Studies on the mechanism of action of miconazole: effect of miconazole on respiration and cell permeability of Candida albicans.

The antifungal drug, miconazole nitrate, inhibits the growth of several species of Candida. Candida albicans, one of the pathogenic species, was totally inhibited at a concentration of approximately 10 mug/ml. Endogenous respiration was unaffected by the drug at a concentration as high as 100 mug/ml, whereas exogenous respiration was markedly sensitive and inhibited to an extent of 85%. The permeability of the cell membrane was changed as evidenced by the leakage of 260-nm absorbing materials, amino acids, proteins, and inorganic cations. The results we present clearly show that the drug alters the cellular permeability, and thus the exogenous respiration becomes sensitive to the drug.