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This open-label first-in-human study evaluated JPH203, which is a novel selective L-type amino acid transporter 1 inhibitor. We also evaluated the association between the N-acetyltransferase 2 phenotype and outcomes. Japanese patients with advanced solid tumors received daily intravenous JPH203 treatment for 7 days, followed by a 21-day rest period, at escalating doses of 12-85 mg/m 2 . Dose-limiting toxicities were evaluated during the first cycle using a 3 + 3 design. The study enrolled 17 patients, although grade 3 liver dysfunction was detected in one of six patients receiving 60 mg/m 2 and in the first patient to receive 85 mg/m 2 . Further enrollment was terminated and the maximum tolerated dose was defined as 60 mg/m 2 . The AUC ∞ increased between 12 mg/m 2 and 25 mg/m 2 , although no differences were observed at 25-40 mg/m 2 . Partial response was observed for one patient with biliary tract cancer (BTC) at the 12 mg/m 2 dose, and disease control was achieved by 3 of 6 patients at the 12 mg/m 2 and 25 mg/m 2 dose levels. Based on these results, we recommend a phase II dose of 25 mg/m 2 . The disease control rate for BTC was 60%. Two patients with grade 3 liver dysfunction had the rapid N-acetyltransferase 2 phenotype, and disease control was more common for the non-rapid phenotype (50% vs. 12.5%). It appears that JPH203 was well-tolerated and provided promising activity against BTC. The N-acetyltransferase 2 phenotype might help predict the safety and efficacy of JPH203. Clinical trial registration: UMIN000016546.

Pharmacokinetic profiles of pemafibrate with virtual drug and/or disease interactions were assessed by creating a detailed physiologically based pharmacokinetic (PBPK) model.Passive diffusion clearance in liver was experimentally determined as 0.013 mL/min/10 6 human hepatocytes. In vitro intrinsic clearance values for pemafibrate by cytochromes P450 2C8, 2C9, and 3A4 were 54, 26, and 16 μL/min/mg protein, respectively. Values for the effective permeability and the intrinsic clearance of hepatic uptake by organic anion transporting polypeptide (OATP) 1B1 were optimized in a simulator platform.This PBPK model was subsequently validated using reported maximum pemafibrate plasma concentration and area under the curve values in reported interaction studies in healthy subjects co-administered with rifampicin.For subjects with Child-Pugh A and B liver cirrhosis, the intrinsic clearance of hepatic uptake of pemafibrate by OATP1B1 were modeled using 53% and 31% of that of healthy subjects, respectively. Virtual co-administrations of rifampicin and sacubitril (OATP1B inhibitors) in subjects with renal impairment and liver cirrhosis resulted in 11- to 13-folds (rifampicin) and 1.1- to 1.3-folds (sacubitril) increased plasma exposures of pemafibrate.The current PBPK model and simulations revealed different pharmacokinetic profiles for pemafibrate following co-administration of rifampicin or sacubitril in virtual subjects with or without renal/hepatic impairment.

In vitro permeability and in vivo pharmacokinetics of pemafibrate were investigated in human intestinal and animal models untreated or pretreated with cyclosporine A or rifampicin to evaluate any drug interactions. Ratios of basal to apical apparent permeability (P app ) over apical to basal P app in the presence of pH gradients decreased from 0.37 to 0.080 on rifampicin co-incubation, suggesting active transport of pemafibrate from basal to apical sides in intestinal models. Plasma concentrations of intravenously administered pemafibrate were enhanced moderately in control mice but only marginally in humanized-liver mice by oral pretreatment with rifampicin [an organic anion transporting polypeptide (OATP) 1B1 inhibitor] 1 h before the administration of pemafibrate. In three cynomolgus monkeys genotyped as wild-type OATP1B1 (2 homozygous and 1 heterozygous), oral dosing of cyclosporine A 4 h or rifampicin 1 h before pemafibrate administration significantly increased the areas under the plasma concentration-time curves (AUC) of intravenously administered pemafibrate by 4.9- and 7.4-fold, respectively. Plasma AUC values of three pemafibrate metabolites in cynomolgus monkeys were also increased by cyclosporine A or rifampicin. These results suggested that pemafibrate was actively uptaken in livers and rapidly cleared from plasma in cynomolgus monkeys; this rapid clearance was suppressible by OATP1B1 inhibitors., Competing Interests: Declaration of competing interest S.O. is a visiting scientist in academia and works for Kowa Co., the manufacturer of pemafibrate. The other authors declare that there are no conflicts of interest., (Copyright © 2020 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Background: Pemafibrate, a novel selective peroxisome proliferator-activated receptor-α modulator, is prescribed for patients with dyslipidemia. To investigate other potential nonlipid-related effects of pemafibrate, the sensitive and rapid quantitation method for pemafibrate was required. Results: The developed LC-MS/MS assay method exhibited excellent accuracy, precision, sensitivity, stability, no matrix effect and high recovery. The LOQ (0.05 ng/ml) and run time (6.0 min) were superior to previous reports. The calibration curve showed good linearity over the wide concentration range (0.05-100.00 ng/ml). This validated method was successfully applied in a rat pharmacokinetic study using lower doses (0.02 or 0.10 mg/kg) than have been previously reported. Conclusion: This method can support gathering data for the evaluation of pemafibrate in future studies.

