Design and Validation of a Stability-Indicating RP-HPLC Method for Quantifying Silodosin and Dutasteride in Both Bulk and Dosage Forms, as Well as in Human Plasma.

Abstract

A cost-effective, stability-indicating RP-HPLC method was successfully developed and validated for the simultaneous determination of Silodosin and Dutasteride in both bulk and pharmaceutical formulations. The RP-HPLC analysis utilized a C18 Column (4.6 x 250 mm, 5μm particle size), with a mobile phase consisting of mixed buffer and methanol in a 0.1% OPA in water ratio (70:30). The column temperature was maintained at 25oC, with a flow rate of 0.7 ml/min and an injection volume of 20μl. Detection was performed at 231nm. Validation of the method demonstrated linearity for Silodosin and Dutasteride in the concentration ranges of 20-100 μg/ml and 1.5-6.25 μg/ml, respectively, with regression values of 0.9997 for Silodosin and 0.999 for Dutasteride. Susceptibility studies revealed that Silodosin and Dutasteride were highly vulnerable to peroxide (19.12 & 19.50) and basic conditions (18.01 & 17.45), while exhibiting lower susceptibility to acidic (13.86 & 15.44) and hydrolytic conditions (1.11 & 0.47). Precision studies demonstrated % RSD values less than 2% for both drugs across all selected concentrations. The limit of detection (LOD) and limit of quantification (LOQ) were determined as 0.505 μg/ml and 1.53 μg/ml for Silodosin, and 0.079 μg/ml and 0.241μg/ml for Dutasteride, respectively. The method adhered to International Conference on Harmonization (ICH) guidelines during validation.