The acute toxicity of ephedrine.

Abstract

In our preliminary report, 1 , 2 mention was made concerning the toxicity of ephedrine in rats and rabbits. As the drug is possibly of clinical importance in the treatment of asthma and hypotension as demonstrated in the Peking Union Medical College Hospital, it is thought desirable to study its toxicity more in detail.

Ephedrine sulphate was used in all our experiments.

In frogs, the M.L.D. by injection into the anterior lymph sac varies from 530 to 680 mg. per kilo of body weight. The animal shows weakness in the legs half an hour after the injection of such a dose, and dies in 2 to 3 hours without any noticeable convulsions.

Of the mammals investigated, the white rat appears to be most tolerant to the drug. By intravenous injection, the M.L.D. in mg. per kilo of body weight in rabbits is 66-70, in dogs 70, in cats 75, and in white rats 135-140. It appears that animals weighing over a kilo have their M.L.D. approximating 70 mg. per kilo. Death is almost immediate and follows clonic convulsions. If the chest is opened when the animal is apparently dead, the heart is seen either in fibrillation or in incomplete block. The skin and the mucous membrane do not appear to be blanched. In anesthetised animals, the M.L.D. causes an immlediate and permanent fall in blood pressure to 10-15 mm. Hg, accompanied by a tremendous decrease of intestinal and kidney volumes. The respiratory movements may persist for a short time after the blood pressure has reached the lowest level. The fall of pressure is not prevented by artificial respiration after the destruction of the brain and the cord. Death is therefore least likely due to the failure of the respiratory center.