The effects of simvastatin on the pharmacokinectics of sitagliptin.

BACKGROUND: Treatment with the combination of sitagliptin (a dipeptidyl peptidase 4 inhibitor which improves glycemic control) and simvastatin (a well characterized lipid-lowering agent) may be considered an appropriate approach to management of type 2 diabetes and its associated increased risk of cardiovascular disease. OBJECTIVE: An investigation of the effects of simvastatin on the pharmacokinetics of sitagliptin was conducted. METHODS: Ten healthy men and women were enrolled into an open-label, randomized, 2-period, crossover study. Pharmacokinetics of sitagliptin were measured after a single dose of sitagliptin 100-mg alone, and after a single dose of sitagliptin 100-mg administered on Day 5 of a 7 day course of simvastatin 80-mg once daily. RESULTS: The geometric mean ratio of (sitagliptin + simvastatin) / sitagliptin and corresponding 90% confidence interval for sitagliptin AUC0-∞ and Cmax were 1.01 (0.97, 1.05), and 1.12 (1.00, 1.26), respectively. CONCLUSIONS: Simvastatin has no clinically important effect on sitagliptin pharmacokinetics. No dose adjustment for either sitagliptin or simvastatin is recommended when these drugs are coadministered.

Lack of a meaningful effect of anacetrapib on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: • Inhibition of cholesteryl ester transfer protein (CETP) is a potential new mechanism for the treatment of dyslipidaemia. Anacetrapib is a novel CETP inhibitor in development. Warfarin is a commonly prescribed anticoagulant that has a narrow therapeutic index. A drug interaction study for warfarin with a novel CETP inhibitor is expected to be helpful in defining dosing regimens. WHAT THIS STUDY: ADDS • This is the first study to show that there is no clinically meaningful pharmacokinetic interaction between anacetrapib and warfarin. The single dose pharmacokinetics and pharmacodynamics of orally administered warfarin were not meaningfully affected by multiple dose administration of anacetrapib, indicating that anacetrapib does not affect CYP 2C9 clinically. Thus, no dosage adjustment for warfarin is necessary when co-administered with anacetrapib. AIM: Anacetrapib is currently being developed for the treatment of dyslipidaemia. Since warfarin, an anticoagulant with a narrow therapeutic index, is expected to be commonly prescribed in this population, a drug interaction study was conducted. METHODS: In a randomized, open-label, two-period fixed-sequence design, 12 healthy male subjects received two different treatments (treatment A followed by treatment B). In treatment A, a single oral dose of 30 mg warfarin (3 × 10 mg Coumadin(TM) ) was administered on day 1. After a washout interval, subjects began treatment B, where they were given daily 100 mg doses of anacetrapib (1 × 100 mg) beginning on day -14 and continuing through day 7, with concomitant administration of 30 mg warfarin (3 × 10 mg) on day 1. All anacetrapib and warfarin doses were administered with a standard low fat breakfast. After warfarin concentrations and prothrombin time were measured, standard pharmacokinetic, pharmacodynamic and statistical (linear mixed effects model) analyses were applied. RESULTS: Anacetrapib was generally well tolerated when co-administered with warfarin in the healthy males in this study. The geometric mean ratios (GMRs) for warfarin + anacetrapib : warfarin alone and 90% confidence interval (CIs) for warfarin AUC((0-∞)) were 0.94 (0.90, 0.97) for the R(+) warfarin enantiomer and 0.93 (0.87, 0.98) for the S(-) warfarin enantiomer, both being contained in the interval (0.80, 1.25), supporting the primary hypothesis of the study. The GMRs warfarin + anacetrapib : warfarin alone and 90% CIs for the statistical comparison of warfarin C(max) were 1.01 (0.97, 1.05) for both the R(+) warfarin and the S(-) warfarin enantiomers, and were also contained in the interval (0.80, 1.25). The GMR (warfarin + anacetrapib : warfarin alone) and 90% CI for the statistical comparison of INR AUC((0-168 h)) was 0.93 (0.89, 0.96). CONCLUSION: The single dose pharmacokinetics and pharmacodynamics of orally administered warfarin were not meaningfully affected by multiple dose administration of anacetrapib, indicating that anacetrapib does not affect CYP 2C9 clinically. Thus, no dosage adjustment for warfarin is necessary when co-administered with anacetrapib.

