Liquid chromatographic assay for simultaneous determination of abacavir and mycophenolic acid in human plasma using dual spectrophotometric detection

A combined bio-analytical assay for abacavir, a reversed transcriptase inhibitor, and mycophenolic acid (MPA), based on reversed-phase liquid chromatography and both ultraviolet (UV) absorption and fluorescence detection, is reported. Both analytes are extracted from plasma with acetonitrile. After centrifugation, evaporation of the supernatant and reconstitution in water, the sample is injected into the chromatograph. Abacavir is detected using UV detection at 285 nm and MPA spectrofluorometrically at 345 and 430 nm for excitation and emission, respectively. The method has been validated in the 80-2000 ng/ml range for abacavir and in the 10-10,000 ng/ml range for MPA for 200-microl plasma samples. The lower limits of quantification are 80 and 10 ng/ml for abacavir and MPA, respectively. Precisions and accuracies are < or = 8% in the valid concentration ranges of both analytes.