Bayesian Phase II optimization for time-to-event data based on historical information.

After exploratory drug development, companies face the decision whether to initiate confirmatory trials based on limited efficacy information. This proof-of-concept decision is typically performed after a Phase II trial studying a novel treatment versus either placebo or an active comparator. The article aims to optimize the design of such a proof-of-concept trial with respect to decision making. We incorporate historical information and develop pre-specified decision criteria accounting for the uncertainty of the observed treatment effect. We optimize these criteria based on sensitivity and specificity, given the historical information. Specifically, time-to-event data are considered in a randomized 2-arm trial with additional prior information on the control treatment. The proof-of-concept criterion uses treatment effect size, rather than significance. Criteria are defined on the posterior distribution of the hazard ratio given the Phase II data and the historical control information. Event times are exponentially modeled within groups, allowing for group-specific conjugate prior-to-posterior calculation. While a non-informative prior is placed on the investigational treatment, the control prior is constructed via the meta-analytic-predictive approach. The design parameters including sample size and allocation ratio are then optimized, maximizing the probability of taking the right decision. The approach is illustrated with an example in lung cancer.

An open-label study of the pharmacokinetics and pharmacodynamics of dabigatran etexilate 150mg once daily in Caucasian patients with moderate renal impairment undergoing primary unilateral elective total knee or hip replacement surgery.

BACKGROUND: In adults with moderate renal impairment (creatinine clearance [CrCl] 30-50mL/min) undergoing total hip or knee replacement (THR/TKR), the recommended dose of dabigatran etexilate is 150mg once daily (qd). We investigated the steady state pharmacokinetics, pharmacodynamics and safety in these patients. METHODS: Single-arm, open-label phase 4 study (NCT01184989) in Caucasian patients receiving dabigatran etexilate 75mg 1-4h after surgery and 150mg qd on days 2-10 (TKR) or days 2-35 (THR). Plasma total dabigatran concentrations (day 6±1) were determined by high-performance liquid chromatography tandem mass spectrometry and indirectly using the commercially available diluted thrombin time (dTT) assay (Hemoclot® Thrombin Inhibitors). RESULTS: Of 112 patients (mean CrCl 42.5mL/min, age 79.1years, 69.6% female), 100 completed the study. Geometric mean trough and peak dabigatran concentrations were 47.5ng/mL (10th-90th percentile 19.7-120) and 166ng/mL (49.1-364), respectively. There were four major bleeding events and no venous thromboembolic events. Dabigatran concentrations determined from dTT (and falling within the assay range of 50-500ng/mL) underestimated actual values by 7.6% (90% confidence interval 5.3, 9.9), which is within the acceptance limits of ±15%. CONCLUSIONS: These findings in Caucasians with moderate renal impairment undergoing THR or TKR support the use of the 150mg qd dose of dabigatran etexilate. With adequate set-up, calibration and quality control the dTT assay might be appropriate for situations, such as serious bleeding or a need for urgent surgery, where determination of dabigatran levels would be helpful.

The predictive distribution of the residual variability in the linear-fixed effects model for clinical cross-over trials.

In the linear model for cross-over trials, with fixed subject effects and normal i.i.d. random errors, the residual variability corresponds to the intraindividual variability. While population variances are in general unknown, an estimate can be derived that follows a gamma distribution, where the scale parameter is based on the true unknown variability. This gamma distribution is often used for the sample size calculation for trial planning with the precision approach, where the aim is to achieve in the next trial a predefined precision with a given probability. But then the imprecision in the estimated residual variability or, from a Bayesian perspective, the uncertainty of the unknown variability is not taken into account. Here, we present the predictive distribution for the residual variability, and we investigate a link to the F distribution. The consequence is that in the precision approach more subjects will be necessary than with the conventional calculation. For values of the intraindividual variability that are typical of human pharmacokinetics, that is a gCV of 17-36%, we would need approximately a sixth more subjects.

Mechanisms underlying benign and reversible unconjugated hyperbilirubinemia observed with faldaprevir administration in hepatitis C virus patients.

