Pharmacokinetic and Safety Profile of the Novel HIV Nonnucleoside Reverse Transcriptase Inhibitor MK-8507 in Adults without HIV.

MK-8507 is a novel HIV-1 nonnucleoside reverse transcriptase inhibitor in clinical development with potential for once-weekly oral administration for the treatment of HIV-1 infection. Two randomized, double-blind, placebo-controlled phase 1 studies in adults without HIV-1 evaluated the safety, tolerability, and pharmacokinetics of single and multiple doses of MK-8507; drug interaction with midazolam (a cytochrome P450 3A4 substrate) and food effect were also assessed. In study 1, 16 participants received oral ascending single doses of MK-8507 (2 to 400 mg) or placebo in an alternating fashion. In study 2, 24 participants received ascending single doses of MK-8507 (400 to 1,200 mg) or placebo and multiple doses (once weekly for 3 weeks) of MK-8507 (100 to 400 mg) or placebo. MK-8507 pharmacokinetics were approximately dose proportional at 2 to 1,200 mg. MK-8507 had a time to maximum concentration of 2 to 7 h and a mean terminal half-life of ∼58 to 84 h. MK-8507 doses of ≥100 mg achieved a plasma concentration at 168 h postdose (7 days) associated with antiviral efficacy. A high-fat meal had no clinically meaningful effect on MK-8507 pharmacokinetics, and MK-8507 400 mg once weekly had no clinically meaningful effect on midazolam pharmacokinetics. Single and multiple doses of MK-8507 were generally well tolerated. No trends with dose and no clinically meaningful changes were observed in vital signs, electrocardiograms, and laboratory safety tests. The pharmacokinetics and safety data are supportive of once-weekly oral administration and support further clinical investigation of MK-8507 for the treatment of HIV-1 infection.

Single Oral Doses of MK-8507, a Novel Non-Nucleoside Reverse Transcriptase Inhibitor, Suppress HIV-1 RNA for a Week.

BACKGROUND: MK-8507 is a novel HIV-1 non-nucleoside reverse transcriptase inhibitor being developed for treatment of HIV-1 infection. MK-8507 has high antiviral potency in vitro and pharmacokinetic (PK) properties that support once-weekly dosing. SETTING: A phase 1, open-label, proof-of-concept study was conducted in treatment-naive adults with HIV-1 infection to assess monotherapy antiviral activity. METHODS: In 3 sequential panels, participants aged 18-60 years with baseline plasma HIV-1 RNA ≥10,000 copies/mL and CD4+ T-cell count >200/mm3 received a single oral dose of 40, 80, or 600 mg MK-8507 in the fasted state. Participants were assessed for HIV-1 RNA for at least 7 days, PKs for 14 days, and safety and tolerability for 21 days postdose. RESULTS: A total of 18 participants were enrolled (6 per panel). The mean 7-day postdose HIV-1 RNA reduction ranged from ∼1.2 to ∼1.5 log10 copies/mL across the doses assessed. One patient had a viral rebound associated with emergence of an F227C reverse transcriptase variant (per chain-termination method sequencing) 14 days postdose; this variant was found in a second participant by ultra-deep sequencing as an emerging minority variant. MK-8507 PKs were generally dose-proportional and similar to observations in participants without HIV-1 infection in prior studies; mean MK-8507 half life was 56-69 hours in this study. MK-8507 was generally well tolerated at all doses. CONCLUSIONS: The robust antiviral activity, PK, and tolerability of MK-8507 support its continued development as part of a complete once weekly oral regimen for HIV-1 treatment; combination therapy could mitigate the emergence of resistance-associated variants.

Thorough QTc Study of a Single Supratherapeutic Dose of Relebactam in Healthy Participants.

