Bioequivalence of sitagliptin/metformin fixed-dose combination tablets and concomitant administration of sitagliptin and metformin in healthy adult subjects: a randomized, open-label, crossover study.

BACKGROUND: Treatment with an oral antihyperglycaemic agent administered as monotherapy is often unsuccessful at achieving or maintaining glycaemic control in patients with type 2 diabetes mellitus. The combined use of sitagliptin and metformin is an effective treatment for type 2 diabetes mellitus, consistent with the complementary mechanisms of action by which these two agents improve glucose control. OBJECTIVES: To establish bioequivalence between sitagliptin/metformin fixed-dose combination (FDC) tablets (Janumet®) and co-administration of corresponding doses of sitagliptin and metformin as individual tablets. METHODS: This was an randomized, open-label, two-part, two-period crossover study, which included a total of 48 healthy subjects, 24 subjects per part (parts I and II). Within each part, subjects were assigned to receive treatments in random order; treatment periods were separated by a washout interval of at least 7 days. Eligible study participants included healthy, non-smoking (within previous 6 months), male and female subjects aged between 18 and 45 years with a body mass index ≤32 kg/m². Part I consisted of treatments A (co-administration of sitagliptin 50 mg and metformin 500 mg) and B (sitagliptin/metformin 50 mg/500 mg FDC tablet); part II consisted of treatments C (co-administration of sitagliptin 50 mg and metformin 1000 mg) and D (sitagliptin 50 mg/metformin 1000 mg FDC tablet). Blood samples were collected pre-dose and up to 72 hours post-dose in each treatment period for determination of plasma sitagliptin and metformin concentrations and calculation of the respective pharmacokinetic parameters. The area under the plasma concentration-time curve from time zero to infinity (AUC(∞)) and the maximum plasma concentration (C(max)) for both sitagliptin and metformin were designated as the primary and secondary study endpoints, respectively, and analysed using an ANOVA model after logarithmic transformation of the data. Bioequivalence was established if the 90% confidence intervals (CIs) for the geometric mean ratios (GMRs; FDC tablet/co-administration) of the AUC(∞) and C(max) for both sitagliptin and metformin fell within pre-specified bounds of (0.80, 1.25). RESULTS: The GMRs (90% CI) for the AUC(∞) of sitagliptin 50 mg and metformin 500 mg were 0.98 (0.96, 1.00) and 1.0 (0.95, 1.04), respectively, and for C(max) of sitagliptin and metformin were 1.00 (0.94, 1.06) and 1.00 (0.94, 1.06), respectively. The GMRs (90% CI) for the AUC(∞) of sitagliptin 50 mg and metformin 1000 mg (part II) were 0.97 (0.95, 0.99) and 1.00 (0.94, 1.07), respectively, and for the C(max) of sitagliptin and metformin were 0.94 (0.88, 1.01) and 1.01 (0.93, 1.10), respectively. In both part I and part II, the 90% CIs of the GMRs of the AUC(∞) and C(max) for both sitagliptin and metformin all fell within the pre-specified bioequivalence bounds of (0.80, 1.25). Administration of single doses of sitagliptin/metformin 50 mg/500 mg (part I) and 50 mg/1000 mg FDC tablets (part II) and co-administration of corresponding doses of sitagliptin and metformin as individual tablets were generally well tolerated. CONCLUSION: The sitagliptin/metformin 50 mg/500 mg and 50 mg/1000 mg FDC tablets are bioequivalent to co-administration of corresponding doses of sitagliptin and metformin as individual tablets and support bioequivalence to the sitagliptin/metformin 50 mg/850 mg tablet strength. These results indicate that the safety and efficacy profile of co-administration of sitagliptin and metformin can be extended to the sitagliptin/metformin FDC tablets.

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.

The effects of modifying in vivo cytochrome P450 3A (CYP3A) activity on etoricoxib pharmacokinetics and of etoricoxib administration on CYP3A activity.

To investigate the influence of modifying in vivo cytochrome P450 3A (CYP3A) activity on the pharmacokinetics of etoricoxib, a selective inhibitor of cyclooxygenase-2, and of etoricoxib administration on CYP3A activity, a 3-part, randomized, crossover study was conducted in 3 panels of healthy volunteers. In part I, 8 subjects were administered a single dose of 60 mg etoricoxib alone and following daily doses of 400 mg ketoconazole, a known strong inhibitor of CYP3A. In part II, 8 different subjects were administered a single dose of 60 mg etoricoxib alone and following daily doses of 600 mg rifampin, a known strong inducer of CYP3A. In parts I and II, plasma samples were collected following each etoricoxib dose and analyzed for etoricoxib. In part III, 8 different subjects were administered 120 mg etoricoxib or placebo once daily for 11 days, and the erythromycin breath test was administered on day 11 of each period. Coadministration of etoricoxib with daily doses of ketoconazole resulted in an average 43% increase in etoricoxib AUC; based on previous studies, this increase would not be expected to have any clinically meaningful effect. In contrast, coadministration of etoricoxib with daily doses of rifampin had a potentially clinically important effect on etoricoxib pharmacokinetics (average 65% decrease in etoricoxib AUC). Etoricoxib had no effect on hepatic CYP3A activity, as assessed by the erythromycin breath test.