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Arachidonic acid (AA) is a polyunsaturated fatty acid with a structure of 20:4(ω-6). Cytochrome P450s (CYPs) metabolize AA to several regioisomers and enantiomers of hydroxyeicosatetraenoic acids (HETEs). The hydroxy-metabolites (HETEs) exist as enantiomers in the biological system. The chiral assays developed for HETEs are so far limited to a few assays reported for midchain HETEs. The developed method is capable of quantitative analysis for midchain, subterminal HETE enantiomers, and terminal HETEs in microsomes. The peak area or height ratios were linear over concentrations ranging (0.01 -0.6 µg/ml) with r2 0.99. The intra-run percent error and coefficient of variation (CV) were ≤ ± 12 %. The inter-run percent error and coefficient of variation (CV)were ≤ ± 13 %, and ≤ 15 %, respectively. The matrix effect for the assay was also within the acceptable limit (≤ ± 15 %). The recovery of HETE metabolites ranged from 70 % to 115 %. The method showed a reliable and robust performance for chiral analysis of cytochrome P450-mediated HETE metabolites.

A selective and sensitive assay was developed for colchicine in rat specimens. Colchicine and its deuterated analog (as internal standard, IS) were extracted from rat specimens (minimal 0.1 mL plasma, whole blood, or urine) using liquid-liquid extraction with n-hexane:dichloromethane:isopropanol. The mobile phase (formic acid: ammonium acetate: methanol) was pumped with uniform flow through an octadecylsilane analytical column. Detection was carried out by electrospray positive ionization in the multiple-reaction monitoring mode. The assay (total run time &lt, 3 min) had excellent linearity over a wide (400–800-fold) concentration range. The mean absolute recovery was &gt, 96.8%. The intra- and inter-day coefficients of variation were ˂15%, with lower limits of quantitation of 0.5 ng/mL in 0.1 mL of rat plasma. The method also provided the same lower limits of quantitation in urine and whole blood with 0.1 mL volumes, and 0.1 ng/mL using 0.5 mL of rat plasma. The blood-to-plasma ratio was &gt, 1. Rats had measurable colchicine blood concentrations for at least 24 h after intravenous doses of 0.1 mg/kg. The method possessed suitable measures of sensitivity and selectivity for detecting colchicine in several specimen types in rats given low doses.

The development of a selective and sensitive high-performance liquid chromatographic tandem mass spectrometric method for the determination of cycloheximide (CHX) in rat blood and plasma is described. The extraction of CHX and colchicine as internal standard from blood fluid (0.1 mL) was achieved using n-hexane: dichloromethane: isopropanol (20:10:1 v/v/v). The mobile phase, a combination of methanol:10 mM ammonium acetate (85:15, v/v), was pumped at 0.2 mL/min through a C18 analytical column with a run time of 3.5 min. Detection was carried out by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring (MRM) mode. The assay exhibited excellent linearity (r

ObjectivesRectus sheath blocks are an established option for analgesia following abdominal surgery, but pharmacokinetic data are limited. This study sought to characterise the absorption of lidocaine injectate and the pharmacokinetics of lidocaine after rectus sheath injection.MethodsBilateral rectus sheath single-injection blocks were given to 10 patients undergoing general or urological surgery. Afterwards, serial lidocaine serum levels and ultrasound measurements of the rectus sheath injectate reservoir were collected.Key findingsInjectate within the rectus sheath was visible with ultrasound up to 12 h after injection. However, the rate of drug absorption exceeded that of injectate disappearance. Peak serum concentration occurred within 30 min with average peak concentrations of 1.65 μg/ml. Lidocaine clearance was lower than reported in young healthy subjects. The body mass index positively correlated with lidocaine terminal phase half-life, and clearance negatively correlated with age.ConclusionsThe study provides the first data describing lidocaine pharmacokinetics after rectus sheath injection. Peak serum concentrations transiently achieved systemic levels associated with pain relief after a single bolus injection. The data from this study could be used to develop a regime using single shot rectus sheath blockade with a bolus of lidocaine followed by infusion using bilateral rectus sheath catheters.

Introduction Admissions processes for entry-to-practice pharmacy programs across North America vary in the types of information used to decide which students to admit. The use of online interviews emerged at our program as an option to assess basic communication skills and personal traits to supplement traditional achievement measures such as prerequisite course grade point average (GPA) and admissions letters. Methods Student cumulative grade, year-by-year grade, and some grades from selected classes were correlated with the interview score for three years of consecutive cohorts. Linear regression was used to explore relationships. A survey was completed by students to understand their views on the use of the online interview process. Results There was no relationship seen between the compiled GPA and the interview score. The survey data revealed a strong preference for online compared to face-to-face interviews, with high student agreement that the interviews provide a good opportunity to demonstrate general communication skills. An assessment of the strength of the relationships of interview scores with a set of program GPA outcomes showed limited predictive utility. Scores weakly correlated with performance in communications and skills courses. Conclusions Online interviews were preferred over in-person interviews by most students. The lack of strong significant correlations between interview scores and grades suggests that use be judiciously applied in the overall admissions decision-making process.

Introduction In response to the COVID-19 pandemic, most universities in North America transitioned to online instruction and assessment in March 2020. Undergraduate pharmacy students in years one to three of two four-year entry-to-practice programs at a university in Canada were administered open-book examinations to complete their didactic winter-term courses in pharmaceutical sciences; behavioural, social, and administrative sciences; and pharmacotherapeutics. The impacts of the switch to open-book examinations on final exam characteristics are examined. Methods The ratios and correlations of final exam and midterm grades in 2020, where final exams were open-book, and in 2019, where finals were closed-book, were calculated and compared. Results In 2020, the ratio of final exam to midterm exam scores for five out of seven courses were significantly larger than they were in 2019. Alternatively, for all but one course, the correlations between midterm and final examination grades showed no significant difference from 2019 to 2020. Conclusions Compared to 2019 when finals were administered in a closed-book format, a sudden shift to an open-book format for final exams in 2020 appears to be associated with the final exams becoming easier relative to midterms. However, when considering how final and midterm exam grades correlate year over year, in all but one class, there was no significant difference. These findings suggest that changing exams to be open-book may change how they can be used to inform criterion-referenced or absolute grading decisions but not norm-referenced or rank-based decisions.