Faldaprevir, an investigational agent for hepatitis C virus treatment, is well tolerated but associated with rapidly reversible, dose-dependent, clinically benign, unconjugated hyperbilirubinemia. Multidisciplinary preclinical and clinical studies were used to characterize mechanisms underlying this hyperbilirubinemia. In vitro, faldaprevir inhibited key processes involved in bilirubin clearance: UDP glucuronosyltransferase (UGT) 1A1 (UGT1A1) (IC50 0.45 µM), which conjugates bilirubin, and hepatic uptake and efflux transporters, organic anion-transporting polypeptide (OATP) 1B1 (IC50 0.57 µM), OATP1B3 (IC50 0.18 µM), and multidrug resistance-associated protein (MRP) 2 (IC50 6.2 µM), which transport bilirubin and its conjugates. In rat and human hepatocytes, uptake and biliary excretion of [(3)H]bilirubin and/or its glucuronides decreased on coincubation with faldaprevir. In monkeys, faldaprevir (≥20 mg/kg per day) caused reversible unconjugated hyperbilirubinemia, without hemolysis or hepatotoxicity. In clinical studies, faldaprevir-mediated hyperbilirubinemia was predominantly unconjugated, and levels of unconjugated bilirubin correlated with the UGT1A1*28 genotype. The reversible and dose-dependent nature of the clinical hyperbilirubinemia was consistent with competitive inhibition of bilirubin clearance by faldaprevir, and was not associated with liver toxicity or other adverse events. Overall, the reversible, unconjugated hyperbilirubinemia associated with faldaprevir may predominantly result from inhibition of bilirubin conjugation by UGT1A1, with inhibition of hepatic uptake of bilirubin also potentially playing a role. Since OATP1B1/1B3 are known to be involved in hepatic uptake of circulating bilirubin glucuronides, inhibition of OATP1B1/1B3 and MRP2 may underlie isolated increases in conjugated bilirubin. As such, faldaprevir-mediated hyperbilirubinemia is not associated with any liver injury or toxicity, and is considered to result from decreased bilirubin elimination due to a drug-bilirubin interaction.

The effect of dabigatran plasma concentrations and patient characteristics on the frequency of ischemic stroke and major bleeding in atrial fibrillation patients: the RE-LY Trial (Randomized Evaluation of Long-Term Anticoagulation Therapy).

OBJECTIVES: The goal of this study was to analyze the impact of dabigatran plasma concentrations, patient demographics, and aspirin (ASA) use on frequencies of ischemic strokes/systemic emboli and major bleeds in atrial fibrillation patients. BACKGROUND: The efficacy and safety of dabigatran etexilate were demonstrated in the RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) trial, but a therapeutic concentration range has not been defined. METHODS: In a pre-specified analysis of RE-LY, plasma concentrations of dabigatran were determined in patients treated with dabigatran etexilate 110 mg twice daily (bid) or 150 mg bid and correlated with the clinical outcomes of ischemic stroke/systemic embolism and major bleeding using univariate and multivariate logistic regression and Cox regression models. Patient demographics and ASA use were assessed descriptively and as covariates. RESULTS: Plasma concentrations were obtained from 9,183 patients, with 112 ischemic strokes/systemic emboli (1.3%) and 323 major bleeds (3.8%) recorded. Dabigatran levels were dependent on renal function, age, weight, and female sex, but not ethnicity, geographic region, ASA use, or clopidogrel use. A multiple logistic regression model (c-statistic 0.657, 95% confidence interval [CI]: 0.61 to 0.71) showed that the risk of ischemic events was inversely related to trough dabigatran concentrations (p = 0.045), with age and previous stroke (both p < 0.0001) as significant covariates. Multiple logistic regression (c-statistic 0.715, 95% CI: 0.69 to 0.74) showed major bleeding risk increased with dabigatran exposure (p < 0.0001), age (p < 0.0001), ASA use (p < 0.0003), and diabetes (p = 0.018) as significant covariates. CONCLUSIONS: Ischemic stroke and bleeding outcomes were correlated with dabigatran plasma concentrations. Age was the most important covariate. Individual benefit-risk might be improved by tailoring dabigatran dose after considering selected patient characteristics. (Randomized Evaluation of Long Term Anticoagulant Therapy [RE-LY] With Dabigatran Etexilate; NCT00262600).

