Development of nifedipine-loaded coated gelatin microcapsule as a long acting oral delivery.

To develop the long acting nifedipine oral delivery with enhanced bioavailability, nifedipine-loaded gelatin microcapsule containing nifedipine and ethanol in gelatin shell was prepared using a spray-dryer, and then coated microcapsule was prepared by coating the gelatin microcapsule with Eudragit acrylic resin. The dissolution test and the bioavailability of the coated microcapsule in rats were evaluated compared to nifedipine powder. The amount of nifedipine dissolved from gelatin microcapsule for 30 min increased about 5-fold compared to nifedipine powder in pH 1.2 simulated gastric fluid. Nifedipine released from the coated microcapsule was retarded in pH 1.2 simulated gastric fluid compared with that from gelatin microcapsule. Furthermore, the coated gelatin microcapsule maintained the plasma level of nifedipine over 4 h and gave significantly higher AUC of nifedipine than nifedipine powder. Thus, the Eudragit-coated gelatin microcapsule, which could maintain the plasma level of nifedipine over a longer period without the initial burst-out plasma concentration, is a preferable delivery system for poorly water-soluble nifedipine.