Abstract

FACTORIAL STUDIES ON ENHANCEMENT OF DISSOLUTION RATE AND FORMULATION OF VALSARTAN TABLETS EMPLOYING ?CD AND KOLLIPHOR HS15

T. Srinivasa Rao, and K.P.R. Chowdary *

ABSTRACT

Valsartan is an anti hypertensive drug. It belongs to class II under Biopharmaceutical classification system and exhibit low and variable oral bioavailability due to its poor solubility. It is practically insoluble in water and aqueous fluids and its oral absorption is dissolution rate limited. It needs enhancement in solubility and dissolution rate for improvement of its oral bioavailability and therapeutic efficacy.The objective of the present study is enhancement of dissolution rate and formulation development of valsartan tablets with fast dissolution characteristics employing βCD and Kolliphor HS15, a non ionic surfactant.The individual and combined effects of βCD (factor A) and Kolliphor HS15 (factor B) on the dissolution rate of valsartan from solid inclusion complexes and their tablets were evaluated in a series of 22 factorial experiments. The feasibility of formulating valsartan - βCD-Kolliphor HS15 inclusion complexes into tablets with fast dissolution rate characteristics was also investigated. Kolliphor HS15 has not been investigated earlier for this purpose. The individual and combined effects of βCD and Kolliphor HS15 in enhancing the dissolution rate and dissolution efficiency of valsartan from solid inclusion complexes and their tablets were highly significant (P < 0.01). The dissolution of valsartan was rapid and higher in the case of valsartan- βCD and valsartan- βCD - Kolliphor HS15 complexes prepared when compared to valsartan pure drug. β CD alone gave a 5.76 fold increase and in combination with Kolliphor HS15 it gave 9.58 fold increase in the dissolution rate of (K1) of valsartan. Valsartan –βCD – Kolliphor HS15 inclusion complexes could be formulated into compressed tablets by wet granulation method and the resulting tablets also gave rapid and higher dissolution of valsartan. Valsartan tablets formulated with βCD and Kolliphor HS15 individually gave 9.8 and 12.6 fold increase in the dissolution rate and thosecontaining drug - βCD -Kolliphor HS15 complex gave much higher enhancement (45.2 fold) in the dissolution rate when compared to tablets formulated with valsartan pure drug. Combination of βCD and Kolliphor HS15 gave much higher enhancement in the dissolution rate of valsartan tablets than is possible with them individually. A combination of βCD with Kolliphor HS15 is recommended to enhance the dissolution rate in the formulation development of valsartan tablets with fast dissolution rate characteristics.

Keywords: Valsartan, ? Cyclodextrin, Kolliphor HS15, Dissolution Rate, Valsartan Tablets, Formulation development.