Antiviral effect, safety, and pharmacokinetics of five-day oral administration of Deleobuvir (BI 207127), an investigational hepatitis C virus RNA polymerase inhibitor, in patients with chronic hepatitis C.

Deleobuvir (BI 207127) is an investigational oral nonnucleoside inhibitor of hepatitis C virus (HCV) NS5B RNA polymerase. Antiviral activity, virology, pharmacokinetics, and safety were assessed in HCV genotype 1-infected patients receiving 5 days' deleobuvir monotherapy. In this double-blind phase 1b study, treatment-naive (TN; n = 15) and treatment-experienced (TE; n = 45) patients without cirrhosis received placebo or deleobuvir at 100, 200, 400, 800, or 1,200 mg every 8 h (q8h) for 5 days. Patients with cirrhosis (n = 13) received deleobuvir at 400 or 600 mg q8h for 5 days. Virologic analyses included NS5B genotyping and phenotyping of individual isolates. At day 5, patients without cirrhosis had dose-dependent median HCV RNA reductions of up to 3.8 log10 (with no placebo response); patients with cirrhosis had median HCV RNA reductions of approximately 3.0 log10. Three patients discontinued due to adverse events (AEs). The most common AEs were gastrointestinal, nervous system, and skin/cutaneous tissue disorders. Plasma exposure of deleobuvir was supraproportional at doses ≥ 400 mg q8h and approximately 2-fold higher in patients with cirrhosis than in patients without cirrhosis. No virologic breakthrough was observed. NS5B substitutions associated with deleobuvir resistance in vitro were detected in 9/59 patients; seven encoded P495 substitutions, including P495L, which conferred 120- to 310-fold-decreased sensitivity to deleobuvir. P495 variants did not persist in follow-up without selective drug pressure. Deleobuvir monotherapy was generally well tolerated and demonstrated dose-dependent antiviral activity against HCV genotype 1 over 5 days.

Faldaprevir (BI 201335), deleobuvir (BI 207127) and ribavirin oral therapy for treatment-naive HCV genotype 1: SOUND-C1 final results.

BACKGROUND: Faldaprevir (BI 201335) and deleobuvir (BI 207127) are direct-acting antiviral agents under development for the treatment of chronic HCV infection. This article describes the final results of the Phase Ib SOUND-C1 study that evaluated the interferon-free oral combination of faldaprevir, deleobuvir and ribavirin in 32 treatment-naive patients infected with HCV genotype 1. METHODS: Patients were randomized to receive deleobuvir 400 mg (n=15) or 600 mg (n=17) three times daily plus faldaprevir 120 mg once daily and weight-based ribavirin for 4 weeks. Interferon-free therapy was followed by response-guided faldaprevir plus pegylated interferon-α2a/ribavirin to week 24 or 48. RESULTS: At week 4, 73% (11/15) and 100% (17/17) of patients in the deleobuvir 400 mg and 600 mg groups achieved HCV RNA<25 IU/ml, respectively. During interferon-free treatment, virological breakthrough was reported in one patient and re-increase of HCV RNA in one patient. Both patients were successfully treated with interferon-containing therapy. The rate of sustained virological response 24 weeks after completion of treatment was 73% (11/15) in the deleobuvir 400 mg group and 94% (16/17) in the 600 mg group. During faldaprevir plus pegylated interferon-α2a/ribavirin treatment, the most common adverse events were pruritus (38% of patients), rash (31%) and asthenia (31%); these were severe in approximately 3% of patients. CONCLUSIONS: Potent antiviral activity and favourable safety of the treatment regimen were demonstrated. Furthermore, the results suggest that patients with breakthrough at week 4 may be rescued with an interferon-containing regimen. Clinical trials.gov number NCT01132313.

Faldaprevir combined with peginterferon alfa-2a and ribavirin in chronic hepatitis C virus genotype-1 patients with prior nonresponse: SILEN-C2 trial.

