Content area
Full Text
ABSTRACT:
The aim of the presented work was formulation and in-vitro evaluation of in-lay tablets containing telmisartan as sustained release outer core and hydrochlorothiazide as immediate release inner core using HPMC and co - polymer carbopol 71G. Tablets were evaluated via various quality control tests and in-vitro drug release studies. Drug release study was carried out hydrochloric acid buffer of pH 1.2 (0.1N) using USP paddle apparatus. The validated HPLC-UV method was applied to determine the amount of drugs released at different time intervals. The mechanism of drug release through polymeric network was established. Prepared tablets showed extended sustain release of telmisartan over a period of 20 h and hydrochlorothiazide as immediate release within 30 min.
KEYWORDS: In-lay tablet, telmisartan, hydrochlorothiazide, sustained release, immediate release.
INTRODUCTION:
Formulation of in-lay tablet has been used in the recent years for the development of controlled release formulation to obtain the desired results. The in-lay tablet is the type of multiple compression tablets and is similar to layered tablets. It is formulated by core tablet, which is surrounded by outer layer of drug. During the preparation, the bottom of the die cavity is filled with outer layer material and core is placed upon it. By applying the compression force, the outer layer material forms the strongly compressed layer. [1, 2] Simple lines diagram for the preparation of in-lay tablets its top view and cross section is represented in Figure 1. In-lay tablet is suitable for predetermined release of two drugs in combination in which one core is formulated as sustained release and second core is designed as immediate release.
The drugs are dispersed uniformly in their respective parts. After ingestion, matrixed tablets undergo hydration in contact with water. The polymeric matrix absorbs the water and swells. Finally the drug diffusion occurs by erosion of outer surface of tablet matrix. Telmisartan is water insoluble antihypertensive drug used in the treatment of hypertension and belongs to a group of angiotensin converting enzyme (ACE) inhibitors. Telmisartan has the longest biological half life (24 h) compared to any other antihypertensive drug and once in a day dose are the two basic principles for making its sustained release dosage form. [3] Hydrochlorothiazide is a diuretic drug used worldwide for lowering the blood...