.0100–10.0 μg/mL for ZM326E-M2. The pharmacokinetic results showed that after a single oral administration of 100 mg BGT-002, the parent drug was rapidly absorbed with a mean time to peak concentration (t max) of 1.13 h, compared with BGT-002, the t max (4.00 h) of ZM326E-M2 was significantly delayed. The peak concentration and plasma exposure of ZM326E-M2 were about 14.1% and 19.5% of the parent drug, suggesting that attention should be paid to the safety and efficacy of ZM326E-M2 in clinical research. • BGT-002 is a new type of ATP-citrate lyase inhibitor developed for hypercholesterolemia therapy • First LC-MS/MS method for the simultaneous quantification of BGT-002 and its acyl glucuronide metabolite in human plasma. • The developed method was successfully applied to a clinical pharmacokinetic study. [ABSTRACT FROM AUTHOR]

• A sensitive method was developed for letrozole and its carbinol metabolite in mouse plasma. • Limited sample volumes allow implementation in large-scale pharmacokinetic studies. • Letrozole levels in plasma are formulation- and strain-dependent. A liquid chromatography - electrospray ionization-mass spectrometry (LC-ESI-MS) method was developed for the quantification of letrozole, a third-generation aromatase inhibitor, and its main carbinol metabolite (CM) in support of murine pharmacokinetic studies. Using polarity switching, simultaneous ESI-MS measurement of letrozole and CM was achieved in positive and negative mode, respectively. The assay procedure involved a one-step protein precipitation and extraction of all analytes from mouse plasma requiring only 5 μL of sample. Separation was optimized on an Accucore aQ column with gradient elution at a flow rate of 0.4 mL/min in 5 min. Two calibration curves per day over four consecutive measurement days showed satisfactory linear responses (r 2 > 0.99) over concentration ranges of 5–1000 ng/mL and 20–2000 ng/mL for letrozole and CM, respectively. No matrix effect was found, and the mean extraction recoveries were 103–108 % for letrozole and 99.8–107 % for CM. Precision and accuracy within a single run and over four consecutive measurement days were verified to be within acceptable limits. Application of the developed method to preclinical pharmacokinetic studies in mice receiving oral letrozole at a dose 1 or 10 mg/kg revealed that the systemic exposure to letrozole was dose-, formulation-, and strain-dependent. These findings may inform the future design of preclinical studies aimed at refining the pharmacological profile of this clinically important drug. [ABSTRACT FROM AUTHOR]

A liquid chromatography‐tandem mass spectrometry method was developed and validated for the simultaneous quantification of vincristine and tariquidar in 10 μL of mouse whole blood using volumetric absorptive microsampling devices. Samples were extracted from the devices and quantified against calibrators prepared in a human blood plasma matrix. Separation of vincristine and tariquidar was achieved using a Shimpack XR ODS III C18 stationary phase and H2O and methanol mobile phase solvents containing 0.1% formic acid, running a gradient elution at a flow rate of 0.2 mL/min over 6.0 min. The method was linear up to 1200 ng/mL (R2 > 0.99 for both analytes), with calibrator accuracy within ± 15% of the nominal concentrations and analyte coefficient of variance <15% for both vincristine and tariquidar. Pharmacokinetic assessment of both analytes was successfully applied in mice as both single‐agent therapy and combination therapy over a 24‐h period, and a 2.3‐fold increase in vincristine drug exposure was observed in combination with tariquidar. This study validates the use of this approach for longitudinal analysis of drug exposure in animal studies. [ABSTRACT FROM AUTHOR]

Thymus immunosuppressive pentapeptide (TIPP) is a novel anti-inflammatory peptide with high efficacy and low toxicity. This study aims to establish a selective LC-MS/MS method for analyzing the analyte TIPP in biological samples, laying the foundation for further PK and PD studies of TIPP. Protein precipitation was conducted in acetonitrile supplemented with 2% formic acid and 25 mg/mL dithiothreitol as a stabilizer, which was followed by backwashing the organic phase using dichloromethane. The chromatographic separation of TIPP was achieved on a C18 column with a gradient elution method. During positive electrospray ionization, TIPP was analyzed via multiple-reaction monitoring. The linear relationships between the concentration of TIPP and peak area in murine plasma cell lysates, supernatants, and the final cell rinse PBS were established within the ranges of 20–5000 ng/mL, 1–200 ng/mL, 10–200 μg/mL, and 0.1–20 ng/mL, respectively (r2 > 0.99). Validated according to U.S. FDA guidelines, the proposed method was proved to be acceptable. Such a method had been successfully applied to investigate the pharmacokinetics of TIPP in mice via subcutaneous injection. The plasma half-life in mice was 5.987 ± 1.824 min, suggesting that TIPP is swiftly eliminated in vivo. The amount of TIPP uptake by RBL-2H3 cells was determined using this method, which was also visually verified by confocal. Furthermore, the effective intracellular concentration of TIPP was deduced by comparing the intracellular concentration of TIPP and degrees of inflammation, enlightening further investigation on the intracellular target and mechanism of TIPP. [ABSTRACT FROM AUTHOR]

