Thermosensitive hydrogel-based drug delivery system for sustained drug release

Hydrogels are unique biomaterials that have demonstrated tremendous potential in sustaining drug release. Significant effort has been made to impart stimuli sensitivity and incorporate hydrophilic molecules in a stable hydrogel network. Although, thermosensitive hydrogels have exhibited promising interventions, formulation of a biodegradable, stable thermosensitive hydrogel for sustained drug release remain to be vastly studied. Here, a novel micellarization strategy was exploited to achieve a biodegradable thermosensitive hydrogel with improved stability. Two triblock co-polymers, PCL-PEG-PCL (600-2000-600) and PCL-PEG-PCL (1000-2000-1000) with different physical properties were employed to achieve optimal critical gelling concentration and critical solution temperature (LCST) that can form a stable hydrogel network at body temperature. A library of triblock co-polymers were synthesized utilizing epsilon-caprolactone and poly ethylene glycol (PEG) of various chain lengths. The block co-polymers exhibiting desired physical properties were further characterized using NMR and GPC analytical techniques. Release study of diclofenac sodium was examined in presence of the thermosensitive hydrogel. The results indicated that the hydrogel sustained the release of diclofenac sodium by 100-folds. Kinetic models further suggested a first order release rate, indicating that the release is primarily mediated by diffusion through porous membranes of the hydrogel. Such hydrogel based drug delivery system promises an effective strategy for sustaining drug release for the treatment of diseases.