BACKGROUNDThe hereditary transthyretin (TTR) amyloidoses are a group of diseases for which several disease-modifying treatments are now available. Long-term effectiveness of these therapies is not yet fully known. Moreover, the existence of alternative therapies has resulted in an urgent need to identify patient characteristics that predict response to each therapy.METHODSWe carried out a retrospective cohort study of 210 patients with hereditary TTR amyloidosis treated with the kinetic stabilizer tafamidis (20 mg qd). These patients were followed for a period of 18-66 months, after which they were classified by an expert as responders, partial responders, or nonresponders. Correlations between baseline demographic and clinical characteristics, as well as plasma biomarkers and response to therapy, were investigated.RESULTS34% of patients exhibited an almost complete arrest of disease progression (classified by an expert as responders); 36% had a partial to complete arrest in progression of some but not all disease components (partial responders); whereas the remaining 30% continued progressing despite therapy (nonresponders). We determined that disease severity, sex, and native TTR concentration at the outset of treatment were the most relevant predictors of response to tafamidis. Plasma tafamidis concentration after 12 months of therapy was also a predictor of response for male patients. Using these variables, we built a model to predict responsiveness to tafamidis.CONCLUSIONOur study indicates long-term effectiveness for tafamidis, a kinetic stabilizer approved for the treatment of hereditary TTR amyloidosis. Moreover, we created a predictive model that can be potentially used in the clinical setting to inform patients and clinicians in their therapeutic decisions.

Background: Astragalosidic acid (LS-102) is a new water-soluble derivative of astragaloside IV - a major effective component isolated from the Chinese herb Astragali Radix. Our previous study showed that LS-102 exhibited potent cardiovascular activity., Purpose: The objective of this study was to investigate the pharmacokinetic properties of LS-102 after single-dose, oral administration in beagle dogs by developing and validating an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method., Method and Result: The chromatographic separation was performed on a Acquity HSS C 18 column (100 mm × 2.1 mm, 1.8 µm) by a gradient elution using a mobile phase consisting of water and acetonitrile at a flow rate of 0.35 ml/min. The analytes were detected with a triple quadrupole tandem mass spectrometry in multiple reaction monitoring mode. Method validation revealed a wide linearity over the range of 2.0-10,000 ng/ml together with satisfactory intra- and inter-day precision, accuracy, and recovery. Stability testing showed that LS-102 spiked into dog plasma was stable for 4 h at room temperature, for up to 2 weeks at -80 °C, and during three freeze-thaw cycles. The method was effectively and successfully applied to the pharmacokinetics of LS-102 after oral administration (5, 10 and 20 mg/kg) to beagle dogs. Peak plasma concentrations are attained within approximately 2 h after oral administration with a half-life ranging from 1.55 h to 4.49 h. The plasma concentration-time curve of LS-102 after oral administration presents the phenomenon of a double-peak absorption phase. The peak concentration and area under the concentration-time curve of LS-102 seemed to increase with the increasing doses proportionally, that suggesting linear pharmacokinetics in dogs. Meanwhile, the doxorubicin (Dox)-injured H9c2 cell model was prepared by incubating the cells in 1 µM Dox for 24 h. MTT assay and LDH release measurement showed that LS-102 protected against Dox-induced cardiomyocyte death., Conclusion: The obtained results may help to guide the further pre-clinical research of LS-102 as a potentially novel cardioprotective agent., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Tafamidis is a first-in-class inhibitor of transthyretin amyloid fibril formation. It has been available in Argentina, Japan, and Mexico for the treatment of transthyretin amyloidosis in adult patients with early-stage symptomatic polyneuropathy. In this study, a rapid and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for the assay of tafamidis in rat plasma. The method was also assessed for its applicability to pharmacokinetic studies in rats. Tafamidis was extracted from rat plasma by the liquid-liquid extraction method using hydrochloric acid and ethyl acetate. A reversed-phase C18 column and a mobile phase consisting of 10mM ammonium formate and acetonitrile were used to achieve chromatographic separation. The flow rate for the mobile phase was set at 0.3mL/min. Tafamidis and 2-CBC, which was used as the internal standard (IS), were analyzed by multiple reaction monitoring in negative ESI mode at m/z transitions of 305.4→261.4 for tafamidis and 271.7→227.8 for the IS. The lower limit of quantification of tafamidis was obtained as 3ng/mL, and the calibration curve was linear over a concentration range of 3-3000ng/mL (R 2 >0.99). The validation parameters investigated, which were specificity, precision, accuracy, matrix effect, recovery, and stability, were well within acceptable limits. The method was successfully used for the evaluation of the pharmacokinetics of tafamidis in rats., (Copyright © 2017 Elsevier B.V. All rights reserved.)