MPI8, a peptidyl aldehyde, is a potent antiviral agent against coronavirus. Due to unique tri-peptide bonds and the formyl functional group, the bioassay of MPI8 in plasma was challenged by a strong interference from water MPI8. Using QTOF LC-MS/MS, we identified MPI8•H2O as the major interference form that co-existed with MPI8 in aqueous and biological media. To avoid the resolution of MPI8 and MPI8•H2O observed on reverse phase columns, we found that a Kinetex hydrophilic interaction liquid chromatography (HILIC) column provided co-elution of both MPI8 and MPI8•H2O with a good single chromatographic peak and column retention of MPI8 which is suitable for quantification. Thus, a sensitive, specific, and reproducible LC-MS/MS method for the quantification of MPI8 in rat plasma was developed and validated using a triple QUAD LC-MS/MS. The chromatographic separation was achieved on a Kinetex HILIC column with a flow rate of 0.4 mL/min under gradient elution. The calibration curves were linear (r2 > 0.99) over MPI8 concentrations from 0.5–500 ng/mL. The accuracy and precision are within acceptable guidance levels. The mean matrix effect and recovery were 139% and 73%, respectively. No significant degradation of MPI8 occurred under the experimental conditions. The method was successfully applied to a pharmacokinetic study of MPI8 after administration of MPI8 sulfonate in rats. [ABSTRACT FROM AUTHOR]

Fangji Huangqi Decoction is composed of Stephaniae Tetrandrae Radix, Astragli Radix, Atractylodis Macrocephalae Rhizoma and Glycyrrhizae Radix Et Rhizoma. It is a classic traditional Chinese medicine formula for the treatment of chronic glomerulonephritis in China. However, its pharmacokinetic characteristics in vivo are still unclear. In this study, a method for quantifying fangchinoline, tetrandrine and calycosin-7-O-β-D-glucoside, the main active constituents of Fangji Huangqi Decoction, in rat plasma by using ultrahigh-performance liquid chromatography–tandem mass spectrometry technique was developed. Plasma samples were processed with a deproteinization procedure using acetonitrile, followed by chromatographic separation on a Shim-pack XR-ODS C18 column using gradient elution of 0.1% aqueous formic acid and acetonitrile at 0.4 mL/min. The analytes and internal standard, diphenhydramine hydrochloride, were detected using positive electrospray ionization in multiple reactions monitoring mode. The optimized mass transition ion-pairs (m / z) were 609.3/367.3 for fangchinoline, 623.3/174.3 for tetrandrine, 447.2/285.1 for calycosin-7-O-β-D-glucoside and 256.2/167.1 for diphenhydramine hydrochloride, respectively. The developed method was validated for intraday and interday precision and accuracy whose values fell in the acceptable limits. Recovery efficiency of all the analytes was found to be >90.5%. Matrix effect was found to be negligible. Stability results showed that the analytes were stable under all conditions. The validated method was successfully used for studying the pharmacokinetics of the three compounds in rat plasma after oral administration of Fangji Huangqi Decoction. [ABSTRACT FROM AUTHOR]

Cinnarizine is a weak base, which can produce supersaturation and precipitation during gastrointestinal transit, affecting its absorption in vivo. Therefore, it is necessary to investigate whether the oral bioavailability of cinnarizine can be improved after co‐administration with precipitation inhibitors or not. In order to evaluate the pharmacokinetic behavior of cinnarizine in rats, a simple, rapid, sensitive, and environmentally friendly supercritical fluid chromatography‐tandem mass spectrometric method was established and validated. In this method, flunarizine, a structural analogue of cinnarizine, was selected as the internal standard, and cinnarizine was extracted from rat plasma using evaporation‐free liquid–liquid extraction method. The analytes were separated on a Torus 1‐AA column (3.0 mm × 100 mm, 1.7 μm) within 2.0 min, using a gradient elution procedure. The transitions of cinnarizine and flunarizine were m/z 369.1 → 167.1 and m/z 405.1 → 203.1, respectively. Cinnarizine showed good linear correlation in the range of 1–500 ng/ml with a lower limit of quantification of 1 ng/ml. The intra‐ and interday precision and accuracy of all quality control samples were within ±15%. This high‐throughput, accurate, sensitive, and reproducible method has been successfully applied to study the effects of the precipitation inhibitor cinnarizine on the pharmacokinetics in rats. [ABSTRACT FROM AUTHOR]

Qilong capsule (QLC) is a well-known Traditional Chinese Medicine, and it has a long history for the treatment of ischemic stroke. Its major ingredients are saponins, such as paeoniflorin, amygdalin and calycosin-7-glucoside, contributing to vasodilation function. In this study, a simple, rapid and sensitive high-performance liquid chromatography-tandem mass spectrometry method was developed to determine three bioactive ingredients in rat plasma after oral administration of QLC. A simple acetonitrile precipitation method was introduced during the sample preparation. Chromatographic separation was performed on a Shiseido CAPCELL PAC MGIII-C18 column using a gradient elution with acetonitrile and water (0.1% formic acid) as a mobile phase, and the chromatographic separation was 5 min. The methodological evaluation showed that this method had a high sensitivity (the lower limit of quantification was 1 ng/mL for calycosin-7-glucoside, 5 ng/mL for paeoniflorin, 5 ng/mL for amygdalin), satisfactory accuracy (relative error ≤ ±15%) and precision (relative standard deviation ≤15%). Then, the analytical method was applied to the pharmacokinetic study in rats following oral administration of the extracts in QLC. Meanwhile, the pharmacokinetic parameters of complex system in QLC were analyzed and the potential interaction between ingredients was explored. The present quantification method and pharmacokinetic study will provide a meaningful reference for the formulas research of QLC in the treatment of ischemic stroke. Highlight A simple, rapid and sensitive HPLC–MS/MS analytical method was developed for the simultaneous determination of three ingredients in rat plasma after oral administration of QLC. A simple acetonitrile precipitation method was introduced to extract three biomedical ingredients during the plasma sample preparation. The pharmacokinetic results revealed the pharmacological active substances, identified internal variation rules and provided a meaningful reference for the formulas research of QLC in the treatment of ischemic stroke. [ABSTRACT FROM AUTHOR]

