Use of a cocktail probe to assess potential drug interactions with cytochrome P450 after administration of belatacept, a costimulatory immunomodulator.

AIM: This open-label study investigated the effect of belatacept on cytokine levels and on the pharmacokinetics of caffeine, losartan, omeprazole, dextromethorphan and midazolam, as CYP probe substrates after oral administration of the Inje cocktail in healthy volunteers. METHODS: Twenty-two evaluable subjects received the Inje cocktail on Days 1, 4, 7 and 11 and belatacept infusion on Day 4. RESULTS: Since belatacept caused no major alterations to cytokine levels, there were no major effects on CYP-substrate pharmacokinetics, except for a slight (16-30%) increase in omeprazole exposure, which was probably due to omeprazole-mediated, time-dependent CYP inhibition. Belatacept did not cause major alterations in the pharmacokinetics, as measured by the geometric mean ratios and associated 90% confidence interval for area under the plasma concentration -time curve from time zero to infinity on Day 7 comparing administration with and without belatacept for caffeine (1.002 [0.914, 1.098]), dextromethorphan (1.031 [0.885, 1.200]), losartan (1.016 [0.938, 1.101)], midazolam (0.968 [0.892, 1.049]) or their respective metabolites. CONCLUSIONS: Therefore, no dose adjustments of CYP substrates are indicated with belatacept coadministration.

The pharmacokinetics of peginterferon lambda-1a following single dose administration to subjects with impaired renal function.

AIMS: This open label study was conducted to assess the effect of renal impairment (RI) on the pharmacokinetics (PK) of peginterferon lambda-1a (Lambda). METHODS: Subjects (age 18-75 years, BMI 18-35 kg m(-2) ) were enrolled into one of five renal function groups: normal (n = 12), mild RI (n = 8), moderate RI (n = 8), severe RI (n = 7), end-stage renal disease (ESRD, n = 8) based on estimated glomerular filtration rate (eGFR) calculated using the Modification of Diet in Renal Disease (MDRD) equation. Subjects received a single dose of Lambda (180 µg) subcutaneously on day 1 followed by PK serum sample collections through day 29. Safety, tolerability and immunogenicity data were collected through day 43. PK parameters were estimated and summarized by group. Geometric mean ratios (GMR) and 90% confidence intervals (CIs) were calculated between normal and RI groups. RESULTS: With decreasing eGFR, Lambda exposure (Cmax , AUC) increased while apparent clearance (CL/F) and apparent volume of distribution (V/F) decreased. Relative to subjects with normal renal function (geometric mean AUC = 99.5 ng ml(-1) h), Lambda exposure estimates (AUC) were slightly increased in the mild RI group (geometric mean [90% CI]: 1.20 [0.82, 1.77]) and greater in the moderate (1.95 [1.35, 2.83]), severe RI (1.95 [1.30, 2.93]) and ESRD (1.88 [1.30, 2.73]) groups. Lambda was generally well tolerated. CONCLUSIONS: The results demonstrated that RI reduces the clearance of Lambda and suggests that dose modifications may not be required in patients with mild RI but may be required in patients with moderate to severe RI or ESRD.

Pharmacodynamics, safety, and pharmacokinetics of BMS-663068, an oral HIV-1 attachment inhibitor in HIV-1-infected subjects.

BACKGROUND: BMS-663068 is a prodrug of the small-molecule inhibitor BMS-626529, which inhibits human immunodeficiency virus type 1 (HIV-1) infection by binding to gp120 and interfering with the attachment of virus to CD4+ T-cells. METHODS: Fifty HIV-1-infected subjects were randomized to 1 of 5 regimen groups (600 mg BMS-663068 plus 100 mg ritonavir every 12 hours [Q12H], 1200 mg BMS-663068 plus 100 mg ritonavir every bedtime, 1200 mg BMS-663068 plus 100 mg ritonavir Q12H, 1200 mg BMS-663068 Q12H plus 100 mg ritonavir every morning, or 1200 mg BMS-663068 Q12H) for 8 days in this open-label, multiple-dose, parallel study. The study assessed the pharmacodynamics, pharmacokinetics, and safety of BMS-663068. RESULTS: The maximum median decrease in plasma HIV-1 RNA load from baseline ranged from 1.21 to 1.73 log(10) copies/mL. Plasma concentrations of BMS-626529 were not associated with an antiviral response, while low baseline inhibitory concentrations and the minimum and average steady-state BMS-626529 plasma concentrations, when adjusted by the baseline protein binding-adjusted 90% inhibitory concentration (inhibitory quotient), were linked with antiviral response. BMS-663068 was generally well tolerated. CONCLUSIONS: Administration of BMS-663068 for 8 days with or without ritonavir resulted in substantial declines in plasma HIV-1 RNA levels and was generally well tolerated. Longer-term clinical trials of BMS-663068 as part of combination antiretroviral therapy are warranted. Clinical Trials Registration.NCT01009814.