Purpose To investigate relationships between different prerequisite course grades and grade point average (GPA) of different types of academic performance in a Canadian entry-to-practice pharmacy program while controlling for important demographic variables. Methods Data from eight years of recently admitted students (2007–2014) were used to conduct a series of multiple linear regression analyses to assess relationships between prerequisite course GPA and eight different pharmacy school academic performance variables including: GPA in each of the first three years of the program, overall Y1-Y3 GPA, and GPA in pharmaceutical science, clinical science, clinical practice, and behavioral, social, and administrative (BSA) science courses. Demographic predictor variables including gender, mature status, and whether students attended ranked versus non-ranked universities were included as control variables. Results Analysis reveals that Biology and Biochemistry prerequisite GPA consistently predicts all eight academic performance variables while prerequisite English GPA was found to predict only clinical practice and BSA GPA. Being female and attending ranked universities were revealed as positively associated with most types of performance. Being classified as a mature student generally predicted lower academic performance. Conclusions The consistent relationship between biology-based prerequisites and academic performance warrants consideration for increasing their weight in admissions GPA calculations. The fact that the set of prerequisites and demographic variables are weaker predictors of clinical practice and BSA performance than pharmaceutical science performance provides empirical support for recent moves to include non-traditional admission criteria.

Purpose: Pharmacokinetic (PK) data are generally derived from blood samples withdrawn serially over a defined period after dosing. In small animals, blood sampling after dosing presents technical difficulties, particularly when short time intervals and frequent sampling are required. Positron emission tomography (PET) is a non-invasive functional imaging technique that can provide semi-quantitative temporal data for defined volume regions of interest (vROI), to support kinetic analyses in blood and other tissues. The application of preclinical small-animal PET to determine and compare PK parameters for [ 18 F]FDG and [ 18 F]FAZA, radiopharmaceuticals used clinically for assessing glucose metabolism and hypoxic fractions, respectively, in the same mammary EMT6 tumor-bearing mouse model, is reported here. Methods: Two study groups were used: normal BALB/c mice under isoflurane anesthesia were intravenously injected with either [ 18 F]FDG or [ 18 F]FAZA. For the first group, blood-sampling by tail artery puncture was used to collect blood samples which were then analyzed with Radio-microTLC. Dynamic PET experiments were performed with the second group of mice and analyzed for blood input function and tumor uptake utilizing a modified two compartment kinetic model. Heart and inferior vena cava vROIs were sampled to obtain image-derived data. PK parameters were calculated from blood samples and image-derived data. Time-activity curves (TACs) were also generated over regions of liver, kidney and urinary bladder to depict clearance profiles for each radiotracer. Results: PK values generated by classical blood sampling and PET image-derived analysis were comparable to each other for both radiotracers. Heart vROI data were suitable for analysis of [ 18 F]FAZA kinetics, but metabolic uptake of radioactivity mandated the use of inferior vena cava vROIs for [ 18 F]FDG analysis. While clearance (CL) and blood half-life (t½) were similar for both [ 18 F]FDG and [ 18 F]FAZA for both sampling methods, volume of distribution yielded larger differences, indicative of limitations such as partial volume effects within quantitative image-derived data. [ 18 F]FDG underwent faster blood clearance and had a shorter blood half-life than [ 18 F]FAZA. Kinetic analysis of tumor uptake from PET image data showed higher uptake and longer tumor tissue retention of [ 18 F]FDG, indicative of the tumor’s glucose metabolism rate, versus lower tumor uptake and retention of [ 18 F]FAZA. While [ 18 F]FAZA possesses a somewhat greater hepatobiliary clearance , [ 18 F]FDG clears faster through the renal system which results in faster radioactivity accumulation in the urinary bladder. Conclusions: The present study provides a working example of the applicability of functional PET imaging as a suitable tool to determine PK parameters in small animals. The comparative analysis in the current study demonstrates that it is feasible to use [ 18 F]FDG PET and [ 18 F]FAZA PET in the same model to analyze their blood PK parameters, and to estimate kinetic parameters for these tracers in tumor. This non-invasive imaging-based determination of tissue kinetic parameters facilitates translation from pre-clinical to clinical phases of drug development. This article is open to POST-PUBLICATION REVIEW . Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Obesity is caused by a number of factors including heredity, lack of exercise, and poor diet. Diets rich in fats and carbohydrates are the common culprits leading to obesity. Here we studied the effects of these components on proteins involved in drug disposition. Male rats were given a normal diet (lean controls) or one rich in fats, carbohydrates (as high-fructose corn syrup equivalent) or in combination. After 14 weeks, plasma biochemistry, liver and kidney mRNA and protein for selected cytochrome P450 (CYP) and transporters were determined. Significant increases in body and perinephric fat weight were noted in each of the high-calorie diet–fed groups, with increases being higher in those given high-fat diets. Increases in the protein of CYP3A1/2 and CYP2C11 were seen in liver in high-fat–fed rats. No changes were seen for CYP1A1 at the level of mRNA or protein. For transporters, decreases in expressions of Oct1/2 and Mate1 were seen, with no change in Mdr1. The results showed similarity to earlier assessments of genetically prone rats and suggested that diet-induced obesity has the potential to lead to decreases in the clearance of drugs acting as substrates for CYP 3A, 2C11, and organic cation transport.