MLN0128, an mTOR kinase inhibitor, is currently undergoing clinical investigation for treatment of a variety of cancers. To support this work, an LC-MS/MS method has been developed for the determination of MLN0128 in human plasma. A structural analog STK040263 was used as the internal standard. Both MLN0128 and the IS were first extracted from plasma using methyl tert-butyl ether; then separated on a Waters XTerra® MS C 18 column using a mobile phase consisting of methanol-acetonitrile-10.0 mm ammonium formate (34:6:60, v/v/v) at a flow rate of 0.300 mL min -1 . Quantitation of MLN0128 was done by positive electrospray ionization tandem mass spectrometry in multiple-reaction-monitoring mode. This method has a total run time of <4 min with the retention times of 1.95 and 2.94 min for the IS and MLN0128, respectively. The method has been validated per the US Food and Drug Administration guidance for bioanalytical method validation. It has a calibration range of 0.100-50.0 ng mL -1 in human plasma with a correlation coefficient > 0.999. The overall assay accuracy and precision were ≤ ± 4 and ≤8%, respectively. The IS normalized recovery of MLN0128 was 98-100%. The stability studies showed that MLN0128 was stable under all tested conditions. The method developed may be useful for clinical studies of MLN0128., (Copyright © 2016 John Wiley & Sons, Ltd.)

Placebo-controlled clinical trials are useful for identifying the dose of a drug candidate that produces a meaningful clinical response in a patient population. Currently, Pfizer, Inc. is enrolling a 400-person clinical trial to test the efficacy of 20 or 80 mg of tafamidis to ameliorate transthyretin (TTR)-associated cardiomyopathy using clinical endpoints. Herein, we provide guidance for how to optimize the dose of tafamidis for each WT TTR cardiomyopathy patient using its mechanism of action as the key readout, i.e. we identify the dose of tafamidis that maximally kinetically stabilizes TTR in the blood. Tetramer dissociation is rate limiting for TTR aggregation, which appears to drive the pathology of the TTR amyloidoses. Hence, we measure the TTR tetramer dissociation rate (kinetic stability) in the patient's plasma as a function of tafamidis dose to optimize the dose employed to maximize kinetic stability. Historical data tell us that a subset of patients exhibiting higher tafamidis plasma concentrations are maximally kinetically stabilized at the 20-mg tafamidis dose, whereas the patient studied herein required a 60 mg once daily dose to achieve maximum kinetic stabilization. We anticipate that establishing the dose of tafamidis that achieves maximal TTR kinetic stabilization will translate into a maximal clinical effect, but that remains to be demonstrated.

Many primary human tumors and tumor cell lines highly express human L-type amino acid transporter 1 (hLAT1); cancerous cells in vivo are strongly linked to LAT1 expression. Synthetic chemistry and in vitro screening efforts have afforded a variety of novel and highly hLAT1 selective compounds, such as JPH203 1. In a recent report, we demonstrated that 1 has potent in vitro and in vivo activity. JPH203 was intravenously administered to produce significant growth inhibition against HT-29 tumors transplanted in nude mice. The current work develops a robust LC/MS-MS method to monitor 1 and its major Phase II metabolite N-acetyl-JPH203 2 from biological samples. We have conducted in vitro and in vivo experiments and the major scientific findings are: i) the major route of biotransformation of 1 is Phase II metabolism to produce 2; ii) metabolite 2 is formed in various organs/tissues (i.e. blood, liver, kidney); and iii) as dogs, which are deficient in NAT genes, do not produce 2, the dog will not be an appropriate toxicological model to evaluate 1.

