Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone

Objective: Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel, and elucidate underlying physiochemical properties. Methods Drug release profiles from DPA50-MPC250-DPA50 gel (pH 7.5), over 32 hours (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS), and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM), and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM). Key Findings DPA50-MPC250-DPA50 copolymer (15 % w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data was consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles. Conclusions The DPA50-MPC250-DPA50 copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone. Keywords DPA-MPC-DPA, pH sensitive, Nanoparticles, Polymer gel, Drug delivery system, Controlled release