A Single-Dose Bioequivalence and Food Effect Study With Aprepitant and Fosaprepitant Dimeglumine in Healthy Young Adult Subjects.

Fosaprepitant dimeglumine, a lyophilized prodrug, is rapidly converted to aprepitant, a substance P/neurokinin 1 (NK1 ) receptor antagonist. Intravenous (IV) fosaprepitant and oral aprepitant are used in combination with other antiemetics to prevent chemotherapy-induced nausea and vomiting. This randomized, phase 1 study was designed to assess the aprepitant area under the curve (AUC0-∞ ) equivalence of a single, oral 165-mg or 185-mg dose of aprepitant to a single 150-mg fosaprepitant IV dose infused over 20 minutes, and to evaluate the effect of food on the bioavailability of the oral 165-mg and 185-mg aprepitant doses. Plasma samples were analyzed for aprepitant, and linear mixed-effects models were applied to natural log-transformed aprepitant AUC data. A 2 one-sided tests procedure was used to evaluate bioequivalence; the adjusted P values for the AUC0-∞ of both oral doses versus the IV dose were < .05, supporting the hypothesis that each single, oral dose of aprepitant is equivalent to the AUC0-∞ of a single IV infusion of fosaprepitant. Food effect results suggest that dose adjustment would not be necessary with a single oral dose of aprepitant. Single-dose administration of oral 165 mg and 185 mg aprepitant and IV 150 mg fosaprepitant was generally well tolerated.

Lack of an effect of anacetrapib on the pharmacokinetics of digoxin in healthy subjects.

Anacetrapib is currently being developed for the oral treatment of dyslipidemia. A clinical study was conducted in healthy subjects to assess the potential for an interaction with orally administered digoxin. Anacetrapib was generally well tolerated when co-administered with digoxin in the healthy subjects in this study. The geometric mean ratios (GMR) for (digoxin + anacetrapib/digoxin alone) and 90% confidence intervals (CIs) for digoxin AUC(0-last) and AUC(0-∞) were 1.05 (0.96, 1.15) and 1.07 (0.98, 1.17), respectively, both being contained in the accepted interval of bioequivalence (0.80, 1.25), the primary hypothesis of the study. The GMR (digoxin + anacetrapib /digoxin alone) and 90% CIs for digoxin C(max) were 1.23 (1.14, 1.32). Median T(max) and mean apparent terminal t(½) of digoxin were comparable between the two treatments. The single-dose pharmacokinetics of orally administered digoxin were not meaningfully affected by multiple-dose administration of anacetrapib, indicating that anacetrapib does not meaningfully inhibit P-glycoprotein. Thus, no dosage adjustment for digoxin is necessary when co-administered with anacetrapib.

Metabolism and excretion of [14C]taranabant, a cannabinoid-1 inverse agonist, in humans.

Taranabant (N-[(1S,2S)-3-(4-chlorophenyl)-2-(3-cyanophenyl)-1-methylpropyl]-2-methyl-2-{[5-(trifluoromethyl)pyridin-2-yl]oxy}propanamide or MK-0364) is an orally active inverse agonist of the cannabinoid 1 (CB-1) receptor that was under development for the management of obesity. The metabolism and excretion of taranabant were investigated following a single oral dose of 5 mg/201 µCi [14C]taranabant to six healthy male subjects. The overall excretion recovery of the administered radioactivity was nearly quantitative (∼92%), with the majority of the dose (∼87%) excreted into faeces and a much smaller fraction (∼5%) into urine. Taranabant was absorbed rapidly, with C(max) of radioactivity attained at 1-2-h postdose. The parent compound and its monohydroxylated metabolite, M1, were the major radioactive components circulating in plasma and comprised ∼12-24% and 33-42%, respectively, of the plasma radioactivity for up to 48 h. A second monohydroxylated metabolite, designated as M1a, represented ∼10-12% of the radioactivity in the 2- and 8-h postdose plasma profiles. Metabolite profiles of the faeces samples consisted mainly of the (unabsorbed) parent compound and multiple diastereomeric carboxylic acid derivatives derived from oxidation of the geminal methyl group of the parent compound and of the hydroxylated metabolite/s. These data suggest that, similar to rats and monkeys, taranabant is primarily eliminated in humans via oxidative metabolism and excretion of metabolites via the biliary/faecal route.