Dronedarone biodistribution in hyperlipidemia and dronedarone metabolism in hyperlipidemia or obesity were assessed. Male Sprague–Dawley rats were given either normal standard chow with water or various high-fat or high-carbohydrate diets for 14 weeks. There was also a nonobese hyperlipidemic group given poloxamer 407 intraperitoneally. Liver and intestinal microsomes were prepared and the metabolic conversion of dronedarone to desbutyldronedarone was followed. A biodistribution study of dronedarone given orally was conducted in hyperlipidemic and control normolipidemic rats. The metabolism of dronedarone to desbutyldronedarone in control rats was consistent with substrate inhibition. However in the treatment groups, the formation of desbutyldronedarone did not follow substrate inhibition; hyperlipidemia and high-calorie diets created remarkable changes in dronedarone metabolic profiles and reduction in formation velocities. Tissue concentrations of dronedarone were much higher than in plasma. Furthermore, in hyperlipidemia, plasma and lung dronedarone concentrations were significantly higher compared to normolipidemia.

The effects of a high-fat diet on mRNA and protein of cytochrome P450 (CYP) enzymes in rats and mice and its impact on lidocaine deethylation to its main active metabolite, monoethylglycinexylidide (MEGX), in rats were investigated. The effect of a change in diet from high-fat to standard diet was also evaluated. Plasma biochemistry, mRNA, protein expression for selected CYP, and the activity of lidocaine deethylation were determined. The high-fat diet curtailed the activity and the expression of the majority of CYPs (CYP1A2, CYP3A1, CYP2C11, CYP2C12, and CYP2D1), mRNA levels (Cyp1a2 and Cyp3a2), and MEGX maximal formation rate (Vmax). Mice showed complementary results in their protein expressions of cyp3a and 1a2. Switching the diet back to standard chow in rats for 4 weeks reverted the expression levels of mRNA and protein back to normal levels as well as the maximum formation rates of MEGX. Female and male rodents showed similar patterns in CYP expression and lidocaine metabolism in response to the diets, although MEGX formation was faster in male rats. In conclusion, diet-induced obesity caused general decreases in CYP isoforms not only in rats but also in mice. The effects were shown to be reversible in rats by normalizing the diet.

The objectives of the current study were to characterize the pharmacokinetic profile of dronedarone in the rat, and to examine the effect of hyperlipidemia on its pharmacokinetics. Single doses of dronedarone were administered to rats intravenously (4 mg/kg), orally (55 mg/kg) and intraperitoneally (65 mg/kg). To induce hyperlipidemia, some of the rats were administered intraperitoneal doses of poloxamer 407 before giving an oral dose of dronedarone. After intravenous doses of 4 mg/kg dronedarone, plasma clearance and volume of distribution at steady-state were 25.1 ± 8.09 mL/min/kg and 10.8 ± 4.77 L/kg, respectively. After oral doses the maximum plasma concentrations (Cmax) and their median time of attainment (tmax) were 1.87 ± 1.65 mg/mL and 3.5 h, respectively. Intraperitoneal administration of 65 mg/kg dronedarone base yielded plasma Cmax and median tmax of 0.816 ± 0.611 mg/mL and 3 h, respectively. Protein binding was high in NL and HL plasma. Dronedarone is extensively distributed with high volume of distribution in the rat. The drug showed poor bioavailability (

Ketoconazole (KTZ) has 2 chiral centers with the therapeutically active form being a racemic mixture of 2 cis-enantiomers, namely, (2R,4S)-(+)-KTZ and (2S,4R)-(-)-KTZ. The aims of the present study were to examine the effects of (+)-KTZ, (-)-KTZ, and (±)-KTZ on aryl hydrocarbon receptor activation and subsequently CYP1A1 induction in both human HepG2 and murine Hepa1c1c7 hepatoma cells, and to further test their inhibitory effect using recombinant human and mouse CYP1A1 enzymes. Our results demonstrated that (+)-KTZ induced human CYP1A1 more than (-)-KTZ, whereas on the other hand (-)-KTZ induced murine Cyp1a1 more than (+)-KTZ at the mRNA, and activity levels. Human CYP1A1 showed higher affinity to 7ER compared with murine Cyp1a1 (Km values 13.29 nM for human vs. 168.1 nM for murine). The intrinsic clearance values for human and murine CYP1A1 were 194.1 and 87.6 μL/pmol P450/min, respectively, whereas, Vmax values were 2.58 and 14.73 pmol/pmol P450/min, respectively. (+)-KTZ and (-)-KTZ directly inhibited CYP1A1 activity by noncompetitive mechanism. The affinity of (-)-KTZ to interact with human CYP1A1 and murine Cyp1a1 was significantly different from (+)-KTZ, as the Ki values for human CYP1A1 and murine Cyp1a1 were 199.4 and 413.7 nM, respectively, for (+)-KTZ, and 269.3 and 230.8 nM, respectively, for (-)-KTZ.

The metabolism and biodistribution of the antiarrhythmic drug amiodarone (AM) was assessed in male Sprague-Dawley rats given either normal chow or high-fat and high-fructose diets for 14 weeks. After the feeding period, microsomes were prepared from liver and intestine, and the metabolism of AM to desethylamiodarone was determined. Intrinsic clearance (CL) was reduced by hepatic microsomes isolated from rats given high-calorie diets. In intestinal microsomes, there was no change or a small increase in metabolic rate in obese rats. A biodistribution study was also undertaken in a group of control and high-fat + high fructose-fed rats. Excess calories led to a significant increase in plasma AM compared to normal chow-fed control animals. A population pharmacokinetic analysis of AM confirmed that its oral CL was reduced. In plasma, there was a decrease in the metabolite to drug ratio. Some tissue:plasma ratios of AM in high calorie-fed rats were aligned with a decrease in plasma unbound fraction. It is concluded that the findings reinforced those of a recent report where we found decreases in expressions of enzymes involved in AM dealkylation, in showing greater exposure and lower oral CL, and generally decreases in liver microsomal metabolism of AM after high-calorie diets.

