ENHANCEMENT OF DISSOLUTION RATE OF TELMISARTAN BY SOLID DISPERSION IN STARCH 1500 AND SOLUPLUS ALONE AND IN COMBINATION

Telmisartan, a widely prescribed antihypertensive drug belongs to class II under BCS and exhibit low and variable oral bioavailability due to its poor aqueous solubility. As such it needs enhancement in the dissolution rate and bioavailability to derive its maximum therapeutic efficacy. The objective of the present study is to prepare and evaluate solid dispersions of Telmisartan in Starch 1500 and Soluplus alone and in combination for enhancing the dissolution rate and dissolution efficiency of Telmisartan. The individual and combined effects of the two carriers, Starch 1500 and Soluplus in enhancing the dissolution rate and dissolution efficiency of Telmisartan were evaluated in a 22 factorial study. Solid dispersions of Telmisartan in Starch 1500 alone were prepared using four ratios of drug: carrier namely 2:1, 1:1, 1:2 and 1:3 by solvent evaporation method. Solid dispersions of Telmisartan in Soluplus alone were prepared at three concentrations namely 0.5, 1.0 and 2% by common solvent method. Solid dispersions of Telmisartan in combined carriers namely Starch 1500 and Soluplus were prepared as per 22 factorial design. All the solid dispersions prepared were evaluated for drug content uniformity, dissolution rate and dissolution efficiency in comparison to Telmisartan pure drug. The dissolution rate and dissolution efficiency of Telmisartan could be significantly enhanced by solid dispersion in Starch 1500 and Soluplus alone and in combination. The individual and combined effects of Starch 1500 and Soluplus in enhancing the dissolution rate and dissolution efficiency of Telmisartan are highly significant (P < 0.01). Soluplus gave significant enhancement in the dissolution rate of Telmisartan at very low concentrations where as a large proportion of Starch 1500 is required for a similar enhancement in the dissolution rate of Telmisartan. Combination of Starch 1500 and Soluplus resulted in a much higher enhancement in the dissolution rate and dissolution efficiency of Telmisartan than is possible with them individually. Combination of Starch 1500 and Soluplus is recommended for enhancing the dissolution rate and dissolution efficiency of Telmisartan. Key words: Telmisartan, Solid dispersion, Dissolution Rate, Starch 1500, Soluplus, Factorial stud