Optimal response surface design of Gum tragacanth-based poly[(acrylic acid)-co-acrylamide] IPN hydrogel for the controlled release of the antihypertensive drug losartan potassium

Abstract

The present study proposes the development and optimization of a new interpenetrating polymer network (IPN), consisting of Gum tragacanth, poly(acrylic acid) (PAA), and poly(acrylamide) (PAAm), for the in situ controlled release of losartan potassium under different pH conditions at 37 °C. Solvent amount and monomer concentration were chosen as the process variables and percentage swelling was taken as the process response. ANOVA model fits were made for the data and gave the cubic model as the best fit, with a predicted R² = 0.976. The maximum desirability was observed to be 19.63 mL solvent and 3.28 × 10⁻⁴ mol L⁻¹ monomer concentration, at which the percentage swelling was found to be 266. Whereas, at 23.7 mL solvent and 6.7 × 10⁻⁴ mol L⁻¹ monomer, the percentage swelling was found to be at the minimum (139%). The model was validated at the optimal points for developing devices with the maximum swelling capacity. Drug release through the synthesized matrix was found to show non-fickian behavior at pH 2.0, 7.0, and 9.2, with an increasing trend in gel characteristic constant (k). At each pH medium, the initial diffusion coefficient (D_I) was found to be higher than the lateral diffusion coefficient (D_L).