, Volume 103, Issue 2, pp 91–94 | Cite as

Requirement for nonprotonated drug molecules in the direct lethal action of miconazole against Candida albicans

  • William H. Beggs


At ≥10−5 M, miconazole (MCZ) can exert a direct physicochemical cell-damaging lethal action against logarithmic phase yeasts of Candida albicans. The imidazole moiety of MCZ has a pKa ∼ 6.5. Thus, in media of pH >6.5 most drug molecules are nonprotonated (MCZ∘). Conversely, at pH < 6.5 the majority are protonated and carry a positive charge (MCZH+). Our earlier work suggesting that MCZ∘ is required for direct lethal action was tested further. In support of such a requirement, we established a minimal lethal concentration of MCZ∘ (i.e. 5×10−6 M) that was relatively independent of pH, MCZ concentration, and MCZ∘∶MCZH+ ratio.

Key words

antifungal imidazoles miconazole Candida albicans 


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Copyright information

© Kluwer Academic Publishers 1988

Authors and Affiliations

  • William H. Beggs
    • 1
  1. 1.General Medical Research ServiceVeterans Administration Medical CenterMinneapolisUSA

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