To objective of this work was to study the feasibility of iontophoretic delivery of SLV 318 (7-(4-benzyl-1-piperazinyl)-2(3H)-benzoxazolone methanesulfonate) across hairless rat skin in vitro and in vivo. The effect of counter-ions and temperature were investigated for optimizing SLV 318 solubility. The effect of electrode efficiency and total current applied on the delivery of SLV 318 were studied using Franz diffusion cells and samples were analyzed using HPLC. Delivery increased with increasing concentration. For current-time combinations, electrode had to be replaced every 9h. Passive, iontophoretic (0.1 mA/cm(2) for 1h) and intravenous studies were performed in vivo. Blood samples collected were analyzed using LC-MS/MS. SLV 318 had higher solubility with NaCl (75 mM) as a counter-ion at 25°C than with other counter-ions tested. In vivo iontophoresis significantly enhanced the permeation and also reduced its lag time (P<0.05). The C(max) of SLV 318 during 1h iontophoresis was 6.56 ± 0.68 ng/mL at 1.31 ± 0.29 h (T(max)) as compared to 2.96 ± 0.29 ng/mL at 25.32 ± 0.67 h (T(max)) by 24h passive permeation. The in vitro and in vivo data has shown the feasibility to enhance delivery of SLV 318 by iontophoresis., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Two highly deuterium-labeled compounds, (R)-K-13675-d(11) and (R)-K-13675-d(7), were prepared for use as internal standards for low-level quantification of plasma drugs by LC/MS/MS. We successfully demonstrated their utility in pharmacokinetic studies for sensitive and precise drug quantification.

We have determined the fluorescence characteristics of two long wavelength dyes, albumin blue 633 (AB633) and 670 (AB670), in plasma and blood to evaluate the possibility of making direct fluorescence sensing measurements in blood. Using binding and lifetime measurements we were also able to show that these dyes bind selectively to human serum albumin (HSA) in plasma and blood. By measuring changes in the mean lifetime of AB670 with changes in the HSA concentration, we showed that lifetime-based sensing can be used to monitor HSA concentrations using these albumin blue dyes. Anisotropy measurements for AB633 and AB670 in plasma and blood revealed high anisotropy values for these dyes in these media. Exploiting these high anisotropies, we were also able to determine HSA concentrations in plasma and blood mimics using changes in AB670 anisotropy with HSA concentration. These results show that, apart from being able to make fluorescence measurements directly in plasma and blood, it is possible to sense directly for specific plasma/blood components using fluorescent probes that bind preferentially to them.

Ontazolast is a potent inhibitor (IC50 = 1 nm) of calcium ionophore A23187-stimulated leukotriene B4 (LTB4) biosynthesis in human peripheral blood leukocytes. The compound is practically insoluble in water (0.14 microgram/mL) and previous studies in animals have demonstrated extensive presystemic drug clearance through hepatic first-pass metabolism. Bioavailability of a suspension formulation in rats was less than 1%, but increased to approximately 9% when administered as a 20% soybean oil-in-water emulsion. The emulsion formulation and three additional lipid-based formulations were administered by gavage to conscious, minimally restrained rats in a novel, double-cannulated model to determine the effects of formulation on systemic blood absorption and mesenteric lymph transport of ontazolast. The bioavailability of ontazolast was significantly and substantially enhanced by all of the lipid-based formulations. While these formulations also significantly increased the amount of ontazolast transported by the lymph, the total amounts transported were insufficient to account for the improvement in bioavailability, which may be due to the elimination or reduction of the barriers of poor aqueous solubility and slow dissolution to absorption of ontazolast from the gastrointestinal tract, or the effects of lipid on the gastrointestinal membrane permeability, transit time, or metabolism of ontazolast. Semisolid SEDDS formulations, composed of Peceol and Gelucire 44/14, produced bioavailability similar to the emulsion formulation. The total amount of ontazolast transported by the lymph varied directly with the amount of concurrent triglyceride transport and appeared to be favored by formulations that prolong gastric emptying time or promote rapid absorption of ontazolast from the gastrointestinal tract.

