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Objective: To assess the antiviral activity, pharmacokinetics, and safety of MK-6186 in HIV-1 non-nucleoside reverse transcriptase inhibitor (NNRTI)-naïve, HIV-1-infected male participants. Design: Double-blind, randomized, two-panel study. Methods: In 2 sequential panels, 18 participants received MK-6186 (40 mg [Panel A] or 150 mg [Panel B]) or matching placebo once daily for 7 days. Plasma samples were collected for measurement of HIV-1 RNA levels and MK-6186 pharmacokinetics. Results: For the mean change from baseline in HIV-1 RNA (log 10 copies/mL) at 24 h post Day 7 dose, the mean difference (90% confidence interval) between MK-6186 and placebo was -1.54 (-1.73, -1.34) in the 40-mg group and -1.28 (-1.81, -0.75) in the 150-mg group. One participant in the 150-mg group had viral rebound at 24 h after Day 6 dosing (Day 7 predose) associated with outgrowth of the V106A minority variant. Ultra-deep sequencing confirmed expansion of this predose minority variant from 0.26% to 63.67%. No outgrowth or rebound was seen in another participant in whom a V106A minority variant was also detected. MK-6186 was generally well tolerated. MK-6186 was rapidly absorbed with peak concentrations at 2 h followed by a biphasic decline. The effective t½ of MK-6186 was 43.9 to 48.7 h. Steady state was not achieved. Conclusions: Daily monotherapy with MK-6186 demonstrated robust antiviral activity with maximal antiviral activity at a dose of 40 mg. One participant in the 150-mg group exhibited viral rebound with outgrowth of the resistant V106A minority variant, demonstrating a risk of resistance development typical of NNRTIs. The reason for this outgrowth remains unclear as no outgrowth occurred in a participant in the 40-mg group in whom the V106A minority variant was also detected. MK-6186 may be an alternative next-generation NNRTI in combination therapy, in that combination antiretroviral therapy could prevent outgrowth of resistant minority variants.

The current standard of care for treating Alzheimer's disease is acetylcholinesterase inhibitors, which nonselectively increase cholinergic signaling by indirectly enhancing activity of nicotinic and muscarinic receptors. These drugs improve cognitive function in patients, but also produce unwanted side effects that limit their efficacy. In an effort to selectively improve cognition and avoid the cholinergic side effects associated with the standard of care, various efforts have been aimed at developing selective M 1 muscarinic receptor activators. In this work, we describe the preclinical and clinical pharmacodynamic effects of the M 1 muscarinic receptor-positive allosteric modulator, MK-7622. MK-7622 attenuated the cognitive-impairing effects of the muscarinic receptor antagonist scopolamine and altered quantitative electroencephalography (qEEG) in both rhesus macaque and human. For both scopolamine reversal and qEEG, the effective exposures were similar between species. However, across species the minimum effective exposures to attenuate the scopolamine impairment were lower than for qEEG. Additionally, there were differences in the spectral power changes produced by MK-7622 in rhesus versus human. In sum, these results are the first to demonstrate translation of preclinical cognition and target modulation to clinical effects in humans for a selective M 1 muscarinic receptor-positive allosteric modulator., (Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.)

The graded glucose infusion (GGI) examines insulin secretory response patterns to continuously escalating glycemia. The current study series sought to more fully appraise its performance characteristics. Key questions addressed were comparison of the GGI to the hyperglycemic clamp (HGC), comparison of insulin secretory response patterns across three volunteer populations known to differ in β-cell function (healthy nonobese, obese nondiabetic, and type 2 diabetic), and characterization of effects of known insulin secretagogues in the context of a GGI. Insulin secretory response was measured as changes in insulin, C-peptide, insulin secretion rates (ISR), and ratio of ISR to prevailing glucose (ISR/G). The GGI correlated well with the HGC (r = 0.72 for ISR/G, P < 0.01). The insulin secretory response in type 2 diabetes (T2DM) was significantly blunted (P < 0.001), whereas it was significantly increased in obese nondiabetics compared with healthy nonobese (P < 0.001). Finally, robust (P < 0.001 over placebo) pharmacological effects were observed in T2DM and healthy nonobese volunteers. Collectively, the findings of this investigational series bolster confidence that the GGI has solid attributes for assessing insulin secretory response to glucose across populations and pharmacology. Notably, the coupling of insulin secretory response to glycemic changes was distinctly and uniformly linear across populations and in the context of insulin secretagogues. (Clinical Trial Registration Nos. NCT00782418, NCT01055340, NCT01373450)., (Copyright © 2016 the American Physiological Society.)

