Discriminatory dissolution testing for liquisolid compacts containing a poorly water-soluble drug (Hydrochlorothiazide)

Drug release from liquisolid compacts is dependent on several variables and changes in experimental parameters, like drug loading and the type and quantity of the carrier material, which affect the dissolution rate, significantly. Therefore, a dissolution method is needed that can discriminate among in vitro release profiles of liquisolid compacts of varying nature. The objective of this study was to develop and validate a discriminatory dissolution testing method for liquisolid compacts of hydrochlorothiazide (HCTZ) to evaluate the effect of formulation and process variables on dissolution rate. Various experimental conditions were optimized, and the method was validated according to USP and ICH guidelines for different parameters like linearity, specificity, accuracy, precision, and stability of solution. Analysis of dissolution samples was carried out by high-performance liquid chromatography (HPLC). The discriminatory nature of the method was confirmed by determining dissolution rates of liquisolid compacts of HCTZ prepared with different load factors. A model-independent approach was applied for comparison of different dissolution profiles. Based on a screening study, USP apparatus I (basket method) was selected. The best in vitro dissolution profile was obtained using purified water containing Tween-80 (0.5% v/v) as the dissolution medium (900 mL), stirred at 75 rpm. Complete dissolution (99.83 ± 1.03%) was achieved within 60 min and dissolution media had no interference with sample analysis. HCTZ exhibited a linear response (r2 = 0.9974) in the selected dissolution medium and showed accurate results (98%–100%) in the concentration rage of 80%–120% of the dose. All validation parameters were found in acceptable range (%RSD > 2), and drug samples prepared in dissolution medium were stable for the specified period. Comparison of dissolution profiles in the official and developed media showed significant differences in f1 and f2 values. The developed dissolution test exhibited higher discriminative capacity in differentiating release profiles of HCTZ and can be applied during formulation development and quality control analysis of liquisolid compacts