Pharmacokinetics and antiviral activity of PHX1766, a novel HCV protease inhibitor, using an accelerated Phase I study design.

BACKGROUND: PHX1766 is a novel HCV NS3/4 protease inhibitor with robust potency and high selectivity in replicon studies (50% maximal effective concentration 8 nM). Two clinical trials investigated the safety, tolerability, pharmacokinetics and antiviral activity of PHX1766 in healthy volunteers (HV) and chronic hepatitis C patients, by use of a dose-adaptive overlapping clinical trial design. METHODS: Two randomized, double-blind, placebo-controlled clinical trials were conducted. Single doses of PHX1766 or placebo were administered to 25 HV and six HCV genotype 1-infected patients (50 mg once daily -1,000 mg once daily, 250 mg twice daily and 100 mg of a new formulation of PHX1766 once daily). Multiple doses of PHX1766 or placebo were administered to 32 HV and seven HCV genotype 1-infected patients (50 mg once daily -800 mg twice daily). RESULTS: Oral administration of PHX1766 was safe and well tolerated at all dose levels with rapid absorption (time at which concentration maximum is reached of 1-4 h) and with mean terminal half-lives of 4-23 h. Multiple doses of PHX1766 800 mg twice daily in HCV patients produced an area under the plasma concentration-time curve from time of drug administration to the last time point with a measurable concentration after dosing accumulation ratio of 2.3. The mean maximal observed HCV RNA decline was 0.6 log(10) IU/ml in the first 24 h in the single-dose protocol and 1.5 log(10) IU/ml after 6 days of PHX1766 dosing. CONCLUSIONS: An overlapping, dose-adaptive single-dose and multiple-dose escalating design in HV and HCV-infected patients proved to be highly efficient in identifying a therapeutic dose. Although in vitro replicon studies indicated a robust HCV RNA viral decline of PHX1766, the study in HCV patients demonstrated only modest viral load reduction.

Evaluation of the potential for pharmacokinetic and pharmacodynamic interactions between dutogliptin, a novel DPP4 inhibitor, and metformin, in type 2 diabetic patients.

OBJECTIVE: Dutogliptin is a novel, orally available, potent, and selective DPP4 inhibitor that improves glycemic control in type 2 diabetic patients. The objective of this study was to evaluate the potential pharmacokinetic and pharmacodynamic interactions, as well as the tolerability, of dutogliptin and metformin alone and in combination in type 2 diabetic patients. METHODS: This was a single-center, randomized, open-label, 3-way, crossover study in type 2 diabetic patients. All patients received three treatment regimens, each of 5 days duration in order to reach steady state: 400 mg once daily of dutogliptin (the anticipated clinical dose); 1000 mg metformin twice daily (maximum effective clinical dose); and concomitant administration of 400 mg dutogliptin once daily and 1000 mg metformin twice daily. RESULTS: Co-administration of dutogliptin and metformin did not alter the pharmacokinetics of either agent. The geometric mean ratio, GMR (dutogliptin + metformin/dutogliptin) of the area under the plasma concentration-time curve (AUC(0-24h)) at steady state was 0.91 (90% CI: 0.79-1.06; p = 0.29); the GMR of the maximum plasma concentrations (C(max)) was 0.95 (90% CI: 0.76-1.19; p = 0.70); the time to maximum plasma concentrations (T(max)) was essentially the same for dutogliptin with or without metformin. The GMR (dutogliptin + metformin/metformin) of AUC(0-12h) at steady state was 0.99 (90% CI: 0.84-1.17; p = 0.93); the GMR of C(max) was 0.91 (90% CI: 0.79-1.04; p = 0.18); T(max) was comparable for metformin with or without dutogliptin. Metformin added to dutogliptin had no effect on plasma DPP4 inhibition. All three treatment regimens were well tolerated. CONCLUSIONS: In this small, multiple dose study, the steady state pharmacokinetics of either dutogliptin or metformin were not altered by co-administration of the two agents. Dutogliptin and metformin were well tolerated either alone or in combination and co-administered metformin did not alter the ex vivo DPP4 inhibition by dutogliptin. There is no need to consider pharmacokinetic and pharmacodynamic interactions when determining the dosage of either agent for co-administration. A phase 3 clinical trial is underway to provide more definitive data on the safety and efficacy of dutogliptin administered on a background of metformin treatment.