Pharmacokinetics, safety, and tolerability of phentermine in healthy participants receiving taranabant, a novel cannabinoid-1 receptor (CB1R) inverse agonist.

This study assessed the potential pharmacokinetic interaction and safety/tolerability of taranabant and phentermine coadministration. This was a randomized, double-blind, 3-panel, fixed-sequence study in healthy participants. Panels A, B, and C evaluated the safety/tolerability of phentermine 15 mg coadministered with taranabant 0.5, 1, and 2 mg for 7 days (panel A) and 28 days (panels B and C). In panels A and C, phentermine 15 mg was administered both with (7 days, panel A; 28 days, panel C) and without (7 days) taranabant 0.5 mg or 2 mg to evaluate pharmacokinetics. The primary endpoint was phentermine AUC(0-24 h) in panels A and C. Secondary endpoints were changes from baseline in blood pressure and heart rate for all panels. The geometric mean ratios and 90% confidence intervals for phentermine AUC(0-24 h) in the presence/absence of taranabant 0.5 mg and 2 mg were 1.08 (0.99, 1.17) and 1.04 (0.98, 1.10), respectively. No significant differences in blood pressure and heart rate were observed with any treatment versus placebo. Coadministration of taranabant 0.5 mg, 1 mg, and 2 mg with phentermine was well tolerated with no pharmacokinetic interaction and did not result in meaningful changes in blood pressure or heart rate versus placebo.

Pharmacokinetics of digoxin in healthy subjects receiving taranabant, a novel cannabinoid-1 receptor inverse agonist.

INTRODUCTION: Interaction studies with digoxin (Lanoxin; GlaxoSmithKline, Research Triangle Park, NC, USA), a commonly prescribed cardiac glycoside with a narrow therapeutic index and a long half-life, are typically required during the development of a new drug, particularly when it is likely that digoxin may be given to patients also treated with the new agent, taranabant--a cannabinoid-1 receptor inverse agonist--for weight loss. This study was designed to establish if this combination of therapy has the potential of a significant pharmacokinetic interaction. METHODS: This open-label, fixed-sequence, two-period study investigated whether taranabant, administered to steady state, affects the well-described single-dose pharmacokinetics of digoxin. During the first period, 12 healthy men and women ranging in age from 21 to 35 years received a single oral dose of digoxin 0.5 mg. Following a 10-day wash out, they started a 19-day taranabant dosing regimen (6 mg once daily from day -14 to day 5) designed to establish and maintain steady-state levels of taranabant. On study day 1, subjects received a single oral dose of digoxin 0.5 mg. The plasma levels of digoxin were followed for an additional 4 days while the dosing of taranabant continued. RESULTS: The geometric mean ratio and 90% confidence intervals for digoxin AUC(0-infinity) were 0.91 (0.83, 0.99), falling within the prespecified comparability intervals (CI) of (0.8, 1.25), which is within the usually allowed interval for bioequivalence. The geometric mean ratio and 90% CI for digoxin maximum plasma concentration (C(max)) were 1.23 (1.09, 1.40). The median time to C(max) was the same for both treatments. CONCLUSION: Multiple doses of 6 mg taranabant do not have a clinically meaningful effect on the pharmacokinetics of a single oral dose of digoxin.

Influence of taranabant, an orally active, highly selective, potent cannabinoid-1 receptor (CB1R) inverse agonist, on ethinyl estradiol and norelgestromin plasma pharmacokinetics.

Taranabant, an orally active, potent, and highly selective CB-1 receptor inverse agonist, is being developed for the treatment of obesity. This randomized, placebo-controlled, multiple-dose, crossover study evaluated the effect of taranabant on the pharmacokinetics of ethinyl estradiol and norelgestromin in healthy women receiving > or =3 months of therapy with oral contraceptives. Nineteen participants with normal menstrual cycles received oral contraceptives on days 1 to 21 during 2 consecutive contraceptive cycles. Participants received taranabant 6 mg/day or placebo on days 1 to 21 of each contraceptive cycle. Plasma samples were collected predose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 hours postdose on day 21 of each cycle for determination of AUC0-24 h and Cmax of ethinyl estradiol and norelgestromin. Lack of a clinically important effect was declared if the 90% confidence intervals for the geometric mean ratio of AUC0-24 h and Cmax in the absence and presence of taranabant were contained within the predefined bounds of (0.8, 1.25). The geometric mean ratios and 90% confidence intervals of ethinyl estradiol and norelgestromin, respectively, were 0.93 (0.87, 1.00) and 1.02 (0.96, 1.09) for AUC0-24 h and 0.95 (0.88, 1.01) and 0.95 (0.88, 1.01) for Cmax. In summary, coadministration of multiple-dose taranabant 6 mg with oral contraceptives did not lead to clinically meaningful alterations in the pharmacokinetic profiles of ethinyl estradiol or norelgestromin.

