Pharmacokinetics and pharmacodynamics of setrobuvir, an orally administered hepatitis C virus non-nucleoside analogue inhibitor.

PURPOSE: New antiviral agents with activity against hepatitis C virus (HCV) are needed to optimize treatment for chronic hepatitis C (CHC). We evaluated the pharmacokinetics of setrobuvir (a non-nucleoside HCV polymerase inhibitor) in healthy volunteers (study 1 & 2) and its antiviral efficacy in patients with genotype 1, noncirrhotic treatment-naive CHC (study 3). METHODS: Three studies investigated the pharmacokinetics and pharmacodynamics of setrobuvir. First, sequential cohorts of volunteers were randomly assigned to receive single oral doses of setrobuvir 400 to 3000 mg or placebo in a double-blind, ascending dose study. In the second study, volunteers were randomly assigned to receive multiple doses of setrobuvir (400 or 800 mg once daily [QD] or 600 mg twice a day [BID]). In the third study, patients with genotype 1 CHC received setrobuvir (200, 400, or 800 mg) or placebo BID for 3 days. FINDINGS: After single doses of setrobuvir (400-3000 mg) to volunteers in a fasted state, peak Cmax and AUC0-∞ increased in a less than dose-proportional manner. The mean apparent t½z ranged from 22.0 to 31.3 hours and was not dose related. Cmax and AUC increased significantly (4.3- and 6.3-fold, respectively) in volunteers who received 2000 mg with a high-fat meal versus fasting. After multiple oral doses, steady state was achieved after 7 days of dosing (400 or 800 mg QD and 600 mg BID) and accumulation was dose-independent. Mean day 14 plasma exposure increased in a less than dose-proportional manner in volunteers who received 400 and 800 mg QD, but it was more than dose-proportional in volunteers receiving 600 mg BID. Dose did not affect the mean t½z (range, 24.1-26.6 hours), apparent oral clearance (0.254-0.516 L/h), or apparent volume of distribution (9.60-18.1 L). In patients with CHC, dose-related reductions in HCV RNA concentration were apparent within 24 hours of the start of treatment. Reductions from baseline to the end of treatment (day 3) in patients treated with setrobuvir 200, 400, and 800 mg BID were -2.1, -2.2, and -2.9 log10 IU/mL, respectively (vs ≤0.1 log10 IU/mL with placebo). Reductions in HCV RNA were greater in patients with genotype 1b (range, -2.7 to -3.1 log10 IU/mL) than in patients with genotype 1a (range, -1.3 to -2.7 log10 IU/mL). Setrobuvir was well tolerated, with no serious adverse events. IMPLICATIONS: The steady state pharmacokinetics of setrobuvir appear to be dose proportional, and setrobuvir produces a mean reduction of 2.9 log10 IU/mL in HCV RNA over 3 days in patients with genotype 1 (a and b) treated with 800 mg BID. ClinicalTrials.gov identifier: NCT00782353.

Potent immune activation in chronic hepatitis C patients upon administration of an oral inducer of endogenous interferons that acts via Toll-like receptor 7.

BACKGROUND: ANA773, an oral prodrug of a small-molecule Toll-like receptor (TLR)7 agonist, induces a dose-related decrease in serum HCV RNA levels in chronic hepatitis C patients. METHODS: The prodrug ANA773 was administered to healthy individuals and chronic hepatitis C patients. At different time points during the course of treatment, modulation of the phenotype and function of peripheral leukocytes were evaluated to determine the role of distinct immune cells on the clinical outcome of therapy. RESULTS: Early after administration of the TLR7 agonist, a mild transient reduction of the number of lymphocytes was observed in both healthy individuals and chronic hepatitis C patients. Moreover, repeated administration of ANA773 resulted in transiently reduced numbers of myeloid and plasmacytoid dendritic cells (DC) in blood. Interestingly, reduced plasmacytoid DC numbers as well as increased serum interferon (IFN)-α and IFN-γ inducible protein (IP)-10 levels were observed only in virological responders (≥1 log(10) IU/ml reduction of HCV RNA levels upon ANA773 treatment), but were absent in virological non-responders. In vitro stimulation of peripheral blood mononuclear cells from virological responders showed a high frequency of IFN-α-producing plasmacytoid DC upon stimulation in vitro with ANA773, whereas no IFN-α was induced in non-responders. CONCLUSIONS: These findings indicate that the viral load decline in chronic hepatitis C patients treated with the TLR7 agonist ANA773 is likely due to intrinsic differences in the induction of endogenous IFNs and IFN-stimulated gene products (IFN-α and IP-10) upon TLR7 ligation.

Pharmacokinetics and metabolism of anecortave acetate in animals and humans.

The ocular delivery of anecortave acetate was tested in preclinical and clinical pharmacokinetic and metabolism studies. Results of initial studies led to the design of a new cannula that could effectively deliver anecortave acetate as a posterior juxtascleral depot, providing adequate retinal and choroidal drug concentrations for up to 6 months after a single administration. A counter-pressure device was designed to prevent drug reflux during and immediately after posterior juxtascleral depot administration. Pharmacokinetic studies support the effectiveness of these devices. Anecortave acetate is rapidly hydrolyzed by esterases to pharmacologically active anecortave desacetate, and is further reductively metabolized to one major and several minor products that circulate as glucuronide conjugates. Low levels of these anecortave acetate metabolites were detectable for only approximately 2 weeks in the plasma after a 15-mg posterior juxtascleral depot administration to age-related macular degeneration patients. Studies show that posterior juxtascleral depot administration of anecortave acetate is an effective, minimally invasive method of delivering this drug to the choroid and retina.

Effect of tolterodine on the anticoagulant actions and pharmacokinetics of single-dose warfarin in healthy volunteers.

This randomized, double-blind, crossover study investigated the potential effects of tolterodine ((R)-N,N-diisopropyl-3-(2-hydroxy-5-methyl-phenyl)-3-phenylpropanamine, CAS 124937-51-5), an antimuscarinic agent for the treatment of the overactive bladder, on the anticoagulant actions and pharmacokinetics of single-dose warfarin (CAS 81-81-2) in 20 healthy male volunteers. In terms of study design, volunteers randomly received oral tolterodine L-tartrate (2 mg twice daily) or matching placebo for 7 days, with a single oral dose of warfarin (25 mg) administered on day 4 of each treatment period. R-(+)- and S-(-)-warfarin pharmacokinetics were estimated from plasma levels measured up to 96 h post-dose, in conjunction with assessment of prothrombin time and factor VII activity. Pharmacokinetics of tolterodine and its active 5-hydroxymethyl metabolite ((R)-N,N-diisopropyl-3-(2-hydroxy-5-hydroxymethyl-phenyl)-3-phenylpropanamine; 5-HM), in the presence and absence of warfarin, were also determined. Relative to placebo, tolterodine had no discernible effect on the anticoagulant actions of warfarin. Point estimates of the tolterodine: placebo ratios for prothrombin time and factor VII activity were 1.00 (90% confidence interval [CI]: 0.91-1.10) and 0.91 (90% CI: 0.83-0.99), respectively, consistent with equivalence. No clinically significant changes in the pharmacokinetics of R-(+)- and S-(-)-warfarin were noted. Serum concentration-time profiles and the pharmacokinetics of tolterodine and 5-HM were similar in the presence and absence of warfarin. There were no safety concerns. These findings indicate that co-administration of tolterodine and warfarin is safe and well tolerated, with no clinically significant pharmacodynamic or kinetic interaction in healthy volunteers.