COMPARISON OF BIOAVAILABILITY BETWEEN NIMOTOP AND NIMODIPINE TABLET

A new analytical method was established for determining plasma level of nimodipine using HPLC and its application to determine the bioavailability of nimodipine. Experiments were performed on a Waters Model Baseline 810 System instrument. A 3.9 mm×200 mm stainless steel column was packed with YWG-C₁₈ (10 μm) as the stationary phase. The mobile phase was a mixture solution of methanol—water (60/40, v/v) with 1.00 ml·min^-1 at 35℃. The detector was set at 358 nm. The plasma samples were extracted with ether—n-hexane (1∶1). Calibration curve was linear (γ=0.9999) in the concentration range of 5～300 ng·ml^-1. The withinday and betweenday precision (RSD) were less than 3% and 5%, respectively, with average recoveries of 97.67%～102.3%.The study on bioavailability of nimodipine between tablet A (made in China) and nimotop (Bayer, Germany) was carried out in 8 volunteers at the oral dose of 120 mg by cross-over method. Two-compartment open model was suitable for describing the disposition of nimodipine. The main pharmacokinetic parameters were shown in Tab 1 and mean plasma concentration-time curve of nimodipine was shown in Fig 1. The results indicate that tablet A exhibited a lower bioavailability (relative to nimotop). We suggest that the product tablet A must be improved in formula and technology.