Acute lethality of D- and L-ethionine in Swiss mice

The acute, 7-day LD50 in Swiss mice of D-ethionine administered intraperitoneally, was determined as 185 mg/kg with 95% confidence limits of 163 and 210 mg/kg. L-ethionine, the stereoisomer, which is more potent in inhibiting liver RNA synthesis, was not lethal at 2500 mg/kg. This acute toxicity of D-ethionine was suppressed by L-methionine and adenine. Blood accumulation in the thoracic cavity and pericardium was the probable cause of death.