Controlled release of testosterone propionate based on poly N-vinyl pyrrolidone/2-acrylamido-2-methyl-1-propanesulfonic acid hydrogels prepared by ionizing radiation

Abstract

Stimuli-responsive hydrogels, based on 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) and poly N-vinyl 2-pyrrolidone (PVP) were synthesized via γ-ray irradiation technique to use as drug delivery system. The structure of PVP/AMPS hydrogels was confirmed using FT-IR, its morphology was studied using scanning electron microscopy (SEM) and the thermal properties were simultaneously studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Swelling behavior of the hydrogels was studied as a function of PVP:AMPS composition and irradiation dose in addition to temperature, pH and [NaCl] of the swelling medium. This work discusses the swelling kinetics of hydrogels and release dynamics of testosterone propionate (TP) as a model drug; from the hydrogel for the evaluation of swelling and drug release mechanisms. It has been observed from the release dynamics of drug that diffusion exponent ‘n’ have 0.61, 0.77 and 0.63 values and gel characteristics constant ‘k’ have 13.5 × 10⁻³, 7.0 × 10⁻³ and 19.5 × 10⁻³ values for the TP release, respectively, in distilled water, pH 2 buffer and pH 7 buffer. The ‘n’ values indicate that the swelling and release of drug from the hydrogels followed non-Fickian diffusion mechanism. In this mechanism, the rate of drug diffusion from the polymer matrix and rate of polymer chain relaxation are comparable. It has also been observed from the swelling and release of drug in the different pH buffer that the polymer matrix is pH responsive and can be exploited for the delivery of testosterone propionate drug to the colon.