Modification of Anaphylaxis by Benadryl.

Abstract

Summary The intravenous injection of Benadryl (10 mg per kilo) into horse serum sensitized dogs, prior to the reinjection of horse serum, reduces the severity of anaphylactic shock in these animals, there being no deaths in 22 animals as against 9 deaths in 26 controls. As Benadryl has a similar modifying effect upon the shock induced by the injection of histamine, the results of these experiments are consistent with the theory that histamine plays a significant role in anaphylaxis in dogs. Unfortunately, Benadryl merely reduces, but does not obliterate, the vasodepressor effects of histamine and thus the present experiments with Benadryl do not permit conclusions as to whether histamine is or is not the sole vasodepressor factor in anaphylaxis in the dog.