Development of an RP-HPLC-UV Method for Simultaneous Detection of Nimodipine and its Metabolite in Cerebrospinal Fluid of Rat

A rapid, simple and reproducible HPLC method was developed and validated for the analysis of nimodipine (NM) and/or its metabolite, oxidized nimodipine (OX-NM) in rat cerebrospinal fluid (CSF) and artificial CSF. The NM and OX-NM were eluted in less than 10 min with no interferences from the endogenous CSF peaks. Analysis was carried out on a Eurospher Performance (RP-C18, 250 × 4.6 mm) column and UV detection at 236 nm. The mobile phase consisted of acetonitrile and water (70:30 v/v, respectively) with a flow rate of 1 mL/min. Limit of detection was 0.1 μg/mL for OX-NM. The calibration curve was linear over the concentration range of 0.5-10 µg/mL and analytical recovery was more than 95%. The coefficients of variation for intra-day and inter-day assays were less than 5%.