Receptor-interacting protein kinase 2 (RIP2 or RICK, herein referred to as RIPK2) is linked to the pathogen pathway that activates nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) and autophagic activation. Using molecular modeling (docking) and chemoinformatics analyses, we used the RIPK2/ponatinib crystal structure and searched in chemical databases for small molecules exerting binding interactions similar to those exerted by ponatinib. The identified RIPK2 inhibitors potently inhibited the proliferation of cancer cells by > 70% and also inhibited NFκB activity. More importantly, in vivo inhibition of intestinal and lung inflammation rodent models suggests effectiveness to resolve inflammation with low toxicity to the animals. Thus, our identified RIPK2 inhibitor may offer possible therapeutic control of inflammation in diseases such as inflammatory bowel disease, asthma, cystic fibrosis, primary sclerosing cholangitis, and pancreatitis.

A pharmacokinetics simulation teaching program is described.It is written in VBA in Excel for Windows.The program covers a wide variety of basic pharmacokinetic content.Students have responded favorably to its use. Pharmacokinetics can be a challenging topic to teach due to the complex relationships inherent between physiological parameters, mathematical descriptors and equations, and their combined impact on shaping the blood fluid concentration vs. time curves of drugs. A computer program was developed within Microsoft Excel for Windows, designed to assist in the instruction of basic pharmacokinetics within an entry-to-practice pharmacy class environment. The program is composed of a series of spreadsheets (modules) linked by Visual Basic for Applications, intended to illustrate the relationships between pharmacokinetic and in some cases physiological parameters, doses and dose rates and the drug blood fluid concentration vs. time curves. Each module is accompanied by a simulation user's guide, prompting the user to change specific independent parameters and then observe the impact of the change(s) on the drug concentration vs. time curve and on other dependent parameters. "Slider" (or "scroll") bars can be selected to readily see the effects of repeated changes on the dependencies. Topics covered include one compartment single dose administration (iv bolus, oral, short infusion), intravenous infusion, repeated doses, renal and hepatic clearance, nonlinear elimination, two compartment model, plasma protein binding and the relationship between pharmacokinetics and drug effect. The program has been used in various forms in the classroom over a number of years, with positive ratings generally being received from students for its use in the classroom.

Metformin pharmacokinetics are highly dependent upon organic cationic transporters. There is evidence of a change in its renal clearance in hyperlipidemic obese patients, and no information on its metabolic fate. To study some of these aspects, the influence of poloxamer 407 (P407)-induced hyperlipidemia on metformin pharmacokinetics was assessed. Control and P407-treated adult male rats were administered 30 mg/kg metformin intravenously (i.v.). The pharmacokinetic assessments were performed at 2 time points, 36 and 108 h, following the intraperitoneal dose of P407 (1 g/kg). mRNA and protein expressions of cationic drug transporters were also measured. There was no evidence of a change in metformin pharmacokinetics after i.v. doses as a consequence of short-term hyperlipidemia, and a change in transporter mRNA but not protein expression was observed in the P407- treated rats 108 h after P407 injection. Urinary recovery of unchanged drug was high (>90%) but incomplete. Presumed metabolite peaks were detected in chromatograms of hepatocytes and microsomal protein spiked with metformin. Comparative chromatographic elution times and mass spectra suggested that one of the predominant metabolites was guanylurea. Hyperlipidemia by itself did not affect the pharmacokinetics of metformin. Guanylurea is a putative metabolite of metformin in rats.

Two cases of mothers given postpartum short-term administration of amiodarone, with and without bisoprolol, are described along with determinations of amiodarone and (±)-bisoprolol in the breast milk. In one mother given a cumulative total of amiodarone of 8 g over 1 week, concentrations 11 days after the drug had been stopped were initially deemed sufficient to pose a risk to an infant. Over the next 5 days the concentrations steadily dropped with amiodarone and desethylamiodarone concentrations being found to be at a level comprising minimal risk to the infant. Bisoprolol was not found in the expressed breast milk. In the second case the mother was given a single 150 mg dose of amiodarone and breast milk concentrations were measured on postpartum days 4 and 5. Breast milk amiodarone concentrations were very low and of little concern clinically had the mother breast fed her baby. The risk to the baby of ingesting breast milk after amiodarone administration postpartum depends on the duration of amiodarone exposure, with a single dose posing minimal risk. Bisoprolol does not appear to accumulate to any great extent in breast milk.

A sensitive and selective high-performance liquid chromatographic method for the determination of dronedarone in rat plasma was developed. Dronedarone was extracted using one-step liquid-liquid extraction. The separation of dronedarone was accomplished using a C18 analytical column. The mobile phase was composed of a combination of monobasic potassium phosphate and acetonitrile. The UV detection was at 254 nm for ethopropazine, the internal standard, and after its elution, changed to 290 nm for dronedarone detection. The total analytical run time was 20 min. Mean recovery was >80%; the assay had excellent linear relationships (>0.999) between peak height ratios and plasma concentrations; the lower limit of quantification 25 was ng/mL, based on 100 μL of rat plasma. Accuracy and precision were

Dr. Fakhreddin Jamali: Pharmacist, Pharmaceutical Scientist and Mentor- Dedicated to An Academic Life and Legacy of Fame and Fortune

