FACTORIAL STUDIES ON ENHANCEMENT OF DISSOLUTION RATE OF TELMISARTAN TABLETS BY CD COMPLEXATION AND SOLID DISPERSION TECHNIQUES

Telmisartan, 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. Because of poor aqueous solubility and dissolution rate it poses challenging problems in its tablet formulation development. It needs enhancement in the dissolution rate in its formulation development. The objective of the present study is to enhance the dissolution rate of telmisartan tablets by two techniques namely i) Complexation by β CD alone and in combination with Tween 80 and ii) Solid dispersion in Primojel alone and in combination with Tween 80. The individual and combined effects of β CD, Primojel and Tween 80 in each case were evaluated in 2 2 factorial experiments. A comparative evaluation of the two techniques was also made. Telmisartan (40 mg) tablets were formulated in each case i.e.CD complexation and Solid dispersion techniques as per 22 factorial design. The two factors in CD complexation are β CD and Tween 80 and the two factors in solid dispersion technique are Primojel and Tween 80. The two levels of Factor A (β CD or Primojel) are 0 and 1:3 ratio of drug: carrier and the two levels of the Factor B (Tween 80) are 0 and 4% of drug and carrier content. Four telmisrtan tablets (40 mg) were formulated in each technique using selected combinations of the levels of the two factors. The tablets were prepared by direct compression method and the prepared tablets were evaluated for hardness, friability, disintegration time, drug content and dissolution rate and efficiency. The dissolution rate and dissolution efficiency of telmisartan tablets were markedly enhanced by CD complexation and Solid dispersion techniques. In both the techniques the individual and combined effects of the factors involved i.e. β CD and Tween 80 in CD complexation and Primojel and Tween 80 in the case of solid dispersion technique, are highly significant (P < 0.01). Solid dispersion technique gave higher enhancement in the dissolution rate of telmisartan tablets than CD complexation technique. In both the techniques combined carriers gave higher enhancement in the dissolution rate than the carriers individually. Formulations CDab and SDab gave respectively 7.14 and 9.10 fold increase in the dissolution rate of telmisartan tablets. The dissolution efficiency of the telmisartan tablets was also significantly enhanced by CD complexation and Solid dispersion techniques. Key words: Telmisartan tablets, Dissolution rate, Cyclodextrin complexation, Solid dispersion technique, β CD, Primojel, Tween 80, Factorial stud