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%.