Effect of phenobarbital on the toxicity of several organophosphorus insecticides

Abstract

The toxicity of the organophosphorus insecticides dimethoate, O,O-dimethyl S-( N-methylcarbamoylmethyl) phosphorodithioate; phosphamidon, dimethyl phosphate, ester with 2-chloro- N,N-diethyl-3-hydroxy-crotonamide; Bidrin, dimethyl phosphate, ester with cis-3-hydroxy- N,N-dimethylcrotonamide; and their N-dealkylated derivatives was compared in mice. The toxicity of dimethoate to mice was increased from an LD 50 of 198 mg/kg to 58.5 mg/kg by pretreatment of mice for 3 days with 75 mg/kg of sodium phenobarbital per day. The toxicity of phosphamidon, Bidrin, and their N-dealkylated derivatives was decreased by approximately one-half by the same pretreatment with phenobarbital.