THE EFFECTS OF ANALGESIC AGENTS ON BARBITURATE RESPONSES IN MICE

Studies were completed on the effects of several dl -phenylhexamethylenimine derivatives, meperidine hydrochloride, morphine sulphate and dl -methadone hydrochloride on the tolerance of the side position induced in mice by hexobarbital sodium and pentobarbital sodium. Premedication with the analgesic dose-50 or twice this dose 15 minutes prior to an effective dose of the barbiturates prolonged the effects of the latter. Similarly, the analgesic agents converted a sub-effective dose of pentobarbital to an effective one. When premedication with the analgesic agents was 24 hours prior to the barbiturates, the effects of the latter were shortened, except after morphine which tended to prolong the recovery time. Chronic administration of dl -4-carbethoxy-1-methyl-4-phenylhexamethylenimine hydrochloride (Wy-401) or meperidine hydrochloride for several weeks did not significantly influence the responses to barbiturates.