Unecritinib (TQ-B3101) is a selective tyrosine kinase receptor inhibitor. In the study, in vitro metabolic experiments revealed that the hydrolysis of TQ-B3101 was mainly catalyzed by carboxylesterase 2 (CES2), followed by CES1. Next, a sensitive and reliable LC-MS/MS method was established for the simultaneous determination of TQ-B3101 and its metabolite crizotinib in rat plasma. To prevent in vitro hydrolysis of TQ-B3101, sodium fluoride, the CESs inhibitor at a concentration of 2 M , was immediately added after whole blood collection. Plasma samples were extracted by acetonitrile-induced protein precipitation method, and chromatographically separated on a Gemini C 18 column (50 mm × 2.0 mm i.d., 5 μm) using gradient elution with a mobile phase of 0.1% formic acid and 5 mmol/L ammonium acetate with 0.1% formic acid. The retention times for TQ-B3101 and crizotinib were 2.61 and 2.38 min, respectively. The analytes were detected with tandem mass spectrometer by positive electrospray ionization, using the ion transitions at m/z 492.3 → 302.3 for TQ-B3101, m/z 450.3 → 260.3 for crizotinib, and m/z 494.0 → 394.3 for imatinib (internal standard). Method validation was conducted in the linear range of 1.00–800 ng/mL for the two analytes. The precision, accuracy and stabilities all met the acceptance criteria. The pharmacokinetic study indicated that TQ-B3101 was rapidly hydrolyzed to crizotinib with the elimination half-life of 1.11 h after a single gavage administration of 27 mg/kg to Sprague-Dawley rats, and the plasma exposure of TQ-B3101 was only 2.98% of that of crizotinib. • TQ-B3101 is an amide prodrug of crizotinib, a selective tyrosine kinase receptor inhibitor. • First LC-MS/MS method for the simultaneous quantification of TQ-B3101 and crizotinib in rat plasma. • The developed method was successfully applied to a pharmacokinetic study. [ABSTRACT FROM AUTHOR]

A sensitive, reproducible, robust, high-throughput ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous quantification of fexofenadine and olmesartan in human serum. Samples (50 µL) undergo protein precipitation prior to UPLC-MS/MS analysis. The analytes were separated using an Acquity BEH C18 column (2.1 mm × 50 mm, 1.7 µm) at a flow rate of 0.5 mL/min using a gradient elution with a total run time of 4 min. The analytes were detected in positive ion mode and selected reaction monitoring (SRM) was used for quantitation. The standard curve concentration range was 1.0–500.0 ng/mL for both analytes and each analyte showed excellent linearity with correlation coefficients (R2 > 0.99). The intra- and inter-day accuracy and precision were ±15% for each analyte, and excellent recovery was demonstrated (93–98%) for both analytes. The method is well suited for high-throughput quantitative determination of fexofenadine and olmesartan simultaneously and was successfully applied to an in vivo pharmacokinetic and transporter phenotyping study in humans. • An assay was validated for fexofenadine and olmesartan quantitation in human serum. • Excellent linearity was achieved for both drugs between 1.0 and 500.0 ng/mL. • A simplified sample preparation procedure allowed for high-throughput analysis. • The method was successfully applied to a pharmacokinetic study in humans. [ABSTRACT FROM AUTHOR]

Areca nuts have been used as a traditional Chinese medicine (TCM) for thousands of years. Recent studies have shown that it exhibits good pharmacological activity and toxicity. In this study, the pharmacokinetics of five major components of areca nut extract in rats were investigated using a highly sensitive ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-MS/MS) method. Arecoline, arecaidine, guvacoline, guvacine, and catechin were separated and quantified accurately using gradient elution with mobile phases of (A) water containing 0.1 % formic acid-10 mM ammonium formate, and (B) methanol. The constituents were detected under a timing switch between the positive and negative ion modes using multiple reaction monitoring (MRM). Each calibration curve had a high R2 value of >0.99. The method accuracies ranged −7.09–11.05 % and precision values were less than 14.36 %. The recovery, matrix effect, selectivity, stability, and carry-over of the method were in accordance with the relevant requirements. It was successfully applied for the investigation of the pharmacokinetics of these five constituents after oral administration of areca nut extract. Pharmacokinetic results indirectly indicated a metabolic relationship between the four areca nut alkaloids in rats. For further clarification of its pharmacodynamic basis, this study provided a theoretical reference. • Sensitive detection of five major components in areca nut using UPLC-MS/MS method. • The pharmacokinetics study of five major components of areca nut extract in rats. • The results indicated a metabolic relationship between the four alkaloids in rats. [ABSTRACT FROM AUTHOR]

