LC separation and induced fluorometric detection of rivastatin in blood plasma

An LC procedure suitable for quantitative analysis of pg ml-1 concentrations of the HMG-CoA reductase inhibitor rivastatin in blood plasma was developed. The procedure involves an extraction step, chromatography on an ODS column, and fluorometric detection of a post-column photolytic decomposition product that was isolated and identified. The achieved quantitation limit (25 pg ml-1) facilitated analysis of relatively low rivastatin concentrations in plasma that were observed after 100-300 micrograms oral doses of rivastatin. At 25 pg ml-1 concentration the RSD ranged from 3.6 to 13.5% and mean deviation from the nominal value was 8.0%; at 8 ng ml-1 the RSD range was 0.7-3.6% while the mean deviation was -1.8%. The concentrations obtained with the LC procedure were compared to the concentrations obtained with a specific but less sensitive capillary GC method and a radioimmunoassay (RIA) procedure. Concentrations obtained with the HPLC and GC procedures agreed within experimental error; the RIA concentrations were about 30% higher.