Formulation and evaluation of floating and sustained release drug delivery system of diltiazem HCl

Abstract

Oral formulations have a substantial place among the various dosage forms because of the ease of administration, patient compliance, and flexibility in formulation. Mostly the conventional oral drug delivery systems show inadequate bioavailability due to fast gastric emptying time. Floating drug delivery systems can remain in the gastric region for several hours and therefore prolong the gastric residence time of drugs and improve drug bioavailability. Diltiazem hydrochloride (DTZ) is a calcium channel blocker with low half-life time which is used for the treatment of hypertension and angina. In this study a bilayer gastro-retentive floating system of DTZ was prepared to control the release rate of the drug.

Aim of the study The aim of this study is to develop an innovative floating controlled release formulation of diltiazem to achieve persistent plasma concentration of the drug, and therefore reducing the frequency and side effects of the drug and improve patient compliance.

Methods and Materials The tablets were prepared by direct compression technique, using polymers such as hydroxypropylmethyl cellulose (HPMC), Carbopol, 934, Psyllium, Ethyl cellulose (14cP) and Tragacanth alone or in combination, and other standard excipients. Sodium bicarbonate was incorporated as a gas-generating agent. Floating properties, drug release and release kinetic were assessed.

Results The results of buoyancy and release studies showed that a combination of HPMC, tragacanth, DTZ and sodium bicarbonate favors the preparation of the outer layer of bilayer floating controlled release DTZ tablets. The linear regression analysis and model fitting showed that the optimized formulation followed linear probability model.

Conclusion It was possible to control the release of highly soluble DTZ by combining the floating and bilayered tablet tools. By altering the amount of components in formulations, the characterization of tablets could be controlled. This system can probably be used for controlling the release of other highly water-soluble drugs.