Background: Doravirine is a novel non-nucleoside inhibitor of HIV-1 reverse transcriptase with potent activity against wild-type virus (95% inhibitory concentration 19 nM, 50% human serum). Doravirine has low potential to cause drug-drug interactions since it is primarily eliminated by oxidative metabolism and does not inhibit or significantly induce drug-metabolizing enzymes., Methods: The pharmacokinetics and safety of doravirine were investigated in two double-blind, dose-escalation studies in healthy males. Thirty-two subjects received single doses of doravirine (6-1,200 mg) or matching placebo tablets; 40 subjects received doravirine (30-750 mg) or matching placebo tablets once daily for 10 days. In addition, the effect of doravirine (120 mg for 14 days) on single-dose pharmacokinetics of the CYP3A substrate midazolam was evaluated (10 subjects)., Results: The maximum plasma concentration (Cmax) of doravirine was achieved within 1-5 h with an apparent terminal half-life of 12-21 h. Consistent with single-dose pharmacokinetics, steady state was achieved after approximately 7 days of once daily administration, with accumulation ratios (day 10/day 1) of 1.1-1.5 in the area under the plasma concentration-time curve during the dosing interval (AUC0-24 h), Cmax and trough plasma concentration (C24 h). All dose levels produced C24 h>19 nM. Administration of 50 mg doravirine with a high-fat meal was associated with slight elevations in AUC time zero to infinity (AUC0-∞) and C24 h with no change in Cmax. Midazolam AUC0-∞ was slightly reduced by coadministration of doravirine (geometric mean ratio 0.82, 90% CI 0.70, 0.97). There was no apparent relationship between adverse event frequency or intensity and doravirine dose. No rash or significant central nervous system events other than headache were reported., Conclusions: Doravirine is generally well tolerated in single doses up to 1,200 mg and multiple doses up to 750 mg once daily for up to 10 days, with a pharmacokinetic profile supportive of once-daily dosing. Doravirine at steady state slightly reduced the exposure of coadministered midazolam, to a clinically unimportant extent.

Aims: To characterize pharmacokinetic parameters of MK-0916 and its safety and tolerability in lean, healthy male subjects following single and multiple oral doses. To assess (by stable-isotope labelling) the in vivo inhibition of cortisone-to-cortisol conversion following oral MK-0916., Methods: Data are presented from two randomized, controlled, double-blind, rising-dose phase I studies. In the first study, subjects received single oral doses of 0.4-100 mg MK-0916 (n = 16). In the second study, subjects received 0.2-225 mg MK-0916 followed by daily doses of 0.2-100 mg for 13 days beginning on day 2 or day 15 (n = 80). Plasma and urine drug concentrations were measured for pharmacokinetic analysis. For pharmacodynamic analysis, concentrations of plasma [(13)C4]cortisol were measured by high-pressure liquid chromatography and tandem mass spectrometry following a single oral dose of 5 mg [(13)C4]cortisone., Results: Doses ≥3 mg were rapidly absorbed (time at which maximal concentration was achieved in plasma, 1.1-1.8 h). Exposure (measured as the area under the concentration-time curve from 0 to 168 h) increased approximately in proportion to dose. Values for the maximal plasma concentration and the plasma concentration at 24 h increased in excess of dose proportionality at doses <6 mg and roughly in proportion to dose at doses >6 mg. In subjects dosed with 6 mg MK-0916 once daily for 14 days, the mean trough plasma concentration was 240 nm and in vivo cortisone-to-cortisol conversion was inhibited by 84%. The relationship between plasma MK-0916 and hepatic 11β-hydroxysteroid dehydrogenase type 1 inhibition was well represented by a simple Emax model with an IC50 of 70.4 nm. Exposure to MK-0916 was generally well tolerated., Conclusions: These findings indicate that 11β-hydroxysteroid dehydrogenase type 1 is effectively inhibited in human subjects by doses of MK-0916 that are well tolerated., (© 2013 Merck, Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.,. Whitehouse Station, NJ, USA. British Journal of Clinical Pharmacology © 2013 The British Pharmacological Society.)

Aims: To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of odanacatib (ODN), a cathepsin K inhibitor, in humans., Methods: Two double-blind, randomized, placebo-controlled, single oral dose studies were performed with ODN (2-600 mg) in 44 healthy volunteers (36 men and eight postmenopausal women)., Results: Adverse experiences (AEs) with single doses of ODN were transient and mild to moderate, with the exception of one severe AE of gastroenteritis. Headache was the most frequent AE. After absorption of ODN (initial peak concentrations 4-6 h postdose), plasma concentrations exhibited a monophasic decline, with an apparent terminal half-life of ∼40-80 h. The area under the curve0-24 hours (AUC(0-24 h)), concentration at 24 hours (C(24 h)) and maximum concentration (C(max,overal)) increased in a less than dose-proportional manner from 2 to 600 mg. Administration of ODN with a high-fat meal led to ∼100% increases in AUC(0-24 h), C(max,day1), C(max,overall) and C(24 h) relative to the fasted state, while administration with a low-fat meal led to a ∼30% increase in those parameters. Reduction of biomarkers of bone resorption, the C- and N-telopeptides of cross-links of type I collagen, (CTx and NTx, respectively), was noted at 24 h for doses ≥5 mg and at 168 h postdose for ≥10 mg. In postmenopausal women administered 50 mg ODN, reductions in serum CTx of -66% and urine NTx/creatinine (uNTx/Cr) of -51% relative to placebo were observed at 24 h. At 168 h, reductions in serum CTx (-70%) and uNTx/Cr (-78%) were observed relative to baseline. Pharmacokinetic/pharmacodynamic modeling characterized the ODN concentration/uNTx/Cr relation, with a modeled EC50 value of 43.8 nM and ∼80% maximal reduction., Conclusions: Odanacatib was well tolerated and has a pharmacokinetic and pharmacodynamic profile suitable for once weekly dosing., (© 2012 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Whitehouse Station, NJ, USA. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.)

