Controlled Release of the Nimodipine-Loaded Self-Microemulsion Osmotic Pump Capsules: Development and Characterization

The present study was intended to develop a controlled released osmotic pump capsule based on Nimodipine (NM)-loaded self-microemulsifying drug delivery systems (SMEDDSs) in order to improve the low oral bioavailability of NM. To optimize the NM-loaded SMEDDS composition, the experiments of NM solubility in different oils, the pseudo-ternary phase diagram experiments and the different drug loading experiments were conducted in the preliminary screening studies. Controlled release of NM required an osmotic pump capsule comprising a coated semi-permeable capsule shell, plasticizer, and pore-forming agent. NM release follows zero-order kinetics after oral administration. Polyethylene glycol content, used as a pore-forming agent, coating mass, and drug release orifice size were key factors affecting drug release behavior according to the single methods and were optimized through response surface methodology. The NM-loaded SMEDDS droplet size and the 1 H NMR mass spectrogram of the novel capsule were determined. The droplet size of the reconstituted microemulsion was 39.9 nm and 1 H NMR analysis showed NM dissolution in the microemulsion. The dissolution test performed on three batches of NM-SMEDDS capsules—prepared using optimal preparation methods—indicated the capsule to deliver a qualified drug delivery with a zero-order release rate. The results demonstrated that NM-loaded SMEDDSs were successfully developed and displayed a qualified release rate in vitro .