UNLABELLED: Faldaprevir (BI 201335) is a potent, hepatitis C virus (HCV) NS3/4A protease inhibitor. In all, 290 noncirrhotic HCV genotype (GT)-1 patients with prior null (<1 log10 viral load [VL] drop at any time on treatment) or partial response (≥1 log10 VL drop but never undetectable on treatment) were randomized 2:1:1 to receive 48 weeks of peginterferon alfa-2a and ribavirin (PegIFN/RBV) in combination with faldaprevir 240 mg once daily (QD) with 3 days PegIFN/RBV lead-in (LI), 240 mg QD without LI, or 240 mg twice daily (BID) with LI. Patients in the 240 mg QD/LI group achieving maintained rapid virologic response (mRVR; VL <25 IU/mL [Roche TaqMan] at week 4 and undetectable at weeks 8 to 20) were rerandomized to cease all treatment at week 24 or continue PegIFN/RBV up to week 48. Sustained virologic response (SVR) rates were 32%, 50%, and 42% in prior partial responders, and 21%, 35%, and 29% in prior null responders in the faldaprevir 240 mg QD/LI, 240 mg QD, and 240 mg BID/LI groups, respectively. In the 240 mg QD/LI group, a significantly higher proportion of mRVR patients rerandomized to 48 weeks' treatment achieved SVR compared with those assigned to 24 weeks treatment (72% versus 43%; P = 0.035). Rates of gastrointestinal disorders, jaundice, dry skin, and photosensitivity were increased at 240 mg BID compared with the 240 mg QD dose. Faldaprevir discontinuations owing to adverse events occurred in 6%, 4%, and 23% of patients in the 240 mg QD/LI, 240 mg QD, and 240 mg BID/LI groups, respectively. CONCLUSION: Faldaprevir 240 mg QD with PegIFN/RBV was safe and tolerable and produced substantial SVR rates in prior null and partial responders. The 240 mg QD dose is currently undergoing phase 3 evaluation.

Faldaprevir combined with pegylated interferon alfa-2a and ribavirin in treatment-naïve patients with chronic genotype 1 HCV: SILEN-C1 trial.

UNLABELLED: Faldaprevir (BI 201335) is a potent, hepatitis C virus (HCV) NS3/4A protease inhibitor with pharmacokinetic properties supportive of once-daily (QD) dosing. Four hundred and twenty-nine HCV genotype (GT)-1 treatment-naïve patients without cirrhosis were randomized 1:1:2:2 to receive 24 weeks of pegylated interferon alfa-2a and ribavirin (PegIFN/RBV) in combination with placebo, faldaprevir 120 mg QD with 3 days of PegIFN/RBV lead-in (LI), 240 mg QD with LI, or 240 mg QD without LI, followed by an additional 24 weeks of PegIFN/RBV. Patients in the 240 mg QD groups achieving maintained rapid virologic response (mRVR; viral load [VL] <25 IU/mL at week 4 and undetectable at weeks 8-20) were rerandomized to cease all treatment at week 24 or continue receiving PegIFN/RBV up to week 48. VL was measured by Roche TaqMan. Sustained virologic response (SVR) rates were 56%, 72%, 72%, and 84% in the placebo, faldaprevir 120 mg QD/LI, 240 mg QD/LI, and 240 mg QD groups. Ninety-two percent of mRVR patients treated with faldaprevir 240 mg QD achieved SVR, irrespective of PegIFN/RBV treatment duration. Eighty-two percent of GT-1a patients who received faldaprevir 240 mg QD achieved SVR versus 47% with placebo. Mild gastrointestinal disorders, jaundice resulting from isolated unconjugated hyperbilirubinemia, and rash or photosensitivity were more common in the active groups than with placebo. Discontinuations resulting from adverse events occurred in 4%, 11%, and 5% of patients treated with 120 mg QD/LI, 240 mg QD/LI, and 240 mg QD of faldaprevir versus 1% with placebo. CONCLUSION: Faldaprevir QD with PegIFN/RBV achieved consistently high SVR rates with acceptable tolerability and safety at all dose levels. The 120 and 240 mg QD doses are currently undergoing phase 3 evaluation. (HEPATOLOGY 2013;57:2143-2154).

Empagliflozin (BI 10773), a Potent and Selective SGLT2 Inhibitor, Induces Dose-Dependent Glucosuria in Healthy Subjects.

