Preparation of sustained-release nitrendipine microspheres with a solid dispersed structure in liquid system

AimTo prepare the sustained-release nitrendipine microspheres with a solid dispersed structure in liquid system. MethodsThe sustained-release nitrendipine microspheres with a solid dispersed structure was prepared in liquid system by combining spherical crystallization technique and solvent deposition method in one step. The resultant microspheres were evaluated for the recovery, micromeritc properties, incorporation efficiency. The factors of effect on the formation and the release rate of microspheres were also investigated. Results The recovery of microspheres (280-900 μm) was more than 70% and the bulk density was around 0.7 kg·L^-1. The incorporation efficiency always exceeded 95%. The formation of microspheres was mainly affected by the amount of bridging liquid and the emulsifying agents in poor solvent. The release rate of nitrendipine from the microspheres could be controlled as desired by adjusting the ratio of talc to Eudragit RS PO in the formulation. ConclusionThe presented method was suitable for preparing sustained-release microspheres of a water insoluble drug.