A sensitive high-performance liquid chromatographic (HPLC) method was developed and validated to separate and quantitate the levels of L-696,229 (I), a novel human immunodeficiency virus type I non-nucleoside reverse transcriptase inhibitor, and its hydroxy metabolites (II and III) in plasma samples. The procedure involves the addition of a constant known quantity of internal standard to the biological specimen followed by extraction of the compounds of interest into methyl tert.-butyl ether. The organic phase is evaporated to dryness under a gentle stream of nitrogen. The residue is then dissolved in methanol and water and injected onto a reversed-phase HPLC column. A gradient HPLC method is used to elute the compounds which are monitored using UV detection at 319 nm. Absolute calibration factors (from the standard curve) were calculated by analyzing standards, and these factors were used to determine the concentration of drug (I) and its hydroxy metabolites (II and III) in the samples using the internal standard method. The method was linear using a standard concentration range of 50 to 20,000 ng/ml. The limit of quantitation was 50 ng/ml using 200 microliters plasma. The procedure was utilized to monitor plasma levels of I, II and III in acute and chronic toxicity studies in several animal species.

L-697,661 is a non-nucleoside analogue with potent, selective inhibitory activity against the reverse transcriptase of human immunodeficiency virus type 1 (HIV-1). The present study evaluated the potential role of this compound in the treatment of HIV-1-infected patients in a double-blinded, placebo- and zidovudine-controlled trial using plasma viremia as a marker of antiviral activity and real-time phenotypic evaluation of viral isolates for the emergence of resistance. Participants received 12 weeks of either placebo, 25 mg twice a day, 100 mg three times a day, or 500 mg twice a day of L-697,661, or zidovudine, 100 mg five times a day. Mean logarithmic reciprocal titers of plasma virus in patients taking either L-697,661 or zidovudine decreased by week 4 of therapy; for L-697,661 recipients these changes were dose-dependent and, at the highest dose tested, were comparable in magnitude to those seen with zidovudine. Viral suppression induced by L-697,661 persisted through 8 weeks of treatment but decreased by week 12. This rebound paralleled emergence of viral isolates showing resistance to L-697,661. We conclude that although L-697,661 has potent antiretroviral activity in vivo, its utility may be compromised by rapid emergence of L-697,661-resistant virus. Plasma viremia is a highly sensitive technique affording considerable utility in the early testing of such agents.

A method for the determination of a 2-pyridinone-based specific HIV-1 reverse transcriptase inhibitor in human plasma is described. Plasma samples are extracted using phenyl solid phase extraction columns. The extract is analyzed via HPLC using a column-switching system to remove interferences from late-eluting endogenous components. Detection is based on UV absorbance at 314 nm. The assay was linear in the concentration range of 10-500 ng/ml, when 1-ml aliquots of plasma were extracted. The mean precision of the assay, expressed as the coefficient of variation, was 3.8%. The assay has been validated and utilized to support human pharmacokinetic studies.

A rapid method for measuring pyridinone HIV-1 reverse transcriptase inhibitor plasma levels was necessary for identifying potential clinical candidates and for choosing a clinical formulation. Due to its sensitivity to the pyridinones, ability to tolerate extraneous material, and its capability for rapid, high through-put screening, the HIV-1 RT assay was developed into a bioassay for determining plasma levels of the pyridinones in Rhesus monkey plasma. With this assay, dose proportionality of L-697, 639 was established. Formulation studies using L-697, 639 indicated that the plasma levels achieved in Rhesus monkeys with the clinical formulation (peak levels = 3.9 microM at 30 min) fall between the levels achieved with polyethylene glycol 300 and hydroxypropyl methyl cellulose formulations (peak levels = 8.9 microM and 0.4 microM respectively, at 60 min). Two other pyridinones, L-696, 229 and L-697, 661, administered as the clinical formulation, had peak plasma levels of 1.6 microM (30 min) and 0.3 microM (60 min), respectively. In Rhesus monkeys, the bioavailabilities of these compounds (administered as the clinical formulation) ranged from 11 to 24% and their half-life values ranged from 24 to 120 min. The results of oral studies in Rhesus monkeys with these compounds were very similar to initial results of studies in humans.

A method for the determination of a non-nucleoside HIV-1 reverse transcriptase inhibitor in human plasma is described. Plasma samples are extracted using phenyl solid-phase extraction columns. The extract is analyzed by high-performance liquid chromatography with a polybutadiene-coated alumina column and a mobile phase of methanol-0.025 M pH 8 dibasic sodium phosphate buffer (1:1, v/v). Detection is based on ultraviolet absorbance at 326 nm. The assay was validated in the concentration range 10-500 ng/ml when 1-ml aliquots of plasma are extracted. The assay has been utilized to support human pharmacokinetic studies.

