Abstract
Experiments were carried out in guinea pigs passively sensitized with rabbit antiovalbumin serum in doses producing a moderate or intense sensitivity. The effect of promethazine in different doses on the early and delayed anaphylactic death was investigated. Large doses of promethazine (25 mg/kg) decrease significantly the total anaphylactic lethality, protecting the animals both from early and delayed death. This effect is due essentially to the interference of the non-histaminic mechanisms.