[Comparison of bioavailability between nimotop and nimodipine tablet]

Abstract

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 x 200 mm stainless steel column was packed with YWG-C18(10 microns) 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 degrees C. The detector was set at 358 nm. The plasma samples were extracted with ether--n-hexane (1:1). Calibration curve was linear (gamma = 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 numodipine 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.