Effects of Suvorexant, an Orexin Receptor Antagonist, on Respiration during Sleep In Patients with Obstructive Sleep Apnea.

STUDY OBJECTIVES: To investigate the respiratory effects of suvorexant, an orexin receptor antagonist for treating insomnia, in patients with obstructive sleep apnea (OSA). METHODS: This was a randomized, double-blind, placebo-controlled, 2-period (4 days per period), crossover, sleep laboratory study. Twenty-six patients aged 18-65 years with mild (apnea-hypopnea index [AHI] ≥ 5 and < 15) to moderate (AHI ≥ 15 and < 30) OSA were randomized to receive suvorexant 40 mg or placebo in period-1 and then crossed over to the other treatment in period-2. Breathing during sleep was measured by AHI (primary endpoint) and oxygen saturation assessed by pulse oximetry (SpO2, secondary endpoint). The study was powered to rule out a mean increase in AHI between suvorexant and placebo of 5 or greater on Day 4. RESULTS: There was a small increase in mean AHI (2.66) in OSA patients after multiple doses of suvorexant relative to placebo, with the upper 90% CI bound slightly exceeding 5.00 (0.22, 5.09). No increase in mean AHI was observed after a single dose of suvorexant versus placebo (mean difference = -0.47 [-3.20, 2.26]), and there was no treatment effect on mean SpO2 during total sleep time after single or multiple doses (Day 1: mean difference = -0.04 [-0.49, 0.42]; Day 4: mean difference = -0.06 [-0.45, 0.33]). There was inter- and intra-individual variability in suvorexant respiratory effects. CONCLUSIONS: Suvorexant 40 mg, twice the 20 mg maximum recommended dose for treating insomnia in the USA and Japan, does not appear to have clinically important respiratory effects during sleep in patients with mild to moderate OSA as assessed by mean AHI and SpO2. Due to inter- and intra-individual variability in respiratory effects, suvorexant should be used with caution in patients with compromised respiratory function, and at the lowest effective dose. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov, NCT01300455.

Characterizing the PK/PD relationship for inhibition of capsaicin-induced dermal vasodilatation by MK-3207, an oral calcitonin gene related peptide receptor antagonist.

AIMS: Calcitonin gene related peptide (CGRP) receptor antagonists are effective acute migraine treatments. A capsaicin-induced dermal vasodilatation (CIDV) model has been developed to provide target-engagement information in healthy volunteers. In the model, CGRP release is provoked after dermal capsaicin application, by activating transient receptor potential vanilloid-type-1 (TRPV1) receptors at peripheral sensory nerves. Laser Doppler imaging is used to quantify CIDV and subsequent inhibition by CGRP receptor antagonists. We sought to evaluate a CGRP receptor antagonist, MK-3207, in the biomarker model and to assess the predictability of the CIDV response to migraine clinical efficacy. METHODS: An integrated population pharmacokinetic/pharmacodynamic (PK/PD) model was developed to describe the exposure-response relationship for CIDV inhibition by CGRP and TRPV1 receptor antagonists. MK-3207 dose-response predictions were made based on estimated potency from the PK/PD model and mean plasma concentrations observed at the doses investigated. RESULTS: The results suggested that a 20 mg dose of MK-3207 (EC50 of 1.59 nm) would be required to attain the peripheral CIDV response at a target level that was shown previously to correlate with 2 h clinical efficacy based on phase 3 telcagepant clinical data, and that a plateau of the dose-response would be reached around 40-100 mg. These predictions provided a quantitative rationale for dose selection in a phase 2 clinical trial of MK-3207 and helped with interpretation of the efficacy results from the trial. CONCLUSIONS: The integrated CIDV PK/PD model provides a useful platform for characterization of PK/PD relationships and predictions of dose-response relationships to aid in future development of CGRP and TRPV1 receptor antagonists.

Influence of laropiprant, a selective prostaglandin D2 receptor 1 antagonist, on the pharmacokinetics and pharmacodynamics of warfarin.

Laropiprant (LRPT), a prostaglandin D2 receptor 1 antagonist shown to reduce niacin-induced flushing symptoms, is being developed in combination with niacin for the treatment of dyslipidemia. This study assessed the pharmacokinetics/pharmacodynamics of single-dose warfarin in the presence/absence of multiple-dose LRPT. Thirteen subjects received 2 treatments in random order separated by > or =10-day washout: (1) multiple-dose LRPT 40 mg/d for 12 days (days -5 to 7) with coadministered single-dose warfarin 30 mg (day 6) and (2) single-dose warfarin 30 mg (day 1). R+- and S(-)-warfarin and international normalized ratio (INR) were assayed predose and up to 168 hours postdose. Comparability was declared if the 90% confidence intervals (CIs) for the geometric mean ratio (GMR; warfarin + LRPT/warfarin alone) of area under the plasma concentration curve from zero to infinity (AUC0-infinity) for R+- and S(-)-warfarin were contained within (0.80, 1.25). The estimated GMRs of AUC0-infinity (90% CIs) were 1.02 (0.96, 1.09) and 1.04 (0.98, 1.09) for R+- and S(-)-warfarin, respectively. The estimated GMRs of maximum plasma concentration (Cmax) (90% CIs) were 1.13 (1.02, 1.26) and 1.11 (0.99, 1.24) for R+- and S(-)-warfarin, respectively. The estimated GMRs of area under the prothrombin time INR curve from 0 to 168 hours on day 21 (INR AUC0-168 h) and average maximum observed prothrombin time INR (INRmax) were 1.02 (0.99, 1.05) and 1.04 (0.98, 1.10), respectively. There was no evidence of clinically meaningful alterations in the pharmacokinetics and pharmacodynamics (ie, INR) of R(+)- or S(-)-warfarin after coadministration of multiple-dose LRPT and single-dose warfarin.

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.