A rapid and sensitive method of extraction of human plasma containing acetaminophen, chlorzoxazone, oxyphenbutazone and diazepam along with their active metabolites was developed. The plasma samples were extracted by a solid-phase extraction procedure with theophylline as an internal standard for accurate quantitation. The reversed-phase liquid chromatographic method provided a linear ultraviolet detector response in the range 100.0-700.0 ng/ml. Recoveries greater than 95% were achieved from human plasma samples. Limits of detection of 100, 200, 150 and 250 ng/ml for acetaminophen, chlorzoxazone, oxyphenbutazone and diazepam, respectively, were obtained.

Flunoxaprofen is a new nonsteroidal antiinflammatory agent that, like benoxaprofen, inhibits leukotriene rather than prostaglandin synthesis. The absorption and disposition kinetics of flunoxaprofen and benoxaprofen have been compared in six healthy volunteers after oral administration of 100 mg of each drug. The two drugs showed similar absorption characteristics, whereas the distribution and elimination processes were much faster for flunoxaprofen. The renal route of elimination appeared to contribute significantly less to the disposition of flunoxaprofen. These kinetic characteristics render less likely the risk of excessive drug accumulation with flunoxaprofen, especially in the presence of reduced renal function.

The absorption and disposition kinetics of the enantiomers of the nonsteroidal antiinflammatory drug flunoxaprofen were studied in six healthy volunteers after oral administration of either R,S(+/-)-flunoxaprofen or R(-)-flunoxaprofen. The apparent values of the volume of distribution and systemic clearance of the S(+)-enantiomer were significantly lower than those of the R(-)-enantiomer. There was no significant difference in the absorption and elimination half-lives between the two isomers. The S(+)- to R(-)-isomer plasma concentration ratio increased with time with an apparent inversion half-time of about 50 h. This observation suggests metabolic inversion of R(-)- to S(+)-enantiomer, although the possibilities of stereoselective bioavailability or interaction between the two isomers can not be excluded.

A total of 30 patients participated in a double-blind crossover trial to compare the efficacy and safety of benoxaprofen with naproxen in the treatment of osteoarthritis. Benoxaprofen, 600 mg administered once daily, was as effective as naproxen, 250 mg administered twice daily. Adverse reactions were mostly mild to moderate in severity and the incidence of the reactions was similar for the 2 study drugs. The advantage of the once-a-day dose regimen of benoxaprofen is discussed.

The pharmacokinetics of benoxaprofen in therapeutic doses of 400 or 600 mg as a solution, capsule or tablet were determined in 44 men after single or multiple doses. The plasma levels of the drug after oral administration of a solution best fitted a 2-compartment open pharmacokinetic model, whereas the levels after the solid dosage forms more appropriately fitted the simple 1-compartment open model. The plasma elimination half-life of the drug, when in solid dosage form, was found to be in the range of 19-26 h, justifying once-a-day dosage. Steady state levels of benoxaprofen were obtained after the 5th dose of a 400 mg capsule every 24 h.

This multicenter double-blind clinical trial compared the efficacy and safety of benoxaprofen and naproxen in the treatment of rheumatoid arthritis. The studies followed a crossover design which provided 6 wk therapy with each of the 2 study drugs. Benoxaprofen at a single daily dose of 600 mg compared favorably to naproxen, 750 mg, administered in 2 equally divided doses. All efficacy results indicated slightly more improvement with benoxaprofen although the difference between the 2 drugs was not significant. Side effects were generally mild and only 1 patient discontinued benoxaprofen therapy because of a reactivation of a duodenal ulcer.

Benoxaprofen is a new nonsteroidal analgesic anti-inflammatory drug with a long half-life. Preliminary studies showed that steady-state blood levels could be achieved within 24 hours of treatment using a dose of 300 mg on the first day followed by 100 mg twice daily. A double-blind cross-over trial showed that benoxaprofen was effective and well tolerated in rheumatoid arthritis. Its analgesic effect was not apparent until the sixth day of treatment. An unusual trial design was used with treatment periods of unequal duration. This design has the advantage of allowing a new drug to be given for long enough to determine the time course of its action, while sparing patients prolonged treatment with placebo.

Benoxaprofen, 400 to 600 mg daily, was compared to aspirin, 4,000 to 6,000 mg daily, or ibuprofen, 1,600 to 2,400 mg daily, in 2 multicolor clinical trials. The study design was double-blind and provided 28 wk of active drug therapy. Statistical analysis of the results showed benoxaprofen to be at least as effective as the 2 control drugs. More patients taking ibuprofen or aspirin discontinued therapy than patients taking benoxaprofen. Side effects occurred more frequently and lasted longer in patients who took aspirin during the study. Clinical laboratory examinations supported the long-term safety of benoxaprofen.