The effects of supratherapeutic doses of intravenous (IV) relebactam on duration of ventricular depolarization and subsequent repolarization were assessed in a thorough QT/corrected QT study. This was a single-dose, double-blind (relebactam only), randomized, placebo- and positive-controlled, 3-period, balanced crossover study in healthy participants. Participants received in randomized order, and separated by a washout (≥4 days), a single dose of IV relebactam 1150 mg, oral moxifloxacin 400 mg (open-label positive control), and IV placebo. Least squares mean and 2-sided 90% confidence interval for change from baseline in population-derived corrected QT intervals for relebactam, moxifloxacin, and placebo were estimated for 24 hours. The upper limit of the 90% confidence interval of all least squares mean population-derived corrected QT treatment differences from placebo was not >10 milliseconds at any time point for 24 hours. Corrected QT assay sensitivity was confirmed with moxifloxacin treatment. Analysis of electrocardiogram parameters resulted in no additional cardiac safety concerns. Overall, a supratherapeutic dose of relebactam yielded no cardiac safety events; the 1150-mg supratherapeutic dose (4.6-fold above the 250-mg therapeutic dose) was not associated with QT prolongation or other abnormal cardiodynamic parameters. This study lends additional support to relebactam's use as a ß-lactamase inhibitor in antimicrobial therapy.

Lack of a clinically important effect of moderate hepatic insufficiency and severe renal insufficiency on raltegravir pharmacokinetics.

Raltegravir is a human immunodeficiency virus type 1 integrase strand transfer inhibitor with potent activity in vitro and in vivo. Raltegravir is primarily cleared by hepatic metabolism via glucuronidation (via UDP glucuronosyltransferase 1A1), with a minor component of elimination occurring via the renal pathway. Since the potential exists for raltegravir to be administered to patients with hepatic or renal insufficiency, two studies were conducted to evaluate the influence of moderate hepatic insufficiency (assessed by using the Child-Pugh criteria) and severe renal insufficiency (creatinine clearance, <30 ml/min/1.73 m(2)) on the pharmacokinetics of raltegravir. Study I evaluated the pharmacokinetics of 400 mg raltegravir in eight patients with moderate hepatic insufficiency and eight healthy, matched control subjects. Study II evaluated the pharmacokinetics of 400 mg raltegravir in 10 patients with severe renal insufficiency and 10 healthy, matched control subjects. All participants received a single 400-mg dose of raltegravir in the fasted state. In study I, the geometric mean ratios (GMR; mean value for the group with moderate hepatic insufficiency/mean value for the healthy controls) and 90% confidence intervals (CIs) for the area under the concentration-time curve from time zero to infinity (AUC(0-infinity)), the maximum concentration of drug in plasma (C(max)), and the concentration at 12 h (C(12)) were 0.86 (90% CI, 0.41, 1.77), 0.63 (90% CI, 0.23, 1.70), and 1.26 (90% CI, 0.65, 2.43), respectively. In study II, the GMRs (mean value for the group with renal insufficiency/mean value for the healthy controls) and 90% CIs for AUC(0-infinity), C(max), and C(12) were 0.85 (90% CI, 0.49, 1.49), 0.68 (90% CI, 0.35, 1.32), and 1.28 (90% CI, 0.79, 2.06), respectively. Raltegravir was generally well tolerated by patients with moderate hepatic or severe renal insufficiency, and there was no clinically important effect of moderate hepatic or severe renal insufficiency on the pharmacokinetics of raltegravir. No adjustment in the dose of raltegravir is required for patients with mild or moderate hepatic or renal insufficiency.

Lack of a significant drug interaction between raltegravir and tenofovir.

