Lethality of the morphinan isomers levorphanol and dextrorphan.
Significantly different (P<0.05) LD(50) values were found in Swiss-Webster mice for levorphanol (73 mg/kg, i.p.) and dextrorphan (120 mg/kg, i.p.). A subcutaneous injection of naloxone 15 min before challenge prevented the lethal effect of an LD(98) of levorphanol, with ED(50) value of 1.36 mg/kg. Naloxone, in doses from 2 to 100 mg/kg, did not prevent death caused by 150 mg/kg of either dextrorphan or levorphanol. Levorphanol was lethal for mice pretreated with 10 mg/kg of naloxone, a dose sufficient to block opiate-specific lethal effects, but the LD(50) value was 109 mg/kg, in contrast to 73 mg/kg in the absence of naloxone. By the criteria of stereospecificity and naloxone blockade, levorphanol-induced mortality in mice is a typical opiate effect in the lower of the two dose ranges studied. At higher doses of levorphanol a non-specific effect supervenes, with an LD(50) value virtually the same as that of dextrorphan.
D000818:Animals; D007279:Injections, Subcutaneous; D007536:Isomerism; D007928:Lethal Dose 50; D007981:Levorphanol / Q000633:toxicity*; D008297:Male; D051379:Mice; D009019:Morphinans / Q000633:toxicity*; D009270:Naloxone / Q000494:pharmacology
D009019:Morphinans; D007981:Levorphanol; D009270:Naloxone