Human pharmacokinetics and interconversion of enantiomers of MK-0767, a dual PPARalpha/gamma agonist.

MK-0767, a dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist, has been studied as a potential treatment of type 2 diabetes and dyslipidemia. The pharmacokinetics and interconversion of (+)-(R)-MK-0767 and (-)-(S)-MK-0767 were evaluated following oral administration of each single enantiomer and the racemate to healthy subjects. The results demonstrate that, consistent with in vitro experiments, chiral inversion occurs rapidly in vivo, and interconversion equilibrium favors (+)-(R). After all treatments, a stable ratio (R/S) of 2 to 2.5 was achieved within 8 hours in most individuals, congruent with model-based estimates of interconversion half-life. In addition, the pharmacokinetics of each enantiomer were generally similar regardless of treatment. Modeling and simulation of enantiomer disposition suggest that the observed predominance of (+)-(R)-MK-0767 in plasma may result from differential volumes of distribution between (-)-(S) and (+)-(R), preferential conversion from (-)-(S) to (+)-(R), or a combination of these, but not faster clearance of (-)-(S) compared to (+)-(R).

Effect of aprepitant on the pharmacokinetics of intravenous midazolam.

Oral aprepitant 125 mg, an antiemetic and a moderate inhibitor of the metabolism of oral midazolam, was assessed for interaction with intravenous midazolam in 12 subjects randomized to intravenous midazolam 2 mg +/- oral aprepitant 125 mg. The hypothesis was that midazolam AUC would not change by more than 2-fold (consistent with no more than weak inhibition) when midazolam + aprepitant was compared with midazolam alone. An AUC geometric mean ratio (midazolam + aprepitant/midazolam) with 90% confidence interval upper bound < or =2.0 (an increase in midazolam felt to be of modest clinical significance in the highly monitored perioperative period) was prespecified. Aprepitant increased intravenous midazolam AUC(0-infinity) 1.47-fold (90% confidence interval, 1.36-1.59), which fell within the prespecified criterion.

A dual PPAR alpha/gamma agonist increases adiponectin and improves plasma lipid profiles in healthy subjects.

BACKGROUND: The objective of these studies was to evaluate the pharmacokinetics and pharmacodynamics of MK-0767, a prototypical dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist, following administration of single and multiple oral doses in healthy male subjects. METHODS: The first study was a double-blind, randomised, placebo-controlled, alternating two-panel, rising dose protocol in which single doses of 1-80 mg of MK-0767 were administered. The second study was a double-blind, randomised, placebo-controlled, staggered incremental dose, parallel-group protocol in which multiple doses of 0.3-25 mg of MK-0767 were administered once daily for 14 days. In both studies at each dose level, six subjects received MK-0767 and two subjects received placebo. RESULTS: Plasma area under the concentration-time curve and maximum plasma concentration increased with single and multiple doses of MK-0767 over the dose ranges studied. The apparent terminal half-life of MK-0767 averaged approximately 36 hours following single and multiple doses. Steady-state plasma concentrations were achieved following approximately 8 days of multiple doses. Compared with placebo, MK-0767 produced dose-dependent reductions in triglycerides (-26 +/- 8% [p = 0.002] and -33 +/- 13% [p = 0.008]) and free fatty acids (-50 +/- 11% [p < 0.001] and -67 +/- 23% [p = 0.008]) following single and multiple doses, respectively. Significant (p < or = 0.050) dose-dependent alterations in adiponectin (332 +/- 36%), low-density lipoprotein cholesterol (-29 +/- 5%), total cholesterol (-19 +/- 3%), non-high-density lipoprotein cholesterol (-28 +/- 4%), and fasting plasma glucose (-6 +/- 2%; only in the 25 mg group) were observed after multiple doses. CONCLUSIONS: The observed effects of MK-0767 on adiponectin, free fatty acids and lipids, even after single doses, demonstrate that this prototypical dual PPAR alpha/gamma agonist has clinically meaningful activity in vivo.

Quantitative determination of a novel dual PPAR alpha/gamma agonist using on-line turbulent flow extraction with liquid chromatography-tandem mass spectrometry.