Raltegravir is a novel human immunodeficiency virus type 1 (HIV-1) integrase inhibitor with potent in vitro activity (95% inhibitory concentration of 31 nM in 50% human serum). This article reports the results of an open-label, sequential, three-period study of healthy subjects. Period 1 involved raltegravir at 400 mg twice daily for 4 days, period 2 involved tenofovir disoproxil fumarate (TDF) at 300 mg once daily for 7 days, and period 3 involved raltegravir at 400 mg twice daily plus TDF at 300 mg once daily for 4 days. Pharmacokinetic profiles were also determined in HIV-1-infected patients dosed with raltegravir monotherapy versus raltegravir in combination with TDF and lamivudine. There was no clinically significant effect of TDF on raltegravir. The raltegravir area under the concentration time curve from 0 to 12 h (AUC(0-12)) and peak plasma drug concentration (C(max)) were modestly increased in healthy subjects (geometric mean ratios [GMRs], 1.49 and 1.64, respectively). There was no substantial effect of TDF on raltegravir concentration at 12 h postdose (C(12)) in healthy subjects (GMR [TDF plus raltegravir-raltegravir alone], 1.03; 90% confidence interval [CI], 0.73 to 1.45), while a modest increase (GMR, 1.42; 90% CI, 0.89 to 2.28) was seen in HIV-1-infected patients. Raltegravir had no substantial effect on tenofovir pharmacokinetics: C(24), AUC, and C(max) GMRs were 0.87, 0.90, and 0.77, respectively. Coadministration of raltegravir and TDF does not change the pharmacokinetics of either drug to a clinically meaningful degree. Raltegravir and TDF may be coadministered without dose adjustments.

A study to determine the effects of food and multiple dosing on the pharmacokinetics of vorinostat given orally to patients with advanced cancer.

PURPOSE: This phase I study, conducted in advanced-stage cancer patients, assessed the safety and tolerability of oral vorinostat (suberoylanilide hydroxamic acid), single-dose and multiple-dose pharmacokinetics of vorinostat, and the effect of a high-fat meal on vorinostat pharmacokinetics. EXPERIMENTAL DESIGN: Patients (n = 23) received single doses of 400 mg vorinostat on day 1 (fasted) and day 5 (fed) with 48 hours of pharmacokinetic sampling on both days. Patients received 400 mg vorinostat once daily on days 7 to 28. On day 28, vorinostat was given (fed) with pharmacokinetic sampling for 24 hours after dose. RESULTS: The apparent t(1/2) of vorinostat was short (approximately 1.5 hours). A high-fat meal was associated with a small increase in the extent of absorption and a modest decrease in the rate of absorption. A short lag time was observed before detectable levels of vorinostat were observed in the fed state, and T(max) was delayed. Vorinostat concentrations were qualitatively similar following single-dose and multiple-dose administration; the accumulation ratio based on area under the curve was 1.21. The elimination of vorinostat occurred primarily through metabolism, with <1% of the given dose recovered intact in urine. The most common vorinostat-related adverse experiences were mild to moderate nausea, anorexia, fatigue, increased blood creatinine, and vomiting. CONCLUSIONS: Vorinostat concentrations were qualitatively similar after single and multiple doses. A high-fat meal increased the extent and modestly decreased the rate of absorption of vorinostat; this effect is not anticipated to be clinically meaningful. Continued investigation of 400 mg vorinostat given once daily in phase II and III efficacy studies is warranted.

Pharmacokinetic/pharmacodynamic-based decision making in the development of MK-0888, a VEGFR-2/FLT-3 kinase inhibitor.