Experimental hyperlipidemia has shown to decrease cytochrome P450 3A4 and 2C11expression and toincreaseliver concentrationsand the plasmaprotein bindingofhalofantrine (HF) enantiomers. The present study examined the effect of hyperlipidemic (HL) serum on the metabolism of HF enantiomers by primary rat hepatocytes. Hepatocytes from normolipidemic (NL) and HL (poloxamer 407 treated) rats were incubated withrac-HF in cell media with or without additional rat serum (5%). In those incubations with rat serum, the hepatocytes were preincubated or coincubated with serum from NL or HL rats. Rat serum-free hepatocyte incubations served as controls. Stereospecific assays were used to measure HF and desbutylhalofantrine (its major metabolite) enantiomer concentrations in whole well contents (cells+media). Concentrations of desbutylhalofantrine were not measurable. The disappearance (apparent metabolism) of ()-HF exceeded that of antipode, but HF metabolism did not differ between hepatocytes from NL and HL rats. Coincubation of HL rat serum with NL hepatocytes caused a significant decrease in the disappearance of ()-HF, whereas in HL hepatocytes, a substantially decreased apparent metabolism was noted for both enantiomers. Compared with NL serum, ()-HF disappearance was significantly lowered upon preincubation of NL hepatocytes with HL serum. A combination of factors including diminished drug metabolizing or lipoprotein receptor expression, and increased plasma protein binding in the wells, may have contributed to a decrease in apparent metabolism of the HF enantiomers in the presence of lipoproteins from HL rat serum. Chirality 24:558-565, 2012. ©2 012 Wiley Periodicals, Inc.

Co-administration of P-glycoprotein (P-gp) inhibitors such as cyclosporine A (CyA) and its analogue valspodar with doxorubicin (DOX) can result in diminished clearance of DOX, leading to accentuated toxicity. The purpose of this study was to evaluate whether the effect of these P-gp inhibitors on the pharmacokinetics of DOX can be avoided through their encapsulation in polymeric micelles. Cyclosporine A or valspodar was physically encapsulated in methoxypoly(ethylene oxide)-b-poly(ε-caprolactone) (PEO-b-PCL) micelles using co-solvent evaporation method. The commercially available DOX was administered as a single dose of 5mg/kg intravenously to Sprague-Dawley rats either alone or 30min following a single intravenous dose (10mg/kg) of either CyA or valspodar as part of conventional or polymeric micellar formulation. Co-administration of DOX with either Sandimmune® or valspodar in the conventional Cremophor EL-based formulation was associated with greater than 50% reduction in DOX clearance (CL). Although there was nearly 40% reduction in the CL of DOX with the polymeric micellar formulation of CyA, there was only 6% reduction in CL of DOX upon co-administration with the polymeric micellar formulation of valspodar. In conclusion, encapsulation of cyclosporines, particularly valspodar, in polymeric micelles was shown to reduce their effects on the pharmacokinetics of DOX in rat.

The aim of this study was to characterize the nanostructures formed from assembly of poly(ethylene oxide)-bpoly( α-benzyl carboxylate e-caprolactone) (PEO-b-PBCL) in water, determine the effect of weight fraction of the hydrophilic block( fEO) on their morphology, and to investigate their potential for solubilization and delivery of P-glycoprotein (P-gp) inhibitor, valspodar. Three PEO-b-PBCL block copolymers having fEO ranging from 0.18-0.40 were synthesized. Assembly of PEO-b-PBCL was triggered through a co-solvent evaporation method. The average critical aggregation concentration (CAC) for PEO114-b-PBCL30, PEO114-b-PBCL60, and PEO114-b-PBCL95 was found to be 62, 41, and 23 nM, respectively. A lower rigidity of the hydrophobic domain in nanostructures formed from the assembly of PEO114-b- PBCL60 and PEO114-b-PBCL95 in comparison to PEO114-b-PBCL30 was observed. The morphology of the assembled structures was characterized by transmission electron microscopy (TEM). The TEM images of PEO114-b-PBCL30 (fEO = 0.40) showed the formation of spherical micelles with high polydispersity, whereas the assembly of PEO114-b-PBCL60 (fEO = 0.25) and PEO114-b-PBCL95 (fEO = 0.18) resulted in a mixed population of spherical micelles and vesicles. Valspodar achieved high loading in all the three PEO-b-PBCL nanocarriers reaching aqueous solubility of nearly 2 mg/mL. The morphology of PEO-b-PBCL carrier did not seem to influence the pharmacokinetics of the encapsulated valspodar in rats following intravenous administration. In conclusion, the results show a potential for PEO-b-PBCL nanocarriers as efficient solubilizing agents for delivery of valspodar.

As part of everyday life, people are exposed to polycyclic aromatic hydrocarbons (PAHs). Sources of PAHs include cigarette smoke, ingestion of contaminated food and water or specifically charcoal-grilled meat, and occupational exposure (e.g., the coal industry). PAH compounds are well known to have enzyme-inducing effects, especially on the cytochrome P450 (CYP) family of enzymes, including CYP1A. Enhanced clearance of CYP1A-metabolized drugs as a result of PAH exposure is well established. However, there are examples where PAH-containing sources enhanced the clearance or altered the disposition of some non-CYP1A-metabolized drugs. It has been shown that not only do these compounds induce CYP1A isoforms, but they also can alter the expression of other CYPs, such as 1B1/2 and 2E1, certain phase II enzymes, some transport proteins (in animal models and cell lines), levels of plasma proteins (e.g., α1-acid glycoprotein and lipoproteins), and liver mass. Changes in any of these parameters can lead to changes in the biological disposition of a wide variety of drugs by altering either their concentrations in blood or tissues. Identification of patients with elevated enzyme activities or otherwise altered physiological parameters as a consequence of exposure to PAH could serve to lessen the risks and optimize therapeutic benefits of drug therapy. In this article, the pharmacokinetic properties of PAH, the possible mechanisms by which they can alter drug disposition, and specific examples are discussed.

