Effects of glutathione and phenobarbital on the toxicity of codeinone

The ability of sulfhydryl compounds to provide protection against the acute toxicity of codeinone, a toxic metabolite of codeine, was investigated in mice. Subcutaneous administration of codeinone produced a slight reduction in hepatic glutathione concentration. Pretreatment of the mice with glutathione or cysteine significantly increased the survival rate for mice given a lethal dose of codeinone (10 mg/kg). The lethality of codeine was lowered by naloxone, whereas that of codeinone was not blocked by naloxone. The strychnine-like convulsant action of codeinone could be prevented by phenobarbital pretreatment. Glutathione pretreatment reduced the amounts of radioactivity in tissues of mice injected with [N-methyl-³H]codeinone. A possible explanation for these observations is that glutathione reacts in vivo with codeinone and plays a role as a scavenger of this compound. This assumption is supported by the observation that codeinone reacts non-enzymatically with glutathione under physiological conditions.