DO-2 is a highly selective MNNG HOS transforming (MET) inhibitor. This deuterated drug is thought to diminish the formation of the Aldehyde Oxidase 1 inactive metabolite M3. For various reasons, quantification of DO-2 and its metabolites M3 and DO-5 is highly relevant. In this study, we present an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method to quantify DO-2, M3 and DO-5. Rolipram served as the internal standard. Aliquots of 25 µL were mixed with 100 µL internal standard consisting of 10 ng/mL rolipram in acetonitrile. Separation of the analytes was achieved on an Acquity UPLC ® HSS T3 column, utilizing gradient elution with water/formic acid and acetonitrile/formic acid at a flow-rate of 0.400 mL/min. Calibration curves were linear in the range of 1.00 – 1000 ng/mL for DO-2 and DO-5, and 2.00 – 2000 ng/mL for M3 in human plasma. The within-run and between-run precisions of DO-2, DO-5 and M3, also at the level of the LLQ, were within 12.1%, while the accuracy ranged from 89.5 to 108.7%. All values for accuracy, within-run and between-run precisions met the criteria set by the Food and Drug Administration. The method was effectively employed in the analysis of samples obtained from a clinical trial. [Display omitted] • We describe the first UPLC-MS/MS method for the analysis of DO-2 and its metabolites DO-5 and M3 in human plasma. • The assay met all of the current requirements of bioanalytical method validation. • Clinical applicability of the assay was demonstrated for pharmacokinetic analysis in clinical pharmacokinetic studies. [ABSTRACT FROM AUTHOR]

• Develop and validate an LC-MS/MS method for the quantification of six small molecule Anti-SARS-CoV-2 drugs in plasma. • The devised methodology was effectively utilized in a pharmacokinetic study following the oral administration of six small molecule Anti-SARS-CoV-2 drugs in rats. • Presents a significant tool for preclinical and clinical investigations of six small molecule Anti-SARS-CoV-2 drugs, generating interest in further research on anti-Covid19 drugs. Antiviral treatment for COVID-19 is considered an effective tool in reducing the rate of severe cases and deaths. As of June 2023, a total of six small molecule antiviral drugs have been conditionally approved for marketing by the National Medical Products Administration (NMPA) within China. In this study, a method of HPLC-MS/MS was established and validated for the determination of six small molecule antiviral drugs in plasma using Lamivudine as an internal standard. The chromatographic separation was performed using gradient elution with an ACE 3 C 18 -PFP column (3.0 mm × 150 mm, 3 μm), and the mobile phase consisted of deionized water and acetonitrile/water (90:10, v/v), both with 10 mmol/L of ammonium acetate and 0.1 % ammonium hydroxide added. Quantitative analysis of the six small molecule drugs was carried out through selective reaction monitoring based on the positive ion spray ionization mode. The method exhibited excellent precision, accuracy, recovery, and linearity, and it was used to determine the pharmacokinetic characteristics in rats. Our work not only established a bioanalytical method for six small molecule antiviral drugs but also provided scientific references for clinical pharmacokinetic studies. [ABSTRACT FROM AUTHOR]

• A LC-MS/MS method for simultaneous quantification of insulin and liraglutide. • Method was developed and validated following FDA and EMA guidelines. • The method was applied to pharmacokinetics and biodistribution of drugs in rats. • Drugs were quantified in plasma, brain, lung, spleen, liver and kidneys. We present an ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous detection of insulin degludec (I-Deg) and liraglutide (LIRA) in rat plasma and tissues, characterized by its sensitivity and selectivity. Chromatographic separation was achieved using an Acquity UPLC BEH C18 column, leveraging a mobile phase of acetonitrile and water (both with 0.1 % formic acid) under gradient elution over a run time of 7.5 min. The mass spectrometer operated in positive electrospray ionization multiple reaction monitoring (MRM) mode, tracking transitions of m / z 1221.6 → 641.6 for I-Deg, m / z 938.7 → 1064.1 for LIRA, and m / z 1184.7 → 454.4 for the internal standard. Validation ranged from 5 to 100 ng/mL, exhibiting robust linearity (r2 > 0.99) and limits of detection (LOD) of 1.63–2.02 ng/mL for I-Deg and 0.96–1.62 ng/mL for LIRA. Limits of quantification (LOQ) were 2.38–4.76 ng/mL for I-Deg and 3.22–4.40 ng/mL for LIRA. Notably, no significant matrix effects were detected. Stability was confirmed under various conditions, and precision metrics (intraday RSD 1.68–8.05 % for I-Deg and 1.11–7.69 % for LIRA; interday RSD 1.39–8.61 % for I-Deg and 1.06–8.83 % for LIRA) alongside accuracy (90.5–114.9 % for I-Deg and 92.7–113.7 % for LIRA) were within acceptable ranges. The method was successfully applied to pharmacokinetic and biodistribution studies following simultaneous subcutaneous administration of LIRA and I-Deg in rats. [ABSTRACT FROM AUTHOR]