The present experiments evaluated in rats the effects of prenatal and postnatal exposure to a non-steroidal antiinflammatory agent, flunoxaprofen (5-10 and 20 mg/kg/day by the oral route), on cardiovascular function in the pups. In both conscious and anaesthetized rats pre- and postnatal flunoxaprofen exposure at the 30th and 60th day of age, significantly (P less than .05) induced a decrease of pressor response to carotid-sinus baroreceptor stimulation and to L-noradrenaline (0.1-1 and 5 micrograms/kg iv), and an increase of the hypotensive responses to L-isoprenaline (0.01-0.1 and 1 microgram/kg iv) and acetylcholine (0.01-0.1 and 1 microgram/kg iv). These effects were not observed in rats on the 90th day of age. Moreover, pre- and postnatal flunoxaprofen exposure did not modify systolic arterial blood pressure of plasma levels of catecholamines and acetylcholinesterases. Our results also show that in normotensive rats flunoxaprofen exposure during pregnancy did not affect the body weight, systolic or diastolic blood pressure or heart rate of pregnant rats. It did not affect the length of gestation, number of pups per litter or pup body weight. No macroscopic teratogenic effects were observed.

Plasma kinetics and 24 h urinary elimination of flunoxaprofen, a nonsteroidal antiinflammatory drug, were studied in 23 elderly patients (mean age 69.9 years) and compared with the data obtained in four young volunteers. The drug was administered as a single oral 100 mg tablet and its plasma and urine concentrations were assayed by a high performance liquid chromatography method. Plasma kinetics fitted a 3-exponential equation with a mean half-life of 7.9 +/- 2.17 hours and a mean peak plasma of 8.5 +/- 2.97 micrograms/ml, which was observed at about the second hour. The values of the areas under the curves (AUC) and the values of total clearance (multiplied by the bioavailability) showed great variability, due to the large differences in the patients body weights; in fact the value of AUC was linearly correlated to the dose divided by the body weight. The mean residence time (MRT) of the drug in plasma was equal to 12.81 h. Low amounts of unmodified drug (about 10%) were found in 24 h urine sample, indicating a high degree of biotransformation. Small differences only were found in plasma kinetics of flunoxaprofen among the present group of elderly patients and the group of four young volunteers; the main difference corresponded to a slower rate of gastrointestinal absorption and to a longer mean residence time.

Benoxaprofen did not impair platelet function or platelet prostaglandin synthesis in vivo or in vitro in contrast to indomethacin, a known prostaglandin synthesis inhibitor. Platelet cyclic AMP levels were not changed by either drug in vivo or in vitro. The results of routine tests for hemostatic function (template bleeding time and blood clotting assays) were not changed by either drug. A trend towards inhibition of cAMP-dependent protein kinase by benoxaprofen was observed. The significance of this observation, if valid, remains obscure. These studies suggest that benoxaprofen, which does not appreciably suppress hemostatic function, may be used safely in patients with acquired or congenital coagulation defects (e.g. patients receiving oral anticoagulant, hemophiliacs with arthropathy).

A double-blind within-patient crossover trial compared the new nonsteroidal antiinflammatory agent benoxaprofen with ibuprofen in the treatment of osteoarthritis in 31 patients. Both benoxaprofen (600 mg once daily) and ibuprofen (400 mg qid) improved measurements of pain, stiffness, range of movement, mobility, patient preference, and overall assessment. However, the improvement was statistically significant only for pain at rest and range of knee movement for both drugs and for range of hip movement (N = 8) for ibuprofen. There was no statistically significant difference between treatments with the 2 drugs. Six patients taking benoxaprofen reported skin irritation on exposure to sunlight.

A method for the high-pressure liquid chromatographic determination of chlorzoxazone and its hydroxy metabolite in human plasma samples is presented. The separation of the compounds is achieved on an octadecylsilane column with a mobile phase of absolute methanol-distilled water (40:60) at a flow rate of 2.0 ml/min (3100 psig). The chromatographic separation is achieved within 10 min. The overall analysis time is about 45 min, which includes extraction of the drug and metabolite from plasma followed by high-pressure liquid chromatographic separation and quantification. The accuracy of the procedure is in the 1-5% range.

