Psychopharmacology
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The effects of long-acting narcotic agonist preparations on the severe withdrawal syndrome following abrupt cessation of daily injections of codeine phosphate were studied in rats. Twelve hours after the last codeine injections, one injection of either a high or low dose of the zinc tannate salt of heroin, levo-alpha-acetylmethadol (LAAM) or hydromorphone in slow-release vehicle (SRV) was administered. Body weight, core temperature and hyperirritability scores (Teiger, 1974) were recorded every 6 h for the next 3 days. ⋯ All rats injected with either LAAM or hydromorphone zinc tannate exhibited prolonged marked hyperthermia, but the low, the high dose heroin groups and the SRV groups showed no significant differences in diurnal temperature patterns. Rats treated with the narcotic agonists were generally less irritable, as indicated by lower Teiger scores. These results indicate that a single injection of heroin, LAAM or hydromorphone zinc tannate can ameliorate the characteristic and intense signs of abstinence following withdrawal from codeine.