Determination of rifabutin dosing regimen when administered in combination with ritonavir-boosted atazanavir.

OBJECTIVES: Treatment of HIV/tuberculosis (TB) co-infected patients is complex due to drug-drug interactions for these chronic diseases. This study evaluates an intermittent dosing regimen for rifabutin when it is co-administered with ritonavir-boosted atazanavir. PATIENTS AND METHODS: A randomized, multiple-dose, parallel-group study was conducted in healthy subjects and these subjects received a daily dose of rifabutin 150 mg (n = 15, reference group) or a twice weekly dose with atazanavir 300 mg/ritonavir 100 mg once daily (n = 18, test group). Serial blood samples were collected at steady-state for pharmacokinetic analysis. Modelling and simulation techniques were utilized, integrating data across several healthy subject studies. This study is known as Study AI424-360 and is registered with ClinicalTrials.gov, number NCT00646776. RESULTS: The pharmacokinetic parameters (C(max), AUC(24avg) and C(min)) for rifabutin (149%, 48% and 40% increase, respectively) and 25-O-desacteyl rifabutin (6.77-, 9.90- and 10.45-fold increases, respectively) were both increased when rifabutin was co-administered with atazanavir/ritonavir than rifabutin 150 mg once daily alone. The study was stopped because subjects experienced more severe declines in neutrophil counts when rifabutin was given with atazanavir/ritonavir than alone. A post-hoc simulation analysis showed that when rifabutin 150 mg was given three times weekly with atazanavir/ritonavir, the average daily exposure of rifabutin was comparable to rifabutin 300 mg once daily, a dose necessary for reducing rifamycin resistance in HIV/TB co-infected patients. CONCLUSIONS: The benefits to HIV/TB co-infected patients receiving rifabutin 150 mg three times weekly or every other day may outweigh the risks of neutropenia observed here in non-HIV-infected subjects, provided that patients on combination therapy will be closely monitored for safety and tolerability.

Pharmacokinetics and safety of twice-daily atazanavir 300 mg and raltegravir 400 mg in healthy individuals.

BACKGROUND: Atazanavir plus raltegravir 300/400 mg twice daily is being explored as a ritonavir- and nucleoside-sparing treatment strategy. The pharmacokinetics and safety of this combination in healthy individuals were evaluated. METHODS: A total of 22 healthy individuals received raltegravir 400 mg on days 1-5, atazanavir 300 mg on days 6-12 and atazanavir plus raltegravir 300/400 mg on days 13-26, twice daily with a light meal. Serial blood samples were collected 12 h after the morning dose on days 5, 12 and 26; safety assessments, clinical laboratory data and serial electrocardiograms (ECGs) at 0, 2 and 6 h were obtained. RESULTS: Raltegravir coadministration reduced atazanavir geometric mean maximum plasma concentration (C(max)), area under the plasma concentration-time curve from 0 to 12 h post-dose (AUC(0-12)) and trough plasma concentration (C(min)) by 11%, 17% and 29%, respectively, compared with atazanavir alone. Geometric mean atazanavir C(min) was 817 ng/ml (range 250-1,550) with raltegravir coadministration. Atazanavir increased raltegravir geometric mean C(max), AUC(0-12) and C(min) by 39%, 54% and 48%, respectively. All adverse events were of mild or moderate intensity. Hyperbilirubinaemia and ECG PR increases with atazanavir were similar to those of atazanavir/ritonavir once daily. No corrected QT prolongations were noted. Mean QRS increase from baseline was 11.0 ms (range 2-25) after receiving atazanavir for 7 days; no further QRS increase was noted and no QRS interval was >120 ms with raltegravir coadministration. No ECG changes were observed with raltegravir alone. CONCLUSIONS: Coadministration of atazanavir and raltegravir 300/400 mg twice daily decreased atazanavir AUC(0-12) and C(min) relative to atazanavir alone, and increased AUC(0-12) of raltegravir relative to raltegravir alone. Atazanavir and raltegravir alone and coadministered appeared safe and well-tolerated.