The clinical pharmacology of naltrexone: pharmacology and pharmacodynamics.

摘要: The time-action of opiate antagonist activity naltrexone was evaluated in detoxified ex-opiate addicts, using 25 mg intravenous heroin challenges. A 100 dose provided 96% blockade at 24 hr, 86.5% 48 hr and 46.6% 72 hr. Following oral administration, rapidly completely absorbed. Peak levels its major metabolite 6 beta-naltrexol were reached 1 after the dose. high plasma concentrations only drug administration indicate a rapid biotransformation process, converting large fraction to less active metabolites. Over 70% excreted urine than 0.5% feces. No change observed rate disposition during chronic dosing vs. acute study, indicating no metabolic induction. achievement steady state eliminates need stepwise induction beginning treatment.