Single-Dose Interaction Study of the Arginine Vasopressin Type 1B Receptor Antagonist ABT-436 and Alcohol in Moderate Alcohol Drinkers.

BACKGROUND: ABT-436, a potent and selective arginine vasopressin (AVP) type 1B receptor (V1B ) antagonist, has previously demonstrated basal hypothalamic-pituitary-adrenal (HPA) axis attenuation in man. A V1B antagonist is hypothesized as an alcohol-dependent treatment based on the role of the V1B receptor in stress regulation and the finding that stress is a trigger for relapse in alcoholics. A V1B antagonist has shown favorable effects in rat models of alcohol dependence. A single-dose clinical study was conducted to assess the potential for pharmacokinetic or pharmacodynamic interaction between ABT-436 and alcohol. METHODS: Twenty moderate alcohol drinkers each received the 4 possible combinations of a single 1,000 mg ABT-436 dose (or matching placebo) and a single 0.5 g/kg alcohol dose (or placebo for alcohol) in a double-blind, randomized, 4-period crossover study. Plasma ABT-436 and blood alcohol levels were measured to assess pharmacokinetic interactions. A computerized cognitive test battery (CDR System), Bond-Lader Visual Analog Scales scales, and a postural stability test were used to measure the effects of alcohol and the potential interaction with ABT-436. The pharmacologic effect of ABT-436 was assessed by measuring serum cortisol. RESULTS: Neither ABT-436 nor alcohol affected the blood levels of the other. Alcohol reduced performance on 2 of 5 CDR System composite variables (power of attention, p = 0.002; quality of secondary episodic memory, p < 0.001), and decreased postural stability (p = 0.043). ABT-436 did not exacerbate those deleterious effects. ABT-436 reduced serum cortisol (p < 0.001), and alcohol did not significantly diminish this expected effect on the HPA axis. CONCLUSIONS: No pharmacokinetic or pharmacodynamic interaction between ABT-436 and alcohol was observed.

Dual effects of rifampin on the pharmacokinetics of atrasentan.

The effect of rifampin, a cytochrome P450 3A4 inducer, on the pharmacokinetics of atrasentan was assessed in 12 healthy male subjects in an open-label study. Single doses of atrasentan 10 mg were administered orally on days 1 and 12. Rifampin 600 mg was given once daily from days 4 through 14. On day 12, atrasentan and rifampin were administered simultaneously. Blood samples were collected before and during 72 hours after each atrasentan dose. On average, rifampin increased atrasentan peak plasma concentrations by 150% and reduced its terminal half-life by 77% (P<.05), without affecting the AUC or peak time of atrasentan. Rifampin may affect atrasentan pharmacokinetics by acting as both an inhibitor of organic anion transporting polypeptide-mediated hepatic uptake of atrasentan and an inducer of atrasentan metabolism. The effect of rifampin on atrasentan pharmacokinetics may depend on the time of rifampin administration relative to that of atrasentan.

Evaluation of the potential for pharmacokinetic interaction between fenofibrate and ezetimibe: A phase I, open-label, multiple-dose, three-period crossover study in healthy subjects.

OBJECTIVE: This study was conducted to evaluate the potential for pharmacokinetic interaction between fenofibrate and ezetimibe in healthy subjects. METHODS: This was a Phase I, open-label, multiple-dose,3-period crossover study conducted in healthy adult men and women. Subjects received fenofibrate 145 mg alone, fenofibrate 145 mg with ezetimibe 10 mg, and ezetimibe 10 mg alone for 10 consecutive days, in an order determined by computerized randomization schedule. Blood samples were collected for up to 24 hours after dosing on study day 1 and up to 120 hours after dosing on study day 10 for determination of plasma concentrations of fenofibric acid, unconjugated (free) ezetimibe, and total (conjugated and unconjugated) ezetimibe using validated high-performance liquid chromatography methods with mass-spectrometric detection. Ezetimibe glucuronide concentrations were estimated by subtracting free ezetimibe concentrations from total ezetimibe concentrations. RESULTS: Eighteen healthy adults (12 men, 6 women; 17 white, 1 black) were enrolled in the study. Their mean age was 43.4 years (range, 27-55 years), their mean weight 78.7 kg (range, 60-98 kg), and their mean height 174.9 cm (range, 156-194 cm). Coadministration of multiple doses of fenofibrate and ezetimibe produced no statistically significant effect on the pharmacokinetics of fenofibric acid but significantly increased exposures to total ezetimibe and ezetimibe glucuronide (P < 0.05). Using point estimates, co-administration of fenofibrate and ezetimibe increased AUC central values for total ezetimibe and ezetimibe glucuronide by 43% (90% CI, 29-59) and 49% (90% CI, 34-65), respectively. CONCLUSION: In these healthy volunteers, coadministration of multiple doses of fenofibrate and ezetimibe had no statistically significant effect on the pharmacokinetics of fenofibric acid but was associated with a significant increase in exposure to total ezetimibe and its metabolite ezetimibe glucuronide.