The eburnamine-vincamine alkaloids exhibit a range of pharmacological activities. There is a limited understanding of the pharmacokinetics and pharmacodynamics of vindeburnol, a synthetic derivative of this chemical class of alkaloids. A fast and reliable UPLC-HRMS method was developed and validated to quantify vindeburnol in Soviet Chinchilla rabbit plasma from pharmacokinetics studies. An ultra-performance liquid chromatography system equipped with a Waters Acquity UPLC HSS T3 column was used for chromatographic separation by gradient elution with 0.1% (v/v) formic acid in water and acetonitrile. An Impact II QqTOF high-resolution mass spectrometer equipped with an Apollo II electrospray ionization source was used for analysis in positive mode; the ions [M+H]+ m/z 269.1648 ± 0.003 and m/ z 351.2067 ± 0.003 were monitored for vindeburnol and internal standard (vinpocetine), respectively. Preliminary metabolite profiling was also performed, and the pharmacokinetics of the identified metabolites were evaluated. The mean retention times for vindeburnol and vinpocetine were 2.0 and 3.5 min. The UPLC–HRMS method was validated with accuracy and precision within the 15% acceptance limit (8.2% and 11.0%, respectively). The mean extraction recovery value of vindeburnol from rabbit plasma was 77%. Pharmacokinetic evaluation of vindeburnol revealed that the compound is distributed rapidly with a short elimination half-life. Vindeburnol undergoes extensive first-pass metabolism and is metabolized into hydroxyvindeburnol and vindeburnol glucuronide. • A UPLC-HRMS method for the quantitative determination of vindeburnol was developed and validated. • The method was applied to study the pharmacokinetics of vindeburnol in rabbits. • A preliminary study of vindeburnol metabolism in rabbits was carried out. [ABSTRACT FROM AUTHOR]

Hydroxychloroquine (HCQ) was originally used as an antimalarial and immunomodulation drug. We developed and validated a simple and sensitive ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous quantitation of HCQ and its three metabolites in rat blood, and reported their pharmacokinetic parameters. The chromatographic separation and detection of analytes were achieved within 4 min on ZORBAX SB-C8 (3.5 μm, 2.1 × 150 mm) column with gradient elution, and the flow rate was 0.25 mL/min. Simple protein precipitation was successfully applied for sample pretreatment. The HCQ displays a good linearity in the range of 2.0–5000.0 ng/mL, and the three metabolites also show good linearity ranging from 1.0 to 2500.0 ng/mL, with all correlation coefficients (R2) better than 0.98. In conclusion, this rapid, sensitive method was successfully developed, validated, and then applied to a pharmacokinetic study of HCQ in rat model in high dose. The results of the pharmacokinetic study presented an average half-life time 21.14 ± 10.31 h (mean ± SD) of HCQ, which is much shorter in human compared to that in mice. For the three metabolites, longer half-life times (approximately 100 h) were shown in rat. [ABSTRACT FROM AUTHOR]

To investigate the pharmacokinetics of 2, 3, 8-trimethylellagic (TMEA) in rats in vivo and determine the possible effects of the pathological conditions and compatibility, a rapid and sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for quantitative determination was developed. TMEA and Artemetin (internal standard, IS) were separated on an Acquity Shim-pack GIST column with a total running time of 7 min using gradient elution at a flow rate of 0.3 mL/min. The intraday and interday relative standard deviations were <9.50%, and the relative error of accuracy was between −5.70% and 2.96%. The calibration curve of TMEA demonstrated good linearity with r2 = 0.9996, with the average recovery changing from 94.77% to 102.47% and the matrix effect from 93.16% to 100.15%. Compared with the normal group, the area under the plasma concentration-time curve from time 0 to the last time of quantifiable concentration (AUC(0 − t)), area under the plasma concentration-time curve from time 0 extrapolated to infinite time (AUC(0 − ∞)), and the maximum concentration (Cmax) of TMEA increased, whereas the time of maximum concentration (Tmax) and apparent clearance (CL/F) remarkably decreased in the TMEA group. With significantly reduced CL/F, AUC(0 − t), AUC(0 − ∞), and Cmax for TMEA were increased approximately one time after combining with 3, 7-Di-O-methylducheside A (DOMA). AUC(0 − t) and Cmax for TMEA in the 2, 3, 8-trimethylellagic-3, 8-dimethoxyellagic acid-2-oxyglucoside (TMEA-DMAG) group were significantly lower than that in the TMEA group with clearly prolonged Tmax and increased CL/F. These findings indicate that the changes in the pharmacokinetic parameters of TMEA may be caused by pathological and combination conditions. [ABSTRACT FROM AUTHOR]

Combination therapy is a common approach for clinical treatment of type 2 diabetes mellitus, especially for patients with poor monotherapy. Meta-analysis suggested that omarigliptin, a long-acting DPP-4 inhibitor, combined with pioglitazone might improve the side effects of pioglitazone. However, little is known about the pharmacokinetic properties after a coadministration. In this study, a rapid and reliable method for the simultaneous determination of the pioglitazone and omarigliptin in rat plasma by UHPLC-MS/MS was established and validated for the first time. An exsil mono C18 column (2.0 × 50 mm, 3 μm) was used to separate the analytes and the column temperature was kept at 30°C. Sitagliptin was selected as the internal standard. 0.02% formic acid aqueous solution (A) and methanol-acetonitrile (B) were used as mobile phases with gradient elution at a flow rate of 0.3 mL/min. The elution procedure was as follows: 20%B (0–0.1 min), 80%B (0.1–0.3 min), 80%B (0.3–2.0 min), and 20%B (2.1–3.0 min). A multiple reaction monitor (MRM) was used under positive ionization mode with electrospray ion source to detect pioglitazone (357.1 ⟶ 134.1), omarigliptin (399.2 ⟶ 153.0), and sitagliptin (408.2 ⟶ 235.0). The linear ranges of pioglitazone and omarigliptin were 5–2000 ng/mL and 10–4000 ng/mL, respectively. Good linear relationships were exhibited in the corresponding linear ranges (r ≥ 0.9944). The bioanalytical method was validated, and the selectivity, linearity, sensitivity, accuracy, precision, stability, recovery, and matrix effect were acceptable. The validated method was then successfully applied to pharmacokinetic study of pioglitazone combined with omarigliptin in rats. Results suggested that the combination of the two drugs had little effect on the pharmacokinetic parameters of each other in rats. [ABSTRACT FROM AUTHOR]

