nystatin-a1 and acetonitrile

A reliable reversed-phase high-performance liquid chromatographic method was developed for the determination of liposomal nystatin in plasma. Nystatin is extracted by 1:2 (v/v) liquid-liquid extraction with methanol. Separation is achieved by HPLC after direct injection on a muBondapak C18 analytical column with a mobile phase composed of 10 mM sodium phosphate, 1 mM EDTA, 30% methanol and 30% acetonitrile adjusted to pH 6. Detection is by ultraviolet absorbance at 305 nm. Quantitation is based on the sum of the peak area concentration of the two major isomers of nystatin, which elute at 7.5-8.5 and 9.5-10.5 min. The assay was linear over the concentration range of 0.05 to 50 microg/ml. The lower limit of quantitation was 0.05 microg/ml, sufficient for investigating the plasma pharmacokinetics of liposomal nystatin in preclinical studies. Accuracies and intra- and inter-day precision showed good reproducibility. With minor modifications, this method also was used for assaying nystatin in various non-plasma body fluids and tissues.

Topics: Acetonitriles; Animals; Antifungal Agents; Centrifugation; Chromatography, High Pressure Liquid; Drug Stability; Edetic Acid; Hydrogen-Ion Concentration; Liposomes; Methanol; Nystatin; Phosphates; Rabbits; Reproducibility of Results; Sensitivity and Specificity; Tissue Distribution