Empagliflozin is an orally available, selective inhibitor of sodium glucose cotransporter 2. In this study, single oral doses of empagliflozin from 0.5 to 800 mg were not associated with any clinically significant safety concerns in healthy male volunteers. The incidence of adverse events (AEs) was similar in subjects receiving placebo (22.2%) or empagliflozin (25.0%) in the single rising dose part of the study and after 50 mg empagliflozin under fed (28.6%) or fasted (28.6%) conditions. The most frequent AE was headache. No clinically relevant changes in laboratory or electrocardiogram (ECG) measurements were observed. Single oral doses of empagliflozin were rapidly absorbed, reaching peak levels after 1.0-2.1 hours. Increases in empagliflozin exposure were roughly dose-proportional and a dose-dependent increase in urinary glucose excretion was observed for empagliflozin doses up to 100 mg. After ingestion of 50 mg empagliflozin in conjunction with a high-fat, high-calorie meal, no clinically relevant changes in exposure were found, indicating that empagliflozin can be administered independent of food. Empagliflozin up to 800 mg did not generate clinically significant safety concerns in healthy male subjects. The pharmacokinetic properties of empagliflozin support once daily administration independent of food.

Oral bioavailability of dabigatran etexilate (Pradaxa(®) ) after co-medication with verapamil in healthy subjects.

AIM: To investigate the effect of the P-glycoprotein inhibitor verapamil on the pharmacokinetics and pharmacodynamics of dabigatran etexilate (DE). METHOD: In this two part multiple crossover trial in 40 healthy subjects, DE 150 mg was given alone or with verapamil at different doses, duration of treatment (single vs. multiple dosing), formulations, and timings (before, concurrently or after DE). Primary pharmacokinetic endpoints were determined from concentrations of total dabigatran (unconjugated plus conjugated). Pharmacodynamic endpoints were determined from clotting time. RESULTS: The greatest effect was observed with single dose verapamil 120 mg immediate release given 1 h before single dose DE. Geometric mean area under the plasma concentration curve [AUC(0,∞)] and maximum analyte concentration in the plasma (Cmax ) were increased by 143% [90% confidence interval (CI) 91, 208] and 179% (90% CI 115, 262), respectively. The effect was reduced to a 71% and 91% increase in AUC and Cmax , respectively, when DE was administered with verapamil 240 mg extended release. After multiple verapamil dosing, DE AUC(0,∞) and Cmax increases were 54% and 63%, respectively. However, DE given 2 h before verapamil increased DE AUC(0,∞) and Cmax by <20%. With regard to clotting prolongation, the dabigatran plasma concentration-effect relationship was generally not affected by the co-administration of verapamil. Concomitant administration of DE and verapamil did not reveal any unexpected safety findings. CONCLUSION: Verapamil increased DE bioavailability, likely due to inhibition of P-glycoprotein. Our results suggest that an interaction between verapamil and DE can be minimized if DE is administered 2 h prior to verapamil.

Decrease in the oral bioavailability of dabigatran etexilate after co-medication with rifampicin.

AIMS: This study examined the effects of the CYP3A/P-glycoprotein inducer, rifampicin, on the pharmacokinetics of dabigatran following oral administration of the prodrug, dabigatran etexilate. METHODS: This was an open-label, fixed-sequence, four-period study in healthy volunteers. Subjects received a single dose of dabigatran etexilate 150 mg on day 1, rifampicin 600 mg once daily on days 2-8, and single doses of dabigatran etexilate on days 9, 16 and 23. RESULTS: Twenty-four subjects were treated, of whom 22 received all treatments. Relative to the reference (single dose of dabigatran etexilate alone; treatment A), administration of dabigatran etexilate following 7 days of rifampicin (treatment B) decreased the geometric mean (gMean) area under the concentration-time curve (AUC(0-∞)) and maximal plasma concentration (C(max)) of total dabigatran by 67 and 65.5%, respectively. The time to peak and the terminal half-life were not affected. The gMean ratio for the primary comparison (treatment B vs. treatment A) was 33.0% (90% confidence interval 26.5, 41.2%) for AUC(0-∞) and 34.5% (90% confidence interval 26.9, 44.1%) for C(max), indicating a significant effect on total dabigatran exposure (total pharmacologically active dabigatran represents the sum of nonconjugated dabigatran and dabigatran glucuronide). After a 7 day (treatment C) or 14 day washout (treatment D), the AUC(0-∞) and C(max) of dabigatran were reduced by 18 and 20%, and by 15 and 20%, respectively, compared with treatment A, which was considered not clinically relevant. The overall safety profile of all treatments was good. CONCLUSIONS: Administration of rifampicin for 7 days resulted in a significant reduction in the bioavailability of dabigatran, which returned almost to baseline after 7 days washout.