OBJECTIVE To determine the effect of metformin on the acute metabolic response to submaximal exercise, the effect of exercise on plasma metformin concentrations, and the interaction between metformin and exercise on the subsequent response to a standardized meal. RESEARCH DESIGN AND METHODS Ten participants with type 2 diabetes were recruited for this randomized crossover study. Metformin or placebo was given for 28 days, followed by the alternate condition for 28 days. On the last 2 days of each condition, participants were assessed during a nonexercise and a subsequent exercise day. Exercise took place in the morning and involved a total of 35 min performed at three different submaximal intensities. RESULTS Metformin increased heart rate and plasma lactate during exercise (both P ≤ 0.01) but lowered respiratory exchange ratio (P = 0.03) without affecting total energy expenditure, which suggests increased fat oxidation. Metformin plasma concentrations were greater at several, but not all, time points on the exercise day compared with the nonexercise day. The glycemic response to a standardized meal was reduced by metformin, but the reduction was attenuated when exercise was added (metformin × exercise interaction, P = 0.05). Glucagon levels were highest in the combined exercise and metformin condition. CONCLUSIONS This study reveals several ways by which metformin and exercise therapies can affect each other. By increasing heart rate, metformin could lead to the prescription of lower exercise workloads. Furthermore, under the tested conditions, exercise interfered with the glucose-lowering effect of metformin.

A liquid chromatographic mass spectrometric (LC-MS) assay for the quantification of nicotine and cotinine in human specimens was developed. Human serum and urine (100 μL) were subjected to liquid-liquid extraction. For glucuronidated cotinine, serum was alkalinized and hydrolyzed before extraction. The dried samples were reconstituted and run using gradient flow reverse-phase liquid chromatography with MS detection. The ions utilized for quantification of nicotine, cotinine and milrinone (internal standard) were 162.8, 176.9 and 211.9 m/z, respectively. The mean recoveries were over 80% for cotinine and nicotine with excellent linearity between nominal concentrations and peak area ratios, over a wide concentration range. The percentage coefficient of variation and mean error of the inter- and intra-day validations were

BACKGROUND AND PURPOSE Halofantrine can cause a prolongation of the cardiac QT interval, leading to serious ventricular arrhythmias. Hyperlipidaemia elevates plasma concentration of halofantrine and may influence its tissue uptake. The present study examined the effect of experimental hyperlipidaemia on QT interval prolongation induced by halofantrine in rats. EXPERIMENTAL APPROACH Normolipidaemic and hyperlipidaemic rats (induced with poloxamer 407) were given 4 doses of halofantrine (i.v., 4–40 mg·kg−1·d−1) or vehicle every 12 h. Under brief anaesthesia, ECGs were recorded before administration of the vehicle or drug and 12 h after the first and last doses. Blood samples were taken at the same time after the first and last dose of halofantrine. Hearts were also collected 12 h after the last dose. Plasma and heart samples were assayed for drug and desbutylhalofantrine using a stereospecific method. KEY RESULTS In the vehicle group, hyperlipidaemia by itself did not affect the ECG. Compared to baseline, QT intervals were significantly higher in both normolipidaemic and hyperlipidaemic rats after halofantrine. In hyperlipidaemic rats, plasma but not heart concentrations of the halofantrine enantiomers were significantly higher compared to those in normolipidaemic rats. Despite the lack of difference in the concentrations of halofantrine in heart, QT intervals were significantly higher in hyperlipidaemic compared to those in normolipidaemic rats. CONCLUSIONS AND IMPLICATIONS The unbound fraction of halofantrine appeared to be the controlling factor for drug uptake by the heart. Our data suggested a greater vulnerability to halofantrine-induced QT interval prolongation in the hyperlipidaemic state.

The aim of this study was to assess the potential of polymeric micelles to solubilize valspodar and modify its pharmacokinetics following intravenous and oral administration in rat. Drug-loaded methoxy poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) micellar solutions were prepared and administered either intravenously or orally to healthy Sprague-Dawley rats. Plasma pharmacokinetic parameters of valspodar in its polymeric micellar formulation were compared to its clinical formulation, which uses Cremophor EL and ethanol as solubilizing agents. High loading level was achieved for valspodar in PEO-b-PCL leading to an aqueous solubility of 2.8 mg/mL. Following i.v. administration (5 mg/kg), valspodar in the PEO-b-PCL micelles provided significantly higher (approximately 77%) plasma AUC compared to the Cremophor EL formulation. The PEO-b-PCL micelles also significantly decreased the volume of distribution (Vd(ss)) and clearance (CL) of valspodar by nearly 49% and 34%, respectively. After oral administration (10 mg/kg), the average C(max) were similar for both formulations and were both reached at approximately 2 h. The plasma unbound fraction of valspodar in the polymeric micellar formulation was significantly lower than control (8.27% versus 14.85%). Our results show that PEO-b-PCL micelles can efficiently solubilize valspodar and favorably modify its pharmacokinetic profile in rat after i.v. administration by decreasing the CL and Vd.

In the treatment of cardiac arrhythmias, amiodarone (AM) has emerged as a primary therapeutic agent. In addition to other cytochrome P450 (CYP), 1A1 and 1A2 facilitate the biotransformation of AM to the pharmacologically and toxicologically active metabolite, desethylamiodarone (DEA). The exposure to polycyclic aromatic hydrocarbons can induce these isoforms. This study was aimed at investigating the effect of CYP1A induction on the disposition of AM, after single and multiple intravenous doses, using β-naphthoflavone (BNF) treated rats to model induction of CYP1A. After a single dose (25 mg/kg), the plasma AUC of DEA were significantly induced (∼3-fold). With multiple doses, AM AUC0–24 h was significantly reduced in the BNF plasma (30%), lung (35%), liver (48%), kidney (52%), heart (34%), and intestine (43%). In contrast the DEA AUC0–24 h was increased significantly in the BNF plasma (36%), lung (56%), liver (101%), kidney (65%), and heart (73%). The DEA/AM ratios of the AUC0–24 h were increased in the BNF plasma, lung, liver, kidney, and heart by 1.9-, 2.5-, 3.8-, 3.4-, and 2.7-fold, respectively. In both groups of rats, the highest concentrations of AM and DEA were in the lung. Exposure to BNF was shown to increase DEA concentrations in the rat. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:539–548, 2010