• A quantification method for KRAS-inhibitors Adagrasib and Sotorasib was developed. • This method may support pharmacokinetic research for Adagrasib and Sotorasib. • Revealing overexposure may help reduce treatment toxicity in clinical practice. • The method was co-validated with brigatinib, lorlatinib, pralsetinib & selpercatinib. Recently, two small molecular inhibitors (SMIs) –adagrasib and sotorasib– have been introduced for targeting Kirsten rat sarcoma (KRAS) p.G12C mutations in patients with non-small cell lung cancer (NSCLC). In order to support pharmacokinetic research as well as clinical decision making, we developed and validated a simple and accurate liquid chromatography-tandem mass spectrometry method for the multiplexed quantification of adagrasib and sotorasib. This assay was co-validated with the quantification for brigatinib, lorlatinib, pralsetinib and selpercatinib. Methanol was used for single-step protein precipitation. Chromatographic separation was performed using an Acquity® HSS C18 UPLC column, with an elution gradient of ammonium formate 0.1 % v/ v in water and acetonitrile. In K2-EDTA plasma, adagrasib was found to be stable for at least seven days at room temperature and 4 °C, and at least 3 months at −80 °C. Sotorasib was found to be stable for at least three days at room temperature, seven days at 4 °C and at least 3 months at −80 °C. The method was validated over a linear range of 80–4000 ng/mL for adagrasib and 25–2500 ng/mL for sotorasib. The assay is therefore well-equipped for determining plasma concentrations in clinical practice. [ABSTRACT FROM AUTHOR]

A sensitive and selective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method for the determination of apremilast in beagle dog plasma has been developed and successfully validated in the current study. Clopidogrel was employed as an internal standard (IS), and liquid-liquid extraction by tert-butylmethyl ether was used for sample preparation. Chromatographic separation was achieved on a UPLC BEH Shield RP18 column (50 mm × 2.1 mm, 1.7 μm) with 5 mM ammonium formate water and 5 mM ammonium formate methanol as the mobile phase with gradient elution. Calibration plots were linear in the range of 2–3000 ng/mL for apremilast in beagle dog plasma. Mean recoveries of apremilast in beagle dogs plasma ranged from 87.4% to 97.4%. The intrarun and interrun precision was less than 6% and 9%, respectively, with the accuracy between 92.4% and 101.1%. The method has also been successfully applied in the pharmacokinetics study of apremilast. The mean t1/2Z was 5.41 h for 30 mg·day−1 for beagle dogs after oral administration. The AUC0-t increased linearly from 3.51 to 1802.13 μ g L − 1 ∗ h after administration of single doses. [ABSTRACT FROM AUTHOR]

Osimertinib is a novel oral, potent, and irreversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) for treatment of advanced T790M mutation-positive advanced non-small cell lung cancer, which is commonly combined with ginsenoside Rg3 in clinic to enhance the efficacy and minimize adverse reactions. In the present study, a highly sensitive UPLC-MS/MS method was established and validated for analysis of osimertinib in rat plasma according to US FDA guideline. Separation was performed on a C18 (2.1 × 50 mm, 2.6 μm) column using a gradient elution of ammonium formate (10 mM) with 0.1% formic acid buffer (A) and ACN (B) at a flow rate of 0.2 mL/min. Detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization in the MRM mode. The method was validated over a concentration range of 1–400 ng/mL for osimertinib. The intra- and interday accuracy and precision values were within ±15%. No significant degradation occurred under the experimental conditions in stability assays. There was a further investigation on the effects of multiple doses of ginsenoside Rg3 on the pharmacokinetics of osimertinib in rats for the first time. The results implied that osimertinib exhibited a slow absorption and moderate-rate elimination in rats following oral administration. Coadministeration with ginsenoside Rg3 (5 mg/kg, 7 days, i.g.) may have no effect on the pharmacokinetics of osimertinib in rats. The results provide a reference for the clinical concomitant medications of Rg3 and osimertinib. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop a method for simultaneous analysis of aucubin, catalpol, and geniposide, which are representative iridoid glycoside constituents of Rehmannia glutinosa, in rat plasma, urine, and feces using hydrophilic interaction ultra high‐performance liquid chromatography with tandem mass spectrometry. The three components were separated using 10 mmol/L aqueous ammonium formate containing 0.01% (v/v) formic acid and acetonitrile as a mobile phase by gradient elution at a flow rate of 0.2 mL/min, equipped with a Kinetex® HILIC column (50 × 2.1 mm, 2.6 μm). Quantitation of this analysis was performed on a triple quadrupole mass spectrometer employing electrospray ionization and operated in multiple reaction monitoring mode. The chromatograms showed high resolution, sensitivity, and selectivity with no interference with plasma constituents. In all three iridoid glycosides, both the intra‐ and interbatch precisions (coefficient of variation %) were less than 4.81%. The accuracy was 96.56–103.55% for aucubin, 95.23–106.21% for catalpol, and 94.50–104.16% for geniposide. The developed analytical method satisfied the criteria of international guidance and was successfully applied to pharmacokinetic studies including oral bioavailability of aucubin, catalpol, and geniposide, and their urinary and fecal excretion ratios after oral or intravenous administration to rats. The new method was also applied to measure plasma protein binding ratios in vitro. [ABSTRACT FROM AUTHOR]

