title: Long acting delivery systems for narcotic antagonists II: release rates of naltrexone from poly(lactic acid) composites.
abstract: Parallel in vitro and in vivo release rates of tritiated naltrexone from poly(lactic acid) composites were studied. The in vitro release of naltrexone was 67% of the dose over a 35-day test period, while the in vivo release was only 24% within 70 days. Apparently, an exchange of the tritium for the hydrogen of the body water takes place, indicating that urinary excretion radioactivity is not a reliable measure for estimating the naltrexone released. Naltrexone-poly(lactic acid) composites showed effective blocking action to morphine in rats (24 days), dogs (29 days), monkeys (20 days), and mice (21 days).
mesh_terms: D000818:Animals; D003496:Cyclazocine / Q000494:pharmacology; D003521:Cyclopropanes / Q000652:urine; D003692:Delayed-Action Preparations; D004285:Dogs; D007474:Ion Exchange; D007773:Lactates; D008253:Macaca mulatta; D008297:Male; D051379:Mice; D009020:Morphine / Q000037:antagonists & inhibitors; D009270:Naloxone / Q000031:analogs & derivatives* / Q000652:urine; D009292:Narcotic Antagonists / Q000494:pharmacology / Q000652:urine; D011108:Polymers; D051381:Rats; D012018:Reflex / Q000187:drug effects; D013997:Time Factors; D014316:Tritium
chemical_list: D003521:Cyclopropanes; D003692:Delayed-Action Preparations; D007773:Lactates; D009292:Narcotic Antagonists; D011108:Polymers; D014316:Tritium; D009270:Naloxone; D009020:Morphine; D003496:Cyclazocine