Effect of Hydroxypropyl Methylcellulose and Ethyl Cellulose Content on Release Profile and Kinetics of Diltiazem HCl from Matrices

Purpose: To develop a oral controlled matrix drug delivery system for a highly water soluble drug, diltiazem HCl, and investigate its drug release mechanism. Method: Diltiazem HCl was chosen because of its high water solubility. Tablets containing the drug were prepared by direct compression method using different matrix ratios of ethyl cellulose (EC) and hydroxypropyl methylcellulose (HPMC). The formulations were evaluated in vitro for their dissolution characteristics over a period of 8 h. Drug release was analysed according to various release kinetic models. Results: The results showed that these polymers slowed down the release of diltiazem HCl from the matrices. In the presence of EC, increasing the concentration of HPMC decreased the release rate of diltiazem. Furthermore, incorporation of EC in tablets with HPMC as the matrix was found to control drug release. Kinetic analysis showed that drug release from three of the formulations was adequately described by zero order model. Conclusion: The formulations developed could potentially be used for controlled delivery of highly soluble drugs such as diltiazem HCl.