Valspodar is a P-glycoprotein inhibitor widely used in preclinical and clinical studies for overcoming multidrug resistance. Despite this, the pharmacokinetics of valspodar in rat, a commonly used animal model, have not been reported. Here, we report on the pharmacokinetics of valspodar in Sprague-Dawley rats following intravenous and oral administration of its Cremophor EL formulation, which has been used for humans in clinical trials. After intravenous doses, valspodar displayed properties of slow clearance and a large volume of distribution. Its plasma unbound fraction was around 15% in the Cremophor EL formulation used in the study. After 10 mg kg(-1) orally it was rapidly absorbed with an average maximal plasma concentration of 1.48 mg l(-1) within approximately 2 h. The mean bioavailability of valspodar was 42.8%. In rat, valspodar showed properties of low hepatic extraction and wide distribution, similar to that of its structural analogue cyclosporine A.

The oral bioavailability of many lipophilic drugs is known to increase when coadministered with fatty meals. Although such a phenomenon is typically ascribed to increased solubilization and absorption of drug, in some cases this increase in systemic exposure may be in part due to the influence of lipids on the presystemic metabolism of the affected drug. Oral lipids on their absorption may interfere with the drug metabolizing enzymes expressed in the small intestine and/or liver. Fatty acids incorporated in dietary triglyceride can modulate the expression and activity of drug metabolizing enzymes within the small intestine. Lipoproteins, which are the major carriers of lipids in the systemic circulation, can become associated with lipophilic drugs. Such a combination may influence the metabolism of lipophilic drugs through limiting their uptake into the cells thereby decreasing their metabolism. In a contrary manner, an increased uptake and metabolism of lipoprotein-bound drug may be facilitated by lipoprotein receptors mediated uptake. The components of lipoproteins may also modulate the expression or activity of hepatic and extrahepatic drug metabolizing enzymes.

The stereoselective pharmacokinetics of ketoconazole (KTZ) enantiomers were studied in rat after i.v. and oral administration of (+/-)-KTZ. Sprague-Dawley rats were administered racemic KTZ as 10 mg/kg i.v. or orally over the range 10-80 mg/kg as single doses. Serial blood samples were collected over a 24-h period via surgically placed jugular vein cannulae. Plasma was assayed for KTZ enantiomer concentrations using stereospecific HPLC. Enantiomeric plasma protein binding was determined using an erythrocyte partitioning method at racemic concentrations of 10 and 40 mg/L. Stereoselective metabolism was tested by incubating the racemate (0.5-250 microM) with rat liver microsomes. In all rats, (+)-KTZ plasma concentrations were higher (up to 2.5-fold) than (-)-KTZ. The clearance and volume of distribution of the (-) enantiomer were approximately twofold higher than antipode. Half-life did not differ between the enantiomers. After oral doses the t(max) was not stereoselective. For both enantiomers with higher doses the respective half-life were found to increase. The mean unbound fraction of the (-) enantiomer was found to be up to threefold higher than that of the (+) enantiomer. At higher concentrations nonlinearity in plasma protein binding was observed for both enantiomers. There was no evidence of stereoselective metabolism by liver microsomes. Stereoselectivity in KTZ pharmacokinetics is attributable to plasma protein binding, although other processes such as transport or intestinal metabolism may also contribute.

To assess the influence of hyperlipidemia (HL) on amiodarone (AM) effect in the heart, rats were pretreated with either 1 g/kg poloxamer 407 (to induce HL) or saline intraperitoneally. At approximately 36 hours afterward, rats were given AM HCl (25, 50, and 100 mg.kg.d) or saline intravenously through implanted venous cannulas for 5 days. Under anesthesia, electrocardiogram (ECG) was recorded using subcutaneous electrodes and blood samples were withdrawn at baseline and 12 hours after the first, middle, and last doses. At the end of the study, heart tissues were collected. Specimens were analyzed for AM and desethylamiodarone. HL by itself did not alter the ECG. Compared with baseline, the end of study prolongation of QTc and PR intervals were significantly (P < 0.05) higher in all AM-treated HL rats. AM plasma and heart concentrations in HL rats after the last dose were significantly (P < 0.05) higher than in normolipidemic rats. Similar to AM, in HL rats, plasma desethylamiodarone after the last dose was significantly higher than in normolipidemic rats. The cholesterol to triglyceride plasma ratio was linearly related to QT interval and plasma and heart AM concentrations. HL increased the ECG effects of AM by increasing heart concentrations.

To model the impact of intestinal components associated with a high fat meal on metabolism of amiodarone, rat everted intestinal sacs were evaluated for their ability to metabolize the drug to its active metabolite (desethylamiodarone) under a variety of conditions. The preparations were obtained from fasted rats or rats pretreated with 1% cholesterol in peanut oil. After isolation of the tissues, the intestinal segments were immersed in oxygenated Krebs Henseleit buffer containing varying concentrations of bile salts, cholesterol, lecithin and lipase with or without soybean oil emulsion as a source of triglycerides. Amiodarone uptake was similar between the five 10-cm segments isolated distally from the stomach. Desethylamiodarone was measurable in all segments. Based on the metabolite-to-drug concentration ratio within the tissues, there was little difference in metabolic efficiency between segments for any of the treatments. Between treatments, however, it appeared that the lowest level of metabolism was noted in rats pretreated with 1% cholesterol in peanut oil. This reduction in metabolic efficiency was not observed in gut sacs from the fasted rats to which soybean oil emulsion was directly added to the incubation media. Despite the apparent reduction in intestinal metabolism, there was no apparent change in the ratio of metabolite-to-drug area under the plasma concentration versus time ratios of fasted rats and those given 1% cholesterol in peanut oil, suggesting that the intestinal presystemic formation of desethylamiodarone is not substantial.