Pharmacokinetic and pharmacodynamic assessments of the dipeptidyl peptidase-4 inhibitor PHX1149: double-blind, placebo-controlled, single- and multiple-dose studies in healthy subjects.

BACKGROUND: PHX1149 is a dipeptidyl peptidase-4 (DPP4) inhibitor that is currently in clinical development for the treatment of type 2 diabetes mellitus. PHX1149 is a small (molecular weight = 241.16 Da), highly water-soluble (>2 g/mL), orally active molecule with a selectivity index of 15- to 319-fold relative to those of other members of the DPP family. The biochemical median inhibitory concentration of DPP4 is 2.5 nmol/L. OBJECTIVE: The aim of these 2 double-blind, randomized, placebo-controlled studies was to examine the pharmacokinetic (PK) parameters and pharmacodynamic (PD) properties and tolerability of single and multiple ascending doses of PHX1149 in healthy human subjects. METHODS: Healthy men and women aged 18 to 60 years were recruited to participate in a single- or a multiple-dose study in which sequential dose escalation paradigm was used. In the single-dose study, subjects were given a single oral dose of PHX1149 50 to 500 mg or placebo; in the multiple-dose study, subjects were given PHX1149 at doses from 50 to 400 mg or placebo QD for 13 days. There was no intrasubject dose escalation. Blood samples were collected from each subject at a series of time points ranging from 1 hour before to 24 hours after dosing on day 1 in the single- dose study and on days 1, 7, and 13 in the multiple-dose study. PK and PD analyses were performed in plasma samples to determine Cmax, Tmax, AUC0-t, AUC0-infinity, and DPP4 enzymatic activity. The drug accumulation index was also calculated for each dose of PHX1149 in the multiple-dose study. Adverse events (AEs) were monitored in both studies through physical examinations, including measurement of vital signs, and clinical laboratory testing. In both studies, electrocardiography was performed. RESULTS: The single- and multiple-dose studies enrolled 30 and 28 subjects, respectively, for a total enrollment in the 2 studies of 58 healthy adult subjects. The distribution of male and female subjects was 14 (47%) and 16 (53%), respectively, in the single- dose study and 16 (57%) and 12 (43%) in the multiple- dose study. In the single-dose study, 28 (93%) subjects were white; in the multidose study, all subjects were white. The mean (SD) ages in the 2 studies were 51 (10) and 51 (12) years, respectively; and mean (SD) body weights were 89.0 (10.8) and 81.1 (10.9) kg, respectively. PHX1149 exhibited dose-proportional increases in mean Cmax AUC0-t, and AUC0-infinity across the evaluated dose ranges. Tmax ranged from 2 to 4 hours, and t1/2 ranged from approximately 10 to 13 hours. No drug accumulation was observed. Plasma DPP4 inhibition at 24 hours was >or=50% in the multiple-dose study for doses of >or=100 mg. PHX1149 400 mg achieved approximately 90% 24-hour plasma DPP4 inhibition in the multiple-dose study. All AEs were characterized as mild, with the exception of 1 case of moderate edema, which occurred 17 days after the end of dosing in the multiple-dose study (50-mg dose group) and was considered unrelated to the study drug. Adverse events were experienced by 47% of all subjects studied in the single-dose study and 93% of subjects in the multiple-dose study. The rates of AEs were comparable between the study and placebo groups. CONCLUSIONS: The PK parameters and PD properties of PHX1149 were suitable (eg, tl/2, DPP4 inhibition) for once-daily dosing in this group of 58 healthy subjects. All doses were well tolerated.