Effects of promethazine on hemorrhagic shock in the dog

The effects of pre- and post-treatment with promethazine, an antihistamine, in hemorrhage-shocked dogs were investigated. Survival to 6 hours was enhanced in the dogs given (IM administration) the H1-receptor antagonist at 1 hour before hemorrhage was induced when compared with survivals of saline-treated control dogs (3 of 5 dogs vs 1 of 5 dogs). Furthermore, 4 of 5 dogs given (IV administration) promethazine at 30 minutes after the initial hemorrhage survived. Promethazine treatment by either route increased mean arterial pressure among surviving dogs throughout the 6-hour experimental period.