Abstract

OPTIMIZATION OF IRBESARTAN TABLET FORMULATION BY 22 FACTORIAL DESIGN

Ch. Tarakaramarao and K. P. R. Chowdary*

ABSTRACT

Irbesartan, a widely prescribed anti hypertensive drug belongs to class II under BCS classification and exhibit low and variable oral bioavailability due to its poor aqueous solubility. It needs enhancement in the dissolution rate in its formulation development. Complexation with β-cyclodextrin (βCD) and use of Crospovidone are tried for enhancing the dissolution rate of irbesartan in its formulation development. The objective of the present study is optimization of irbesartan tablet formulation employing βCD and Crospovidone by 22 factorial design. Formulation of irbesartan tablets with NLT 85% dissolution in 10 min employing βCD and Crospovidone was optimized by 22 factorial design. Four irbesartan tablet formulations were prepared using selected combinations of the two factors as per 22 factorial design. Irbesartan tablets were prepared by direct compression method and were evaluated for drug content, hardness, friability, disintegration time and dissolution rate characteristics. The dissolution rate (K1) values were analysed as per ANOVA of 22 factorial design to find the significance of the individual and combined effects of the two factors (βCD and Crospovidone) involved on the dissolution rate of irbesartan tablets formulated. The individual and combined effects of βCD (Factor A) and Crospovidone (Factor B) on the dissolution rate (K1) of irbesartan tablets are highly significant (P < 0.01). Irbesartan tablets (Fb) which are prepared employing βCD in 1:1 ratio of drug: βCD and Crospovidone at 30% of drug content disintegrated rapidly within 20 seconds and gave 92.20% dissolution in 10min. Higher levels of βCD and lower levels of Crospovidone gave low dissolution rates of Irbesartan tablets. The increasing order of dissolution rate (K1) observed with various formulations was F b > Fab > F1 > Fa. The polynomial equation describing the relationship between the response i.e. percent drug dissolved in 10min (Y) and the levels of βCD (X1) and Crospovidone (X2) based on the observed results is Y = 55.833 – 5.557(X1) +31.492(X2) +0.682(X1 X2). Based on the above polynomial equation, Irbesartan tablet formulation with NLT 85% dissolution in 10 min could be formulated employing βCD at 1:3 ratio of drug: βCD (300 mg per tablet) and Crospovidone at 28.96 % of drug content (28.96 mg per tablet). The optimized Irbesartan tablet formulation, Fopt gave 85.45% dissolution in 10min fulfilling the target dissolution set. The results indicated validity of the optimization technique employed and the polynomial equation developed could be used to formulate irbesartan tablets with the desired dissolution rate specification. Hence formulation of irbesartan tablets with the desired dissolution rate specification (85% dissolution in 10 min) could be optimized by 22 factorial design.

Keywords: Irbesartan tablets, Optimization, ?-cyclodextrin, Crospovidone, Factorial Design.