[On the acute toxicity of labetalol (AH-5158), a combined alpha-and-beta-adrenoceptor-blocking agent (author's transl)].

Acute toxicity studies in labetalol were performed using mice, rats and rabbits, An oral administration of labetalol produced an increase in salivary secretion due to local irritation. Death followed convulsions by large doses of labetalol. Pathological examinations suggested that the cause of death by labetalol was circulatory disturbances due to the damage of heart muscles and a subsequent respiratory paralysis. Parenteral LD50 showed almost the same values among mice (50 mg/kg iv, 117 mg/kg ip), rats (66 mg/kg iv, 115 mg/kg ip) and rabbits (43 mg/kg iv). However, species difference was seen in oral LD50 values which were enormously large as compared with iv LD50 values.