Efficacy of the protease inhibitor BI 201335, polymerase inhibitor BI 207127, and ribavirin in patients with chronic HCV infection.

BACKGROUND & AIMS: Therapeutic regimens are being developed for patients with hepatitis C virus (HCV) infection that do not include the combination of peginterferon alfa and ribavirin. We investigated the antiviral effect and safety of BI 201335 (an inhibitor of the NS3/4A protease) and BI 207127 (an inhibitor of the NS5B non-nucleoside polymerase) with ribavirin. METHODS: Thirty-two treatment-naïve patients with chronic HCV genotype 1 infection were randomly assigned to groups that were given 400 mg or 600 mg BI 207127 3 times daily plus 120 mg BI 201335 once daily and 1000 to 1200 mg/day ribavirin for 4 weeks. The primary efficacy end point was virologic response (HCV RNA level <25 IU/mL at week 4). Thirty-two patients received treatment; 31 completed all 4 weeks of assigned combination therapy. RESULTS: In the group given BI 207127 400 mg 3 times daily, the rates of virologic response were 47%, 67%, and 73% at days 15, 22, and 29; a higher rate of response was observed in patients with genotype-1b compared with genotype-1a infections. In the group given BI 207127 600 mg 3 times daily, the rates of virologic response were 82%, 100%, and 100%, respectively, and did not differ among genotypes. One patient in the group given 400 mg 3 times daily had virologic breakthrough (≥1 log(10) rebound in HCV RNA) at day 22. The most frequent adverse events were mild gastrointestinal disorders, rash, and photosensitivity. There were no severe or serious adverse events; no patients discontinued therapy prematurely. CONCLUSIONS: The combination of the protease inhibitor BI 201335, the polymerase inhibitor BI 207127, and ribavirin has rapid and strong activity against HCV genotype-1 and did not cause serious or severe adverse events.

Safety, pharmacokinetics and antiviral effect of BILB 1941, a novel hepatitis C virus RNA polymerase inhibitor, after 5 days oral treatment.

BACKGROUND: BILB 1941 is a potent and specific nonnucleoside inhibitor of the hepatitis C virus (HCV) RNA polymerase in vitro. METHODS: In a double-blind sequential group comparison, 96 male HCV genotype 1 patients with minimal to mild liver fibrosis (Ishak or Metavir score 0-2) were randomized (8 to active treatment and 2 to placebo per dose group) and treated with 10-450 mg BILB 1941 every 8 h over 5 days. Viral load (VL) was measured using Roche Cobas TaqMan assays. RESULTS: VL decreased by > or =1 log10 IU/ml in 2/8, 2/8, 1/8, 2/7, 0/8, 2/8 and 4/5 patients on 60, 80, 100, 150, 200, 300 and 450 mg, respectively. No response was seen with placebo. HCV subtype 1b showed better response than 1a, the effect of other covariables including prior interferon treatment was not significant. NS5B population sequencing and phenotyping identified baseline samples with reduced BILB 1941 susceptibility, but did not detect an on-treatment emergence of resistant mutants. Plasma drug levels were linear until 300 mg. No serious adverse events (AEs) were reported. AEs were mainly gastrointestinal-related (most frequent diarrhoea) and frequency increased with dose. On 450 mg, all five active-treated patients discontinued (four for gastrointestinal intolerance and one for increased aspartate aminotransferase and alanine aminotransferase levels) and the trial was discontinued. CONCLUSIONS: BILB 1941 monotherapy demonstrated antiviral activity against HCV genotype 1, but gastrointestinal intolerance precluded testing of higher doses.

Dabigatran with or without concomitant aspirin compared with warfarin alone in patients with nonvalvular atrial fibrillation (PETRO Study).

