title: Prolonged blockade of opioid effect with oral nalmefene.
abstract: In a placebo-controlled, double-blind study we evaluated the ability of a single 50 mg oral dose of nalmefene to block the effects of intravenous opioid challenge (2 micrograms/kg fentanyl). Fentanyl-induced respiratory depression (CO2 responsiveness), analgesia (tourniquet ischemia), and subjective effects were totally blocked for 48 hours and showed only minimal breakthrough 72 hours after nalmefene. Plasma concentration-time data for nalmefene indicate good oral bioavailability and a prolonged terminal elimination phase (mean t1/2 11.1 hours). These findings suggest that nalmefene could provide prolonged effectiveness in limiting emergence of opioid effects during addiction therapy.
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000698:Analgesia; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D005283:Fentanyl / Q000494:pharmacology; D006801:Humans; D008297:Male; D009271:Naltrexone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects; D013997:Time Factors
chemical_list: D009292:Narcotic Antagonists; D009271:Naltrexone; C038981:nalmefene; D005283:Fentanyl