A selective, accurate, and efficient liquid chromatography‐tandem mass spectrometry method was developed for the simultaneous determination of 13 phenolic acids. Additionally, for more comprehensively determining the chemical constituents in Sanguisorba officinalis L. extract, a previously developed method was employed for the simultaneous determination of six triterpenes. Thus, two methods were used to ensure the comprehensiveness and reliability of this study. Based on these methods, the pharmacokinetic profiles of the 13 phenolic acids and 6 triterpenes in normal and leukopenia rats after oral administration of S. officinalis L. extract were compared for the first time in the present study. Quantitative detection of the 13 phenolic acids and 6 triterpenes was performed using the multiple reaction monitoring mode with the electrospray ion source in negative and positive electrospray ionization, respectively. Chromatographic separation was performed on an Agilent Eclipse Plus C18 RRHD column (50 × 2.1 mm, 1.8 µm) using gradient elution with a mobile phase composed of methanol–0.1% aqueous formic acid. The pharmacokinetic results demonstrated that the pharmacokinetic characteristics of the 19 analytes in leukopenia rats differed significantly from those determined in normal rats, which could provide a helpful reference for the clinical application of S. officinalis L. in the prevention and treatment of leucopenia. [ABSTRACT FROM AUTHOR]

Chimonanthi Radix (CR) is widely used in the treatment of influenza in China. Extensive studies revealed that the major bioactive constituents of CR were coumarins. However, pharmacokinetic study of coumarins in CR has not been fully studied. The purpose of this study was to establish a convenient and effective high-performance liquid chromatography–tandem mass spectrometry method that was used to simultaneously determine scopoletin, scopolin and isofraxidin in rat plasma after oral administration of CR extract using xanthotoxin as the internal standard. The chromatographic separation was carried out on a COSMOCORE C18 column (100 × 2 mm, 2.6 μm), using gradient elution with the mobile phase consisting of 0.1% formic acid (A) and acetonitrile (B). Three coumarins and IS were quantified by positive ion electrospray ionization in multiple reaction monitoring mode. The method was fully validated in terms of specificity, accuracy, precision (intra- and inter-day), matrix effect, recovery as well as the stability of the analytes under various conditions. The results could provide further research foundation for anti-influenza mechanism of three coumarins in CR. [ABSTRACT FROM AUTHOR]

Chaihu-shugan-san (CHSGS) has been widely used in China to treat depression and gastrointestinal diseases for thousands of years, but little is known about its pharmacokinetic properties. The purpose of our study is to develop a reliable and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method to detect five components in beagle plasma and study their pharmacokinetic after oral administration of CHSGS in beagles. An Agilent C18 column (2.1 × 150 mm, 3.5 μm) was used to separate the analytes, and the column temperature was maintained at 40°C. A gradient elution procedure was used with solvent A (acetonitrile) and solvent B (0.1% formic acid, aqueous) as mobile phases. The elution procedure was 60% B—10% B (0–3 min) and 10% B—60% B (3.1–4 min). The flow rate was 0.3 mL/min, and the total measurement time was 4 min. Within the determined range, the standard calibration curves of the five analytes had a satisfactory linear relationship (r2 ≥ 0.9923). The recovery rate (n = 6) of the five analytes was between 85.42% and 90.85%, and the matrix effects (n = 6) were between 94.52% and 103.91%. These results show that the validated method could be successfully applied to study the pharmacokinetic in beagles after a single dose of CHSGS. [ABSTRACT FROM AUTHOR]

Acute renal failure caused by Lianbizhi® injection can be attributed to andrographolide sodium bisulphite (ASB) and its main related substance RS413. For the safety evaluation of ASB and RS413, the pharmacokinetics of both compounds in rats was investigated through a liquid chromatography-tandem mass spectrometry method. After a simple protein precipitation with methanol, ASB and RS413 with dehydroandrographolide as an internal standard in plasma were separated on a C18 column using gradient elution with methanol and water and detected in the negative selected reaction monitoring mode. The intra- and inter-day accuracies of the method varied from 96 to 107% over the concentration range of 10–1000 ng/mL. Precisions were within 7.8% and the extraction recoveries ranged between 71–99% without obvious matrix effects. The method was applied for the simultaneous quantification of ASB and RS413 in rats treated intravenously with ASB and RS413 at the dose of 80 mg/kg for the first time. [ABSTRACT FROM AUTHOR]

