Determination of acyclovir by ultrafiltration and high-performance liquid chromatography

A simple, sensitive and rapid high-performance liquid chromatographic (HPLC) procedure to determine total serum acyclovir concentrations is described. The assay involves a heat inactivation step at 56 degrees C to prevent risk of infection, ultrafiltration as a pretreatment step prior to ion-pair reversed-phase liquid chromatography using guanosine as internal standard, and ultraviolet detection at 254 nm. This method has excellent recovery (97-100%), linearity (0.5-100 mg/l) and precision (1.2-8.0% coefficient of variation). The detection limit is 50 micrograms/l. The assay proved to be suitable for therapeutic drug monitoring of acyclovir.