Cannabinoid 1 receptor (CB1R) inverse agonists are emerging as a potential obesity therapy. However, the physiological mechanisms by which these agents modulate human energy balance are incompletely elucidated. Here, we describe a comprehensive clinical research study of taranabant, a structurally novel acyclic CB1R inverse agonist. Positron emission tomography imaging using the selective CB1R tracer [(18)F]MK-9470 confirmed central nervous system receptor occupancy levels ( approximately 10%-40%) associated with energy balance/weight-loss effects in animals. In a 12-week weight-loss study, taranabant induced statistically significant weight loss compared to placebo in obese subjects over the entire range of evaluated doses (0.5, 2, 4, and 6 mg once per day) (p < 0.001). Taranabant treatment was associated with dose-related increased incidence of clinical adverse events, including mild to moderate gastrointestinal and psychiatric effects. Mechanism-of-action studies suggest that engagement of the CB1R by taranabant leads to weight loss by reducing food intake and increasing energy expenditure and fat oxidation.

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, is an incretin enhancer that is approved for the treatment of type 2 diabetes. Sitagliptin is mainly renally eliminated and not a potent inhibitor of CYP450 enzymes in vitro. Rosiglitazone, a thiazolidenedione, is an insulin sensitizer and mainly metabolized by CYP2C8. Since both agents may potentially be coadministered, the purpose of this study was to examine the effects of sitagliptin on rosiglitazone pharmacokinetics. In this open-label, randomized, 2-period, crossover study, 12 healthy normoglycemic subjects, 21 to 44 years, received single 4-mg doses of rosiglitazone alone in one period and coadministered with sitagliptin on day 5 following a multiple-dose regimen for sitagliptin (200 mg once daily x 5 days) in the other period. The geometric mean ratios and 90% confidence intervals ([rosiglitazone + sitagliptin]/rosiglitazone) for rosiglitazone AUC(0-infinity) and Cmax were 0.98 (0.93, 1.02) and 0.99 (0.88, 1.12), respectively. In conclusion, sitagliptin did not alter the pharmacokinetics of rosiglitazone in healthy subjects.

Context: In response to a meal, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) are released and modulate glycemic control. Normally these incretins are rapidly degraded by dipeptidyl peptidase-4 (DPP-4). DPP-4 inhibitors are a novel class of oral antihyperglycemic agents in development for the treatment of type 2 diabetes. The degree of DPP-4 inhibition and the level of active incretin augmentation required for glucose lowering efficacy after an oral glucose tolerance test (OGTT) were evaluated., Objective: The objective of the study was to examine the pharmacodynamics, pharmacokinetics, and tolerability of sitagliptin., Design: This was a randomized, double-blind, placebo-controlled, three-period, single-dose crossover study., Setting: The study was conducted at six investigational sites., Patients: The study population consisted of 58 patients with type 2 diabetes who were not on antihyperglycemic agents., Interventions: Interventions included sitagliptin 25 mg, sitagliptin 200 mg, or placebo., Main Outcome Measures: Measurements included plasma DPP-4 activity; post-OGTT glucose excursion; active and total incretin GIP levels; insulin, C-peptide, and glucagon concentrations; and sitagliptin pharmacokinetics., Results: Sitagliptin dose-dependently inhibited plasma DPP-4 activity over 24 h, enhanced active GLP-1 and GIP levels, increased insulin/C-peptide, decreased glucagon, and reduced glycemic excursion after OGTTs administered at 2 and 24 h after single oral 25- or 200-mg doses of sitagliptin. Sitagliptin was generally well tolerated, with no hypoglycemic events., Conclusions: In this study in patients with type 2 diabetes, near maximal glucose-lowering efficacy of sitagliptin after single oral doses was associated with inhibition of plasma DPP-4 activity of 80% or greater, corresponding to a plasma sitagliptin concentration of 100 nm or greater, and an augmentation of active GLP-1 and GIP levels of 2-fold or higher after an OGTT.