Turbulent flow chromatograph (TFC) is a technique for the direct and efficient analysis of drugs and metabolites in biological matrices. We report here TFC on-line with an HPLC-MS/MS assay for the determination of 5-[2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[(4-trifluoromethyl)phenyl]methyl]benzamide (I, MK-0767, KRP297, Fig. 1) in plasma. Samples were transferred using an automated system followed by the addition of internal standard (II), prepared in 0.1 M ammonium acetate (pH 4.0). The plasma samples were directly injected onto a C18 turbulent flow column on-line with an HPLC-MS/MS system, and the analytical column used was a ThermoHypersil Keystone C18. Detection was achieved by MS/MS, using positive ionization on a TurboIonSpray probe, operated in multiple reaction monitoring (MRM) mode. The linear range was 4-2000 ng/mL for I when using 50 microL of plasma. The method exhibited good linearity and reproducibility. The method also showed good selectivity and ruggedness when applied to clinical samples, and was successfully cross-validated with a conventional off-line SPE, LC-MS/MS method.

Determination of MK-0767 enantiomers in human plasma by normal phase LC-MS/MS.

A sensitive and selective analytical method for the enantioselective determination of MK-0767, a dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist, in human plasma has been developed and validated. The chromatography is based on normal-phase chiral separation on a Kromasil, 5 microm, CHI-DMB 250 mm x 4.6 mm column. The detection involves the direct introduction of the normal phase eluent into MS/MS without the addition of a post-column reagent. Atmospheric pressure chemical ionization (APcI) mode was selected as the ion source in this method. With proper sample handling and processing procedures, ex vivo interconversion of the enantiomers was kept to minimum during sample collection, preparation and short term storage of frozen human plasma samples. The method was successfully utilized to determine the concentrations of MK-0767 enantiomers in human plasma to support pharmacokinetic investigation in man.

Simultaneous determination of a novel M3 muscarinic receptor antagonist and its active 5-OH metabolite in human plasma using liquid chromatography/tandem mass spectrometry.

A sensitive, specific, and robust liquid chromatography (LC)/mass spectrometry (MS)/MS method has been developed and validated for a novel M(3) muscarinic receptor antagonist (I) and its active 5-OH metabolite (II) in human plasma. The assay involves a two-step liquid-liquid extraction of the compounds from human plasma, high performance liquid chromatography (HPLC) separation, and MS/MS for the detection of the analytes. The method provides a linear response from a quantitation limit of 0.05-20 ng/ml for I and 0.1-20 ng/ml for II using 1 ml of plasma. The mean absolute recovery was 85.4% for I and 80.8% for II, respectively. The intra-assay accuracy of I and II averaged from 95.0 to 105.3% with coefficient of variation (CV) values

Absorption, metabolism, and excretion of [14C]MK-0767 (2-methoxy-5-(2,4-dioxo-5-thiazolidinyl)-N-[[4-(trifluoromethyl)phenyl] methyl]benzamide) in humans.

MK-0767 (KRP-297; 2-methoxy-5-(2,4-dioxo-5-thiazolidinyl)-N-[[4-(trifluoromethyl)phenyl] methyl]benzamide) is a thiazolidinedione (TZD)-containing dual agonist of the peroxisome proliferator-activated receptors alpha and gamma that has been studied as a potential treatment for patients with type 2 diabetes. The metabolism and excretion of [14C]MK-0767 were evaluated in six human volunteers after a 5-mg (200 microCi) oral dose. Excretion of 14C radioactivity was found to be nearly equal into the urine (approximately 50%) and feces (approximately 40%). Elimination of [14C]MK-0767 was primarily by metabolism, with minimal excretion of parent compound into the urine (<0.5% of dose) and feces (approximately 14% of the dose). [14C]MK-0767 was the major circulating compound-related entity (>96% of radioactivity) through 48 h postdose. It was also found that approximately 91% of the total radioactivity area under the curve was due to intact MK-0767. Several minor metabolites were detected in plasma (<1% of radioactivity, each), formed by cleavage of the TZD ring and subsequent S-methylation and oxidation. All the metabolites excreted into urine were formed by TZD cleavage, whereas the major metabolite in feces was the O-demethylated derivative of MK-0767.