PURPOSE: MK-0888 is an investigational VEGFR-2 inhibitor with demonstrated potent in vitro enzyme activity. Clinical investigation in healthy volunteers and cancer patients was undertaken to evaluate its pharmacokinetic properties and early safety profile. Early data were used to guide whether further clinical development was warranted. METHODS: Five phase I studies were conducted. Studies 1-4 were conducted in healthy male volunteers and examined safety and pharmacokinetics across a dose range of 0.5-100 mg. Single-dose and limited multiple-dose escalations were performed. Three formulations and food effect were assessed. Study 5 was a dose escalation study in cancer patients, evaluating pharmacokinetics and safety at doses of 6-100 mg administered up to twice daily. RESULTS: Safety: MK-0888 was generally well tolerated in healthy volunteers at single doses up to 100 mg and in cancer patients at doses up to 100 mg twice daily. Pharmacokinetics: After single-dose administration, MK-0888 was readily absorbed with a T(max) of 4-5 h and a half-life of 11.3-22.7 h. AUC, C(max), and C(24h) increased in a slightly less than dose proportional manner. With longer duration multiple-dose administration (2 weeks), trough concentrations decreased from Day 2 at doses of 50 mg twice daily and higher, suggestive of autoinduction of metabolism. The efficacious trough pharmacokinetic target was not attained at steady state. CONCLUSIONS: The pharmacokinetic behavior of MK-0888 does not support continued development. The early pharmacokinetic profile of the compound provides important information as to the probability of success of MK-0888 achieving efficacious exposures.

Clinical pharmacology profile of vorinostat, a histone deacetylase inhibitor.

PURPOSE: Vorinostat is a histone deacetylase inhibitor that has demonstrated preclinical activity in numerous cancer models. Clinical activity has been demonstrated in patients with a variety of malignancies. Vorinostat is presently indicated for the treatment of patients with advanced cutaneous T cell lymphoma (CTCL). Clinical investigation is ongoing for therapy of other solid tumors and hematological malignancies either as monotherapy or in combination with other chemotherapeutic agents. This review summarizes the pharmacokinetic properties of vorinostat. METHODS: Monotherapy pharmacokinetic data across a number of pharmacokinetic studies were reviewed, and data are presented. In addition, literature review was performed to obtain published Phase I and II pharmacokinetic combination therapy data to identify and characterize potential drug interactions with vorinostat. Pharmacokinetic data in special populations were also reviewed. RESULTS: The clinical pharmacology profile of vorinostat is favorable, exhibiting dose-proportional pharmacokinetics and modest food effect. There appear to be no major differences in the pharmacokinetics of vorinostat in special populations, including varying demographics and hepatic dysfunction. Combination therapy pharmacokinetic data indicate that vorinostat has a low propensity for drug interactions. CONCLUSIONS: Vorinostat's favorable clinical pharmacology and drug interaction profile aid in the ease of administration of vorinostat for the treatment of advanced CTCL and will be beneficial in continued assessment for other oncologic indications. Although a number of studies have been conducted to elucidate the detailed pharmacokinetic profile of vorinostat, more rigorous assessment of vorinostat pharmacokinetics, including clinical drug interaction studies, will be informative.

Effect of different durations and formulations of diltiazem on the single-dose pharmacokinetics of midazolam: how long do we go?

Understanding how inhibition of cytochrome P4503A (CYP3A) affects the metabolism of a new drug is critical in determining if a clinically relevant drug interaction will occur. Diltiazem interaction studies assess a given compound's sensitivity to moderate CYP3A inhibition. The present study compared the effect different durations and formulations of diltiazem (extended release [XR] and conventional release [CR]) had on the single-dose pharmacokinetics of midazolam. The geometric mean ratio (GMR; midazolam + diltiazem(XR × 5 days)/midazolam + diltiazem(XR × 2 days)) for midazolam AUC(0-∞) was 0.98 (90% confidence interval [CI], 0.87, 1.10). The GMR (midazolam + diltiazem(XR × 2 days)/midazolam + diltiazem(CR × 2 days)) for midazolam AUC(0-∞) was 0.82 (90% CI, 0.73, 0.92). Simcyp simulations accurately predicted the observed clinical results only when a hepatic CYP3A degradation rate (k(deg)) different from that provided by the software was used. The data suggest that dosing diltiazem XR for 2 days predicts the change in midazolam AUC as reliably as 5 days of XR dosing and 2 days of CR dosing. In addition, the authors believe that a hepatic CYP3A kdeg of 0.03 h(-1) should be considered for future Simcyp studies.