PREPARATION AND IN-VITRO DISSOLUTION PROFILE OF DUAL POLYMER (EUDRAGIT(TM) RS100 AND RL100) MICROPARTICLES OF DILTIAZEM HYDROCHLORIDE

A microparticulate dosage form for a highly soluble drug, diltiazem hy drochloride, was formulated with Eudragit RS100 and RL100 using a nove l dual polymer technique. A mixture of diltiazem with Eudragit RS100 ( low water permeability) in acetone was coacervated into soft polymer m icrodrops, following which a mixture of diltiazem and RL100 (high wate r permeability) was added to produce microparticles consisting of both polymers with diltiazem dispersed in the matrix. A second formulation was developed using the same method except using Eudragit RS100 for b oth steps. For a comparative study, diltiazem, Eudrait RS100 and RL100 were combined together in a single matrix and formulated into micropa rticles. In vitro drug release profiles using USP paddle dissolution a pparatus 2 revealed that dual polymer matrix microparticles containing Eudragit RS100 in the inner and Eudragit RL100 in the outer core exhi bit a suitable release profile with an initial release of the drug fol lowed by a plateau level for the test period of 5 h. Differential scan ning calorimetric analysis showed no interaction of the drug with the polymers.