An automated blood sampling system to measure lovastatin level in plasma and faeces

The aim of this study was to develop an automated sampling method to measure lovastatin in a conscious and freely moving rat. The blood samples were collected by means of the automated blood sampling system DR-II and the faecal samples were collected using a metabolic cage. The concentration of lovastatin was determined by a reversed-phase liquid chromatographic system with a UV absorbance detector. The mobile phase contained acetonitrile and 10 mM NaH₂PO₄ in the proportions 60:40 (v/ v) with a flow-rate of 1 mL/min. The calibration curve was linear in concentration ranges of 0.05-100 and 0.1-100 μg/ mL for lovastatin in blood and faecal samples, respectively. Following pharmacokinetic analysis, we identified that the maximum plasma concentration was around 1.18 ± 0.08 μg/mL at concentration peak time 120 min and almost 78% of loading dose was accumulated in the faeces within 48 h after lovastatin administration (500 mg/kg, p.o.).