Preparation and in vitro Evaluation of Silodosin Solid Dispersions by Solvent Evaporation Method

Introduction: Solid dispersions are considered one of the promising techniques for increasing the dissolution rate of drugs, as more than 40% of new drugs are poorly soluble in water, and the drug substance, in order for it to be absorbed, must be in the form of a solution at the site of absorption. The poor aqueous solubility of Silodosin led to a decrease in its dissolution rate, and thus a decrease in its bioavailability after oral administration. Therefore, solid dispersions of Silodosin were prepared in order to improve its dissolution rate.

Materials and Methods: Solid dispersions were prepared by solvent evaporation method using polyvinylpyrrolidone k30 in different weight ratios (1:3 and 1:6 Silodosin: polyvinylpyrrolidone k30), and a combination of polyvinylpyrrolidone k30 with poloxamer 407 in different weight ratios (1:6:1 and 1:6:3 Silodosin: polyvinylpyrrolidone k30: poloxamer 407).

Results: Based on studies of drug dissolution rates from solid dispersions, S3 (1:6:1) (Silodosin: polyvinylpyrrolidone k30: poloxamer 407) gave the highest dissolution rate according to a Two-Tailed Student's T-Test (P < 0.05). (FTIR) and (DSC) indicated that there were no interactions between Silodosin and the used excipients.

Conclusions: The dissolution rate of Silodosin when formulated as solid dispersions was improved compared to the pure drug, and the percentage of drug released in solid dispersion S3 after one hour was approximately 98.5%.