Influence of taranabant, a cannabinoid-1 receptor inverse agonist, on pharmacokinetics and pharmacodynamics of warfarin.

INTRODUCTION: The pharmacokinetic/pharmacodynamic effects of warfarin were assessed in the presence and absence of taranabant, an orally active, highly selective, potent, cannabinoid-1 receptor inverse agonist, which was being developed for the treatment of obesity. METHODS: Twelve subjects were assigned to two open-label treatments in fixed sequence separated by a 14-day washout. Treatment A was single-dose warfarin 30 mg on day 1. Treatment B was multiple-dose taranabant 6 mg each day for 21 days (days -14 to day 7) with coadministration of singledose warfarin 30 mg on day 1. Blood samples were collected predose and up to 168 hours postdose for assay of R(+)-and S(-)-warfarin and prothrombin time/international normalized ratio (PT/INR). RESULTS: The geometric mean ratios (GMR; warfarin+taranabant/warfarin 90% confidence interval [CI] primary endpoints) for area under the curve (AUC)(0-infinity) for R(+)-and S(-)-warfarin were 1.10 (90% CI: 1.03, 1.18) and 1.06 (90% CI: 1.00, 1.13), respectively. The GMRs (warfarin+taranabant/warfarin) for the maximum plasma concentration (C(max)) of S(-)-and R(+)-warfarin were 1.16 (90% CI: 1.05, 1.28) and 1.17 (90% CI: 1.07, 1.29), respectively. For R(+)-and S(-)-warfarin, the 90% CIs for AUC(0-infinity) GMRs fell within the prespecified bounds. Taranabant did not produce a clinically meaningful effect on PT/INR. CONCLUSION: No clinically significant alterations of the pharmacokinetics of R(+)-and S(-)-warfarin were seen following coadministration of multipledose taranabant 6 mg and single-dose warfarin 30 mg.

Multiple-dose pharmacokinetics, pharmacodynamics, and safety of taranabant, a novel selective cannabinoid-1 receptor inverse agonist, in healthy male volunteers.

Taranabant is a cannabinoid-1 receptor inverse agonist for the treatment of obesity. This study evaluated the safety, pharmacokinetics, and pharmacodynamics of taranabant (5, 7.5, 10, or 25 mg once daily for 14 days) in 60 healthy male subjects. Taranabant was rapidly absorbed, with a median t(max) of 1.0 to 2.0 hours and a t(1/2) of approximately 74 to 104 hours. Moderate accumulation was observed in C(max) (1.18- to 1.40-fold) and AUC(0-24 h) (1.5- to 1.8-fold) over 14 days for the 5-, 7.5-, and 10-mg doses, with an accumulation half-life ranging from 15 to 21 hours. Steady state was reached after 13 days. After multiple-dose administration, plasma AUC(0-24 h) and C(max) of taranabant increased dose proportionally (5-10 mg) and increased somewhat less than dose proportionally for 25 mg. Taranabant was generally well tolerated up to doses of 10 mg and exhibited multiple-dose pharmacokinetics consistent with once-daily dosing.

Safety, tolerability, pharmacokinetics, and pharmacodynamic properties of taranabant, a novel selective cannabinoid-1 receptor inverse agonist, for the treatment of obesity: results from a double-blind, placebo-controlled, single oral dose study in healthy volunteers.