The effects of multiple doses of fenofibrate on the pharmacokinetics of pravastatin and its 3alpha-hydroxy isomeric metabolite.

Published data indicate that coadministration of multiple doses of the fibrate drug, gemfibrozil, led to a 202% increase in pravastatin systemic exposure (area under the plasma concentration-time curve, AUC). To evaluate the effects of another fibrate drug, fenofibrate, on the pharmacokinetics of pravastatin, 24 healthy subjects took pravastatin (40 mg once daily) on study days 1 to 15 and fenofibrate (160 mg once daily) on study days 6 to 15. Blood samples were collected for 24 hours after dosing on days 5, 6, and 15. Plasma concentrations of pravastatin and its active metabolite, 3alpha-hydroxy-iso-pravastatin, were measured, and pharmacokinetics was assessed. Safety assessments were based on adverse events, physical examinations, electrocardiogram results, vital signs, and clinical laboratory testing. Safety results were unremarkable. Coadministration of fenofibrate had modest effects on pravastatin and 3alpha-hydroxy-iso-pravastatin systemic exposures (AUC). Increases in pravastatin systemic exposures (19%-28%, on average) and 3alpha-hydroxy-iso-pravastatin systemic exposures (24%-39%, on average) were observed upon coadministration, but individual changes were variable. Pravastatin and 3alpha-hydroxy-iso-pravastatin systemic exposures were not statistically significantly different following the 1st and 10th doses of fenofibrate.

Pharmacokinetics and Safety of ABT-578, a Sirolimus (Rapamycin) Analogue, after Single Intravenous Bolus Injection in Healthy Male Volunteers.

OBJECTIVE: ABT-578, a tetrazole analogue of sirolimus (rapamycin), possesses anti-restenosis activity. The aim of this study was to assess the safety and pharmacokinetics of escalating single intravenous (IV) doses of ABT-578 in a phase 1, double-blind, randomised, placebo-controlled study. METHODS: Sixty adult healthy males were divided into five IV-dose groups of 100, 300, 500, 700 and 900mug. Doses were administered as IV bolus over 3 minutes, with eight subjects and four subjects receiving ABT-578 and placebo, respectively, in each dose group. Higher doses were administered after evaluating safety from the preceding lower doses. Blood concentrations of ABT-578 were sampled for 168 hours and measured using LC-MS/MS with a limit of quantification of 0.20 ng/mL. RESULTS: The pharmacokinetics of ABT-578 were essentially linear across the 100-900microg dose range as illustrated by the dose-proportional increases in concentration at 5 minutes (C(5)) after the end of infusion and area under the concentration-time curve (AUC). The mean half-life ranged between 26.0 and 40.2h over the studied doses and was not significantly different over the 300-900mug dose range. The mean clearance values ranged from 2.90 to 3.55 L/h. Single IV bolus doses up to 900mug of ABT-578 were well tolerated and no clinically significant changes in physical examination results, vital signs or laboratory test results were observed. CONCLUSION: It can be concluded that the pharmacokinetics of IV ABT-578 are dose-proportional over the 100-900mug dose range. Single IV bolus doses up to 900mug were well tolerated in healthy male subjects.

Bioavailability of lansoprazole granules administered in juice or soft food compared with the intact capsule formulation.

BACKGROUND: The ability to administer the contents of an encapsulated-dose formulation in liquids or soft foods without compromising drug bioavailability is highly desirable for patients who are unable to swallow or have difficulty swallowing. OBJECTIVE: The purpose of this study was to compare the bioavailability of lansoprazole granules administered in 2 types of juice and a soft food with that of the intact capsule administered with water. METHODS: Healthy adult volunteers were eligible for this single-center, Phase I, single-dose, randomized, open-label, 4-period crossover study. Subjects received the enteric-coated granular contents of a 30-mg lansoprazole capsule in 3 test regimens (in 180 mL of orange juice, 180 mL of tomato juice, or 1 tablespoon of strained pears, each followed by 180 mL of water) and 1 reference regimen (the 30-mg intact capsule with 180 mL of water). The regimens were rotated at > or = 6-day intervals so that each subject received all 4 regimens. Blood samples for pharmacokinetic analyses were obtained during the 12 hours after each regimen. RESULTS: Twenty healthy adult volunteers (10 men, 10 women; mean age, 36 years [range, 19-53 years]) completed this study. Bioavailability of the 3 test regimens was assessed using the two 1-sided tests procedure for mean maximum plasma concentration and area under the plasma concentration-time curve (AUC) from time 0 through the last measurable concentration and AUC from time 0 to infinity. These results were compared with that of the intact capsule. This comparison indicated that the 90% CIs for all 3 test regimens were within the acceptable bioequivalence range of 0.80 to 1.25. Lansoprazole was well tolerated, with most of the adverse events being mild. Headache was the most frequently reported adverse event. CONCLUSION: The results of this study indicate that the bioavailability of lansoprazole granules, when administered in orange juice, tomato juice, or a small amount of strained pears, was similar to that of the intact capsule in these healthy adult volunteers.