Interaction between Bordetella pertussis vaccine and chlorpromazine in mouse experiments.

In acute toxicity experiments the mortality of mice pretreated with Bordetella pertussis vaccine increased on the first day following chlorpromazine (CPZ) treatment, compared to control animals treated with CPZ alone. Initially, the increased drug sensitivity observed after combined treatment was attributed to summation of the toxic effects. However, the cumulation of mortality did not cease on the following days, furthermore, an increase of bacterial translocation was observed on days 6 and 7, i.e. when the lymphocytosis, splenic hypertrophy and shrinkage of thymus-changes consequent to the vaccination-were at their maximum levels. On the basis of all these and on literary data it is supposed that the early cumulation of deaths after combined treatment may be in connection with an interaction between the two agents and that the side-effects following vaccination of humans may be induced by undesirable pharmacological interactions.