Taranabant is a novel cannabinoid CB-1 receptor (CB1R) inverse agonist in clinical development for the treatment of obesity. This double-blind, randomized, placebo-controlled, single oral dose study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of taranabant (0.5-600 mg) in 24 healthy male volunteers. Single-dose AUC(0-infinity) and C(max) values for taranabant increased approximately linearly with dose up to 200 mg, with slightly less than dose-proportional increases in AUC(0-infinity) and C(max) values for doses >200 mg. Plasma taranabant had a biphasic disposition, with a median t(max) of 1 to 2.5 hours and a terminal elimination t((1/2)) of 38 to 69 hours. Coadministration of taranabant with a high-fat meal led to a 14% increase in C(max) and a 74% increase in AUC(0-infinity). Clinical adverse experiences associated with single doses of taranabant were generally mild and transient. Of the 198 clinical adverse experiences reported, the most common drug-related ones were nausea (36), headache (22), drowsiness (14), abdominal discomfort/abdominal pain/stomachache (14), hiccups (9), dizziness (8), decreased appetite (7), increased bowel movement (7), mood change (6), tiredness (4), vomiting (4), and sweating increased (4). Taranabant has pharmacokinetic characteristics suitable for a once-daily dosing regimen.

Aprepitant when added to a standard antiemetic regimen consisting of ondansetron and dexamethasone does not affect vinorelbine pharmacokinetics in cancer patients.

PURPOSE: Aprepitant, a selective neurokinin-1 (NK-1) receptor antagonist approved for the treatment and prevention of emesis caused by moderately and highly emetogenic chemotherapy, is an inhibitor, inducer, and substrate of the cytochrome P450 3194 pathway. The CYP3A4 pathway is the major pathway of the metabolism of vinorelbine, a vinca alkaloid frequently used in combination with cisplatin. Therefore, we studied the potential interaction of the aprepitant 3-day antiemetic regimen on the pharmacokinetics of vinorelbine. PATIENTS AND METHODS: Fourteen patients with metastatic solid tumors were included in this open-label, balanced, 2-period crossover study. In treatment arm A, vinorelbine (25 mg/m2 weekly) was administered alone, while in treatment arm B the same dose of vinorelbine was administered following the administration of the aprepitant antiemetic regimen on day 1 and alone on day 8. The antiemetic regimen of aprepitant was comprised of the following; on day 1: 125 mg aprepitant, 12 mg dexamethasone, and 32 mg ondansetron; on days 2 and 3: 80 mg aprepitant and 8 mg dexamethasone and on day 4: 8 mg dexamethasone. Blood samples for vinorelbine pharmacokinetic analysis were collected over 96 h. RESULTS: Two patients discontinued the study due to adverse events that were judged not to be drug-related. Complete pharmacokinetic data of vinorelbine administered alone and with the aprepitant antiemetic regimen were obtained in 12 patients. The mean plasma concentration profile of vinorelbine administered with aprepitant was identical to that following vinorelbine administered alone, with geometric mean vinorelbine plasma AUC ratios of treatment B day 1/treatment A day 1 and of treatment B day 8/treatment A day of 1.01 (0.93, 1.10) and 1.00 (0.92, 1.08), respectively. CONCLUSION: As the aprepitant antiemetic regimen has no detectable inhibitory or inductive effect on the pharmacokinetics of vinorelbine, aprepitant when added to a standard antiemetic regimen consisting of ondansetron and dexamethasone can be safely combined with vinorelbine at clinically recommended doses.

Lack of effect of aprepitant on hydrodolasetron pharmacokinetics in CYP2D6 extensive and poor metabolizers.

To prevent chemotherapy-induced nausea and vomiting, aprepitant is given with a corticosteroid and a 5-hydroxytryptamine type 3 antagonist, such as dolasetron. Dolasetron is converted to the active metabolite hydrodolasetron, which is cleared largely via CYP2D6. The authors determined whether aprepitant, a moderate CYP3A4 inhibitor, alters hydrodolasetron pharmacokinetics in CYP2D6 poor and extensive metabolizers. Six CYP2D6 poor and 6 extensive metabolizers were randomized in an open-label, crossover fashion to treatment A (dolasetron 100 mg on day 1) and treatment B (dolasetron 100 mg plus aprepitant 125 mg on day 1, aprepitant 80 mg on days 2-3). For hydrodolasetron area under the concentration-versus-time curve (AUC0-infinity) and peak plasma concentration (Cmax), geometric mean ratios (B/A) and 90% confidence intervals (CIs) fell below the predefined limit (2.0) for clinical significance (AUC0-infinity, 1.09 [90% CI, 1.01-1.18], Cmax, 1.08 [90% CI, 0.94-1.24]). Aprepitant did not affect the pharmacokinetics of hydrodolasetron, regardless of CYP2D6 metabolizer type, and was generally well tolerated when coadministered with dolasetron in volunteers.