Multiple hour antifibrotic drug release enabled by a thermosensitive quadpolymer

Injectable drug delivery for uterine fibroid therapy is an ambitious, possibly fertility-preserving concept, that could meet the challenges associated with the structure of these tumors and their location in the uterus. This study was conducted to advance a thermosensitive injectable quadpolymer for effective sustained release of anti-fibrotic drug formulations and to evaluate the feasibility of its use for delivery of the anti-fibrotic drug pirfenidone as a therapy to reduce fibroid cell proliferation. A series of quadpolymers were prepared by free radical polymerization of N-isopropylacrylamide (NIPAM) with different amounts of polylactic acid functionalized hydroxyethyl methacrylate (HEMA-PLA), acrylic acid (AAc), and methacrylate functionalized hyperbranched polyglycerol (HPG-MA) to optimize the sol-gel phase transition temperature and mechanical stiffness. Poly(NIPAM-co-HEMA-PLA-co-AAc-co-HPG-MA) with feed ratio (83-7-1-9), at 17% w/v, readily formed an aqueous solution that could be manipulated by syringe at room temperature. The quadpolymer also rapidly formed a stable gel at physiological body temperature, and partially biodegraded over time as confirmed by several spectroscopic characterization techniques. To evaluate the potential range of utility, quadpolymer 83-7-1-9 was loaded in-vitro with caffeine (a prototype hydrophilic drug) or the hydrophobic drug pirfenidone. Pirfenidone-loaded quadpolymer 83-7-1-9 formulations released 50% of drug loaded in double the time as compared to other reported liposome and nanoparticle injectable pirfenidone formulations. Furthermore, treatment of cultured fibroid cells with pirfenidone-loaded quadpolymer 83-7-1-9 formulations confirmed that activity of pirfenidone was preserved and proliferation of fibroid cells was inhibited. These results support that quadpolymer 83-7-1-9 is a promising candidate to be further developed for localized delivery of drugs for uterine fibroid therapy.