The objective of the present investigation is to improve the solubility of valsartan and prepare immediate release tablets.
To increase the solubility and bioavailability of valsartan, a low-soluble antihypertensive drug, immediate release dosage forms were formulated by a direct compression method using a solid dispersion technique with three different carriers (β-cyclodextrin, polyvinyl pyrrolidone K30 and poloxamer 188) at three different ratios (1:3, 1:4 and 1:5). Nine physical mixtures (PM1–PM9) were prepared and various physical parameters were characterised in
Out of the prepared physical mixtures, PM8 showed the best results, with 94.2% of the drug dissolving within 30 min. Formulation PM8 solid dispersion further used for the preparation of valsartan immediate release tablets by using sodium starch glycolate superdisintegrant, at different concentrations (3%, 4% and 5%; i.e., IF1, IF2 and IF3 formulations, respectively). The optimised formulation showed friability and disintegration values of 0.456±0.9 and 6.2±0.4 min. Among the three immediate release formulations, IF2, which contains 4% sodium starch glycolate, demonstrated an 84.46% drug release in 30 min and a 99.69% drug release in 1 hr, indicating increased drug solubility. When compared with a valsartan pure drug, the solubility of the solid dispersion increased by 135.06-fold.
The results show that the optimised IF2 formulation demonstrated enhanced drug solubility by 135.06-fold, using a solid dispersion technique with poloxamer 188. This can be explained by the conversion of crystalline to an amorphous form of drug, leading to a reduction in the contact angle between the drug and the gastric medium. It can be concluded that poloxamer 188 is a suitable carrier and that use of a physical mixture technique is an applicable method to improve the solubility of valsartan.