Stability and in vitro activity of nystatin and its γ-cyclodextrin complex against Candida albicans

Abstract γ-Cyclodextrin (γ-CD) was found to form an inclusion complex with nystatin. In the presence of γ-CD, cells of Candida albicans absorbed less nystatin than in its absence. The γ-CD/nystatin complex had no or insignificant antimicrobial activity. Upon diffusion into a γ-CD-free medium the antibiotic was released from the complex and inhibited growth of the test organism. The stability of nystatin and the γ-CD complex was studied using both a microbiological and a spectrophotometric assay. The stability of nystatin in aqueous preparations was improved by γ-CD complexation. Degradation of pure nystatin did not follow first-order kinetics. The loss of antimycotic potency was more rapid than the decrease in concentration calculated from the spectrophotometric data for the pure antibiotic as well as its γ-CD inclusion complex.