Oroxylin A, obtained from the root of Scutellaria baicalensis Georgi, is a flavonoid with antitumor and other pharmacological activities. Our previous studies showed for the first time that it is mainly metabolized to oroxylin A sodium sulfonate by sulfotransferase enzymes in beagle dogs. In this study, rapid, universal, selective, and robust ultra‐high‐performance liquid chromatography–tandem mass spectrometry methods were established and fully validated to quantitatively detect oroxylin A, oroxylin A 7‐O‐glucuronide, and oroxylin A sodium sulfonate in beagle dog plasma. The quantitative analysis for oroxylin A sodium sulfonate was reported for the first time. Plasma samples were processed with acetonitrile, a universal protein precipitant. Gradient elution was performed to resolve carryover effects and to achieve separation efficiency and sufficient chromatographic retention. The linear relationships of oroxylin A, oroxylin A 7‐O‐glucuronide, and oroxylin A sodium sulfonate in plasma were in the range of 2.0–500.0, 5.0–500.0, and 1.881–940.5 ng/mL, respectively. The assay method was successfully applied to pharmacokinetic study. This is the first paper that reveals the pharmacokinetic profile of oroxylin A, oroxylin A 7‐O‐glucuronide, and oroxylin A sodium sulfonate after single‐dose intravenous and oral administration of Oroxylin A in beagle dogs. [ABSTRACT FROM AUTHOR]

Lusutrombopag is a second oral thrombopoietin (TPO) receptor agonist that selectively acts on human TPO receptors. In the study, UPLC-MS/MS was used to establish a selective and sensitive method to determine lusutrombopag with poziotinib as IS (internal standard) in rat plasma. Samples were prepared by precipitating protein with acetonitrile as a precipitant. Separation of lusutrombopag and poziotinib was performed on a CORTECS UPLC C18 column (2.1 ∗ 50 mm, 1.6 μm). The mobile phase (acetonitrile and water containing 0.1% formic acid) with gradient elution was set at a flow rate of 0.4 ml/min. The mass spectrometric measurement was conducted under positive ion mode using multiple reaction monitoring (MRM) of m/z 592.97 ⟶ 491.02 for lusutrombopag and m/z for poziotinib (IS) 492.06 ⟶ 354.55. The linear calibration curve of the concentration range was 2–2000 ng/ml for lusutrombopag, with a lower limit of quantification (LLOQ) of 2 ng/ml. RSD of interday and intraday precision were both no more than 9.66% with the accuracy ranging from 105.82% to 108.27%. The extraction recovery of lusutrombopag was between 82.15% and 90.34%. The developed and validated method was perfectly used in the pharmacokinetic study of lusutrombopag after oral administration in rats. [ABSTRACT FROM AUTHOR]

Radix Polygoni Multiflori (RPM) has been widely used to treat various diseases in Asian countries for many centuries. Although, stilbenes and anthraquinones, two major components of RPM, show various bioactive effects, it has been speculated that the idiosyncratic hepatotoxicity induced by RPM may be related to these constituents. However, information on the pharmacokinetics of stilbenes and anthraquinones at a subtoxic dose of RPM is limited. A simple and sensitive UPLC-MS/MS bioanalytical method for the simultaneous determination of 13 ingredients of RPM, including chrysophanol, emodin, aloe-emodin, rhein, physcion, questin, citreorosein, questinol, 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside, torachrysone-8-O-glucoside, chrysophanol-8-O-β-D-glucoside, emodin-8-O-β-D-glucoside, and physcion-8-O-β-D-glucoside, in rat plasma was established. Acetonitrile was employed to precipitate the plasma with appropriate sensitivity and acceptable matrix effects. Chromatographic separation was performed using a waters HSS C18 column with a gradient elution using water and acetonitrile both containing 0.025% formic acid within a run time of 9 min. The constituents were detected in negative ionization mode using multiple reaction monitoring. The method was fully validated in terms of selectivity, linearity, accuracy, precision, recovery, matrix effects, and stability. The lower limit of quantitation of the analytes was 0.1–1 ng/mL. The intrabatch and interbatch accuracies were 87.1–109%, and the precision was within the acceptable limits. The method was applied to a pharmacokinetic study after oral administration of RPM extract to rats at a subtoxic dose of 36 g/kg. [ABSTRACT FROM AUTHOR]

Icaritin (ICT) has distinct bioactivities, especially known for its beneficial effects on bone‐related degenerative disorders; however, its pharmacokinetic properties remain unknown. A novel developed UPLC‐MS/MS method for the determination of ICT and its main metabolite glucuronidated icaritin (GICT) was firstly applied to pharmacokinetic and metabolism studies of ICT in female rats, which were intraperitoneally given 40 mg/kg ICT. Following the protein precipitation of plasma samples with acetonitrile, ICT and GICT were separated on a C18 column using gradient elution mode and quantified in the multiple reaction monitoring mode. The linearities were acceptable for ICT (r = 0.9960) and GICT (r = 0.9968), and the lower limit of quantification values was 0.5 and 5 ng/ml, respectively. The accuracy fell in the range of 92.0%–103.1% and precisions were within 9.5%. Good linearity, accuracy, precision, and recovery were achieved for the UPLC‐MS/MS method. ICT was predominantly and rapidly biotransformed to GICT which was slowly eliminated in vivo with a terminal half‐life value of 4.51 hr. Pharmacokinetics of pure ICT eliminated biotransformation interference of Epimedium extract and disclosed genuine pharmacokinetic manner of ICT, as well as firstly elucidated low concentration and bioavailability of ICT in rat plasma. [ABSTRACT FROM AUTHOR]