The pharmacokinetic profile of benoxaprofene, administered in a single oral dose of 600 mg, has been determined comparatively in 5 normal subjects and 15 patients with renal insufficiency (five of whom were on chronic hemodialysis). In the normal subject, the half-absorption time (Ka) was 0.63 hours; a mean theoretical maximal concentration of 47.3 micrograms/ml was reached 3.6 hours after administration of the drug. The decrease in serum levels was particularly slow, the coefficient of total elimination (Ke) being 0.0241(h-1) and the biological half-life attaining 28.8 hours. :The total clearance (Ct = 4.8 ml/min/1.73 m2) and renal clearance (Cr =1.6 ml/min/1.73 m2) values were low. 13.9% of the ingested dose of benoxaprofene was recovered in the 24 hours urinary volume. Renal insufficiency does not significantly change the pharmacokinetic parameters. It appears advisable to reduce the dosage by half only in patients with a Cr clearance of less than 10-20 ml/min/1.73 m2. The theoretical serum values reached after administration of 600 mg benoxaprofene repeated every 6-12-24-36 or 48 hours have been calculated and it has been found that effective concentrations can be obtained by administration of 600 mg every 12 or 24 hours.

The enantiomeric composition of benoxaprofen [(RS)-2-(P-chlorophenyl)-alpha-methyl-5-benzoxazoleacetic acid] in plasma and urine was determined after oral administration of both the racemic mixture and the (R)-(-)-enantiomer to normal human volunteers. Resolution of the diastereomeric amides, formed by the reaction of the enantiomers with (S)-(-)-apha-methylbenzylamine, was accomplished by gas chromatography. The (R)-(-1)-enantiomer of the parent drug was stereoselectively inverted to its (S)-(+) isomer in humans.

Benoxaprofen, a novel anti-inflammatory compound, is efficiently (greater than 95%) extracted from plasma and urine in the pH range 1 to 5 into either chloroform or ether. The compound is determined either by UV spectroscopy or by gas-liquid chromatography of the methyl ester (formed by reaction with diazomethane) on a column of 3% of silicone gum E-301 on DCMS-treated Chromosorb W, with detection by flame ionisation (limit 0.3 microgram/ml) or electron capture (limit 0.01 microgram/ml). For rapid routine use, the UV method (limit ca. 5 microgram/ml) gives good agreement with the specific methods.

A clinical study on normal volunteers was performed in order to establish the pharmacokinetic pattern of the non-steroidal antiinflammatory drug S-(+)-2-(4-fluorophenyl-a-methyl-5-benzoxazole-acetic acid (flunoxaprofen, Priaxim, FLU) after oral administration or after transcutaneous absorption. Six subjects (3 men and 3 women) received FLU orally (a single dose of 200 mg) and 6 subjects (4 men and 2 women) were treated by cutaneous application on the shoulder of 1.5 g of a gel preparation containing FLU 5%. Blood samples were withdrawn before and at several time intervals after the treatments up to 48 h after oral administration and up to 24 h after cutaneous application. Serum FLU concentrations were determined by a HPLC method. The results show that a single oral dose of FLU 200 mg follows a kinetic pattern very similar to that obtained with a 100 mg dose as referred to in the literature, without significant differences of t1/2 beta, Vd and clearance values in comparison with those after FLU 100 mg. The dose-related parameters (Cmax and AUC) were higher after FLU 200 mg than after FLU 100 mg. The cutaneous application of a flunoxaprofen gel preparation did not cause detectable systemic absorption of the drug. In conclusion FLU shows favourable pharmacokinetic parameters after 200 mg oral dose, since serum values of the drug exclude the risk of accumulation; moreover the topical application of a FLU gel preparation is a safe transcutaneous treatment for inflammation and pain due to lacking systemic absorption of the drug.

The kinetics of flunoxaprofen, an anti-inflammatory nonsteroidal drug, was studied in rats (Charles River), dogs (beagles), and monkeys (Macaca fascicularis). Plasma levels, after oral and iv administration of 20-40 mg/kg, and urinary excretion were followed for 24-72 h; the determinations were performed by gas chromatography. Levels in various organs and in rat bile were also determined. The pharmacokinetic parameters show noteworthy similarities in the three species studied: high bioavailability, extensive biotransformations with small urinary excretion of unmodified drug, total clearance between 40 and 50 mL/h/kg, and peak plasma levels of approximately 200 micrograms/mL. Rats show a high value in volume of distribution (2 L/kg), whereas dogs and monkeys show a volume of distribution between 0.13 and 0.18 L/kg. In the rat, the half-life of the drug is approximately 70 h, whereas in the dog and monkey, a half-life of approximately 2 h was found.