In vitro and in vivo evaluation of a novel diltiazem hydrochloride polydispersity sustained-release system

Objective: To microencapsulate diltiazem hydrochloride (DH) drug-resin to obtain obvious sustained release effect in vitro and in vivo. Methods: The drug-resinates were made by bath method. The drug-resinates microcapsules were prepared with the ratio of the concentration of coating materials being 1% and the ratio of drug-resin complexes to coating materials being 10: 1 by emulsion-solvent diffusion method. The pharmacokinetic of the sustained-release DH microspheres in beagle dogs was carried out. Results: The microencapsulated ion-exchange resin beads containing DH showed sustained-release characteristics for 12 h and exhibited complete release. The pharmacokinetics parameters of DH sustained-release microspheres and reference tablet was AUC0-24 (ng.h.mL(-1)) 836.3 and 857.3, C-max (ng.mL(-1)) 85.4 and 135.2, T-max (h) 4.7 and 1.2. Conclusion: The mononucleated microencapsulated ion-exchange resin beads showed obvious sustained release character in vitro. The pharmacokinetic of the DH microspheres showed that the test dosage forms were bioequivalent with reference dosage form and had an obviously sustained release effect in vivo.