Synergistic effects of chlorpromazine and perphenazine on several chemotherapeutic agents. I. General profile of the effects measured by the filter paper strip-agar diffusion method with Escherichia coli and Pseudomonas aeruginosa.

The combination effects of chlorpromazine (CPZ) and periphenazine (PPZ) with beta-lactam antibiotics (ampicillin, carbenicillin, cefazolin) and nalidixic acid group compounds (nalidixic acid, piromidic acid and pipemidic acid) have been estimated to be synergistic by the filter paper strip-agar diffusion method (Dye's method) with Escherichia coli and Pseudomonas aeruginosa as test organisms. The observed synergism might be associated with their inhibition of various enzymes including ATPase and DNAase as well as with their specific binding to DNA. Similar synergistic effects of CPZ and PPZ have been shown by the broth dilution method. Based on these findings, it seems to be a fascinating project to devise a new phenothiazine drug without influence in mental disease that will have a greater measure of synergistic effect when combined with the above-studied antibacterial agents.