A liquid chromatography-mass spectrometry (LC/MS) assay method was developed for the quantification of PSC 833 in rat plasma, using amiodarone as internal standard (IS). Separation was achieved using a C(8) 3.5 microm (2.1 mm x 50 mm) column heated to 60 degrees C with a mobile phase consisting of acetonitrile-ammonium hydroxide 0.2% (90:10 v/v) pumped at a rate of 0.2 mL/min. Detection was accomplished by mass spectrometer using selected ion monitoring (SIM) in positive mode. An excellent linear relationship was present between peak height ratios and rat plasma concentrations of PSC 833 ranging from 10 to 5000 ng/mL (R(2)>0.99). Intra-day and inter-day coefficients of variation (CV%) were less than 15%, and mean error was less than 10% for the concentrations above the limit of quantification. The validated limit of quantification of the assay was 10 ng/mL based on 0.1 mL rat plasma. The method limit of detection, based on an average signal-to-noise (S/N) ratio of 3, was found to be 2.5 ng/mL. The assay was capable of measuring the plasma concentrations of PSC 833 in rats injected with a single dose of 5 mg/kg of the drug. PSC 833 and IS eluted within 4 min, free of interfering peaks. The method was found to be fast, sensitive, and specific for the quantification of PSC 833 in rat plasma.

The pharmacokinetics of desethylamiodarone (DEA), the active metabolite of amiodarone (AM), were studied in the rat after administration of AM or preformed metabolite. Rats received 10 mg/kg of either intravenous or oral AM HCl or DEA base. Blood samples were obtained via a surgically implanted jugular vein cannula. Plasma concentrations were measured by a validated LC/MS method. In all AM treated rats, AM plasma concentrations greatly exceeded those of the formed DEA. The fraction of AM converted to DEA after i.v. administration was 14%. Amiodarone had a significantly lower (∼50%) clearance than DEA, although the volume of distribution and terminal phase half-life did not differ significantly. The hepatic extraction ratio of DEA was 0.48, similar to that of AM (0.51). Oral AM demonstrated higher plasma AUC (5.6 fold) and higher Cmax (6.1 fold) than oral DEA and oral bioavailability of AM (46%) was greater than DEA (17%). The estimated fraction of the oral dose of AM converted to DEA was 4.5 fold higher than after i.v. administration, suggesting first-pass formation of DEA from AM. Amiodarone and DEA differed in their pharmacokinetic characteristics mostly due to a higher CL of DEA. With oral dosing, AM appeared to undergo significant presystemic first-pass metabolism within the intestinal tract. Copyright © 2007 John Wiley & Sons, Ltd.

A stereospecific high-performance liquid chromatographic assay was developed for the quantitation of ketoconazole enantiomers (KTZ) in rat plasma. After protein precipitation of 100 microL plasma using acetonitrile, a wash step was performed using hexane. The supernatant was removed and KTZ enantiomers and amiodarone, the internal standard, were extracted using liquid-liquid extraction with tert-butyl methyl ether. After transfer and evaporation of the organic layer, the residue was reconstituted in mobile phase and injected into the HPLC through a chiral column. The mobile phase consisted of hexane:ethanol:2-propanol with diethyl amine, pumped at 1.5 mL/min. All components eluted within 18 min. KTZ enantiomers were baseline resolved and peaks were symmetrical in appearance with no interferences. Calibration curves were linear over the range 62.5-5000 ng/mL of enantiomer. The intraday and interday CV% assessments were

To study the effect of hyperlipoproteinemia on in vitro distribution of amiodarone (AM) and its prevalent metabolite desethylamiodarone (DEA) in human and rat plasma. Human and rat normolipidemic (NL) and hyperlipidemic (HL) plasma were spiked with AM and DEA. The fractions (high and low density lipoproteins, triglyceride rich lipoproteins and lipoprotein deficient plasma) were separated using ultracentrifugation. Human and rat displayed similar patterns in terms of association of AM and DEA in NL plasma, in which the highest and lowest associations were observed in lipoprotein deficient (LPDP) and triglyceride (TRL) rich plasma fractions, respectively. In HL a substantial shift was observed in partitioning of AM and DEA mostly to TRL. The shift of AM and DEA into TRL fraction of HL plasma was more drastic for rat than human. In HL, association of AM with rat LPDP and HDL fractions were 10 and 26-fold lower than in the corresponding human fractions, respectively. The DEA:AM ratio in rat, but not human, was significantly affected by HL. HL caused a major shift of AM and DEA to TRL fraction in both species. The findings were consistent with the higher AM concentrations previously noted in HL rats given the drug.

A simple, rapid and reliable high-performance liquid chromatographic (HPLC) method was developed and validated for the determination of curcumin in rat plasma. Plasma was precipitated with acetonitrile after addition of the internal standard (IS), 4-hydroxybenzophenone. Separation was achieved on a Waters muBondapak C(18) column (3.9 x 300 mm, 5 microm) using acetonitrile (55%) and citric buffer, pH 3.0 (45%) as the mobile phase (flow rate = 1.0 mL/min). The UV detection wavelength was 300 and 428 nm for IS and curcumin, respectively. The extraction efficiencies were 97.08, 95.69 and 94.90% for 50, 200 and 1000 ng/mL of curcumin in rat plasma, respectively. The calibration curve was linear over the range 0.02-1 microg/mL with a correlation coefficient of r(2) > 0.999. The intra- and inter-day coefficients of variation were less than 13%, and mean intra- and inter-day errors were less than +/-6% at 50, 200 and 1000 ng/mL of curcumin. This assay was successfully applied to the pharmacokinetic studies of both solubilized curcumin and its polymeric micellar formulation in rats. It was found that polymeric micelles increased the half-life of curcumin 162-fold that of solubilized curcumin and increased the volume of distribution (Vd(ss)) by 70-fold.