Drug interaction of promethazine & other non-conventional antimicrobial chemotherapeutic agents

The antihistamine compound promethazine (Pz) showed significant antibacterial action when tested against 124 strains of aerobic and 13 strains of anaerobic bacteria belonging to both Gram positive and Gram negative genera. The range of MIC (micrograms/ml) of Pz varied between 50 and 200 micrograms/ml among most of the test organisms. Six Pz-sensitive strains were found to be simultaneously sensitive to similar non-conventional antimicrobics, e.g., methdilazine, bromodiphenhydramine, diphenhydramine, methyl-DOPA, promazine and the antibiotic augmentin. A high degree of synergism was observed in vitro when Pz was used in combination with methdilazine and bromodiphenhydramine.