This is the first evaluation of dabigatran, an oral direct thrombin inhibitor, in patients with atrial fibrillation (AF). Patients (n = 502) were randomized to receive blinded doses of 50-, 150-, or 300-mg dabigatran twice daily alone or combined with 81- or 325-mg aspirin or open-label warfarin administered to achieve an international normalized ratio of 2 to 3 for 12 weeks. Dabigatran plasma concentrations, activated partial thromboplastin time, D-dimer, urinary 11-dehydrothromboxane B(2) (DTB2), and liver function were measured at baseline and at 1, 2, 4, 8, and 12 weeks. Clinical end points were assessed according to the treatment received at the time of the event. Overall, 92% of patients completed the study. Major hemorrhages were limited to the group treated with 300-mg dabigatran plus aspirin (4 of 64), and the incidence was significant versus 300-mg dabigatran alone (0 of 105, p <0.02). Total bleeding events were more frequent in the 300-mg (39 of 169, 23%) and 150-mg (30 of 169, 18%) dabigatran groups compared with the 50-mg groups (7 of 107, 7%; p = 0.0002 and p = 0.01, respectively). Thromboembolic events were limited to the 50-mg dabigatran dose groups (2 of 107, 2%). The mean trough d-dimer measurements were suppressed for the 2 highest doses of dabigatran and warfarin (international normalized ratio of 2 to 3). Aminotransferase levels >3 times the upper limit of normal were observed in 0.9% of the dabigatran recipients and in none of the warfarin recipients. Two dabigatran recipients had aminotransferase levels >5 times the upper limit of normal as a result of gallstones, which resolved. Trough activated partial thromboplastin time values were 1.2, 1.5, and 1.8 times the baseline level for the 50-, 150-, and 300-mg dabigatran groups, respectively. DTB2 concentrations after 12 weeks of 50-, 150-, and 300-mg dabigatran treatment were increased by 31%, 17%, and 23%, respectively, versus baseline (p = 0.02, p = 0.03, and p = 0.0004). In conclusion, major bleeding events were limited to patients treated with dabigatran 300 mg plus aspirin and thromboembolic episodes were limited to the 50-mg dabigatran groups. The 2 highest doses of dabigatran suppress D-dimer concentrations. Serious liver toxicity was not seen. The significance of the increase of DTB2 concentrations in dabigatran-treated patients needs resolution.

Viral kinetics in patients with chronic hepatitis C treated with the serine protease inhibitor BILN 2061.

We analysed viral kinetics from a 2-day treatment with BILN 2061, a serine protease inhibitor of hepatitis C virus, in patients chronically infected with genotype 1 hepatitis C virus. The efficiency (E), describing inhibition of viral production, was above 99.45% in all patients with minor or moderate fibrosis receiving doses of 200mg and 500 mg twice daily and larger than in previous studies for interferon-based treatments. However, epsilon was slightly smaller in patients with cirrhosis given 200mg and markedly smaller in patients given 25 mg. Estimates of viral clearance and infected-cell loss support conclusions on these rates and on treatment mechanisms from previous studies on interferon-alpha-based treatments.

Pharmacokinetic profile of the oral direct thrombin inhibitor dabigatran etexilate in healthy volunteers and patients undergoing total hip replacement.

Dabigatran etexilate is an oral low-molecular-weight direct thrombin inhibitor. Following oral administration, dabigatran etexilate is rapidly converted to its active form, dabigatran. The authors investigated the absorption, distribution, and elimination of a single 150-mg dose capsule formulation of dabigatran etexilate in healthy volunteers and patients undergoing total hip replacement. In an open-label, 3-way crossover study, dabigatran etexilate was administered to 18 male volunteers in the fasted state, after administration of food and with coadministration of the proton pump inhibitor, pantoprazole. In a subsequent multicenter, open-label study, 59 patients received a single dose of dabigatran etexilate, administered 1 to 3 hours following total hip replacement. In healthy volunteers, food had no effect on the extent of absorption of dabigatran etexilate, although there was reduced interindividual variability for dabigatran maximum plasma concentration and AUC(0-infinity). A decrease in the mean dabigatran AUC(0-infinity) (904 to 705 ng*h/mL) occurred with coadministration of pantoprazole. In patients undergoing total hip replacement, immediate onset of absorption was seen with the maximum plasma concentration of dabigatran occurring after 6 hours. The AUC(0-24) of dabigatran was 88% of the steady-state AUC using a preliminary tablet formulation and 106% of that seen in the healthy volunteer study. Compared with healthy volunteers, the postoperative profile was flattened with delayed peak concentrations. In summary, administration of the dabigatran etexilate capsule with food has no effect on the extent of dabigatran absorption, with a moderate decrease when coadministered with pantoprazole. Adequate plasma concentrations of dabigatran were seen with early postoperative administration of the dabigatran etexilate capsule. These pharmacokinetic characteristics confirm the suitability of this oral solid dosage form for use in future clinical trials.

