Single-dose kinetics of nifedipine in rat plasma and brain.

Nifedipine concentrations in plasma and brain tissue of rats were assayed from 5 min to 4 h after an intravenous injection of 6 mg/kg body weight. Samples of rat plasma and homogenized brain tissue were extracted under sodium light with a dichloromethane-pentane mixture. Analyses were done by high-performance liquid chromatography on a reverse-phase C18 column with electrochemical detection. The peak concentration of nifedipine in brain obtained after 10 min was 37 micrograms/g wet weight tissue, the half-life was 75 min. Apparently, nifedipine can easily cross the blood-brain barrier in the rat.