Studies on the antimicrobial potential of the cardiovascular drug lacidipine

The cardiovascular drug lacidipine was screened in vitro for possible antibacterial activity with respect to 389 Gram-positive and Gram-negative bacterial strains. It was noticed that most bacteria (233) failed to grow at 50-200 μg/mL concentrations of the drug. Some strains were inhibited at even lower concentrations. The bacteria could be arranged according to their decreasing order of sensitivity as follows: Staphylococcus aureus, Vibrio cholerae, Salmonella spp., Shigellae, Escherichia coli, Bacillus spp., Klebsiellae and Pseudomonas spp. Lacidipine was found to be bacteriostatic in nature against S. aureus and V. cholerae. When administered to Swiss strain of white mice at doses of 30 and 60 μg/mouse, lacidipine significantly protected the animals challenged with 50 MLD of S. typhimurium NCTC 74. According to the chi-square test, the in vivo data were highly significant (p<0.001). The multifunctional nature of most medicinal agents has proved more to be the rule rather than the exception. Understanding this concept allowed scientists to investigate the antimicrobial properties of many drugs not pharmacologically classified as antimicrobial. Positive results were obtained for many drugs falling almost invariably under one of the following groups, namely psychotropics, neuroleptics, local anaesthetics, antihypertensives, antihistaminics, cardiovascular and antiinflammatory agents. Notable amongst them are the psychotropic chlorpromazine, the antihistamines bromodiphenhydramine and diphenhydramine, methdilazine, promethazine and trimeprazine, the tranquilizer promazine, the antihypertensives propranolol and methyl-DOPA, the local anesthetics procaine and lignocaine, the antiinflamniatory agent diclofenac, the neuroleptic phenothiazines trifluoperazine and fluphenazine, the cardiovascular agent amlodipine and oxyfedrine, and the antispasmodic compound dicyclomine. All these agents showing antimicrobial function were grouped together and termed as "non-antibiotics". Here we screened the cardiovascular drug lacidipine for its antibacterial activity.