Antiviral efficacy of NS3-serine protease inhibitor BILN-2061 in patients with chronic genotype 2 and 3 hepatitis C.

BILN-2061, a specific and potent peptidomimetic inhibitor of the HCV NS3 protease, has recently been shown to markedly lower serum hepatitis C virus (HCV)-RNA levels in patients chronically infected with HCV genotype 1 in three 2-day proof of principle studies. The aim of the current study was to assess the antiviral efficacy of BILN-2061 in patients with genotypes 2 and 3 HCV infection. The antiviral efficacy, pharmacokinetics, and tolerability of 500 mg twice-daily BILN-2061 given as monotherapy for 2 days in 10 patients chronically infected with non-genotype 1 HCV (genotype 2: n = 3; genotype 3: n =7) and minimal liver fibrosis (Ishak score 0-2) were assessed in a placebo-controlled (placebo n = 2), double-blind pilot study. HCV-RNA levels decreased by > or =1 log(10) copies/mL in 4 of 8 patients treated with BILN-2061. One patient showed a weak response of <1 log(10) copies/mL. Three of 8 treated patients showed no response. There was no correlation between baseline viral concentration or genotype and response. BILN-2061 exhibited good systemic exposure after oral administration and was well tolerated. In conclusion, the antiviral efficacy of the HCV serine protease inhibitor BILN-2061 is less pronounced and more variable in patients with HCV genotype 2 or 3 infection compared with previous results in patients with HCV genotype 1. A lower affinity of BILN-2061 for the NS3 protease of genotypes 2 and 3 HCV is most likely a major contributor to these findings.

Short-term antiviral efficacy of BILN 2061, a hepatitis C virus serine protease inhibitor, in hepatitis C genotype 1 patients.

BACKGROUND AND AIMS: Novel, potent, and well-tolerated hepatitis C virus (HCV) drugs are needed. BILN 2061 is a potent and specific inhibitor of HCV serine protease in vitro. Preclinical toxicology data and studies in healthy volunteers supported the administration of BILN 2061 to patients with HCV infection. METHODS: The antiviral efficacy, pharmacokinetics, and tolerability of 25, 200, and 500 mg BILN 2061 twice daily given as monotherapy for 2 days in 31 patients infected with chronic genotype 1 HCV infection and with minimal liver fibrosis (Ishak score of 0-2) were assessed in a placebo-controlled, double-blind pilot study. In 2 subsequent placebo-controlled studies of similar design, 200 mg BILN 2061 twice daily was administered for 2 days to 10 patients with advanced liver fibrosis (Ishak score of 3 or 4) and to 10 patients with compensated cirrhosis (Ishak score of 5 or 6). RESULTS: Viral RNA reductions of 2-3 log 10 copies/mL were achieved in most of the patients. There was a trend toward a higher number of patients receiving 500 mg BILN 2061 achieving a viral RNA reduction > or =3 log(10) copies/mL as compared with patients receiving 25 mg BILN 2061. Advanced fibrosis or compensated cirrhosis did not affect the antiviral efficacy of BILN 2061. BILN 2061 was well tolerated in all studies. CONCLUSIONS: BILN 2061 is a well-tolerated and very active compound that reduced serum viral RNA concentrations after 2 days of treatment in patients infected with genotype 1 HCV independent of the degree of fibrosis. Nevertheless, further clinical trials are on hold pending resolution of animal toxicity issues.