Effect of Excipients and Processing Parameters on Floating Characteristics of Hydrodynamically Balanced System for Diltiazem Hydrochloride

The hydrodynamically balanced system (HBS) is based on the gel forming hydrocolloids which swells when comes in contact with water resulting in dosage form with density less than unity10,11. The orientation of charged hydrophilic groups towards water results in HBS phenomenon. Hydrocolloids used are hydroxypropylmethyl cellulose derivatives. The present study deals with formulation of diltiazem HCl HBS. The effect of polymer viscosity, processing parameter on floating characteristics and drug release was studied. A direct compression method and 1:1 to 1:5 ratio of drug: HPMC K4M, K15M and K100M were used for development of HBS. The floating characteristic and in vitro drug release was studied in pH 1.2 buffer. The effect of hardness on floating behavior of HBS was studied. An increase in hardness resulted in non-floating dosage form. The HBS tablets containing 1:1 ratio of drug: polymer were found to be non-floating even at low hardness values. Hence, by varying the hardness, the floating characters can be obtained. Invitro drug release profile reveals that increase in drug: HPMC ratio resulted in retardation of drug release.