Formulation and evaluation of an enoxaparin aqueous spray for the treatment of contusions by topical application

Objectives Enoxaparin (ENX), an anticoagulant, was developed as a topical aqueous spray that provides rapid treatment for contusions by dissolving micro-clots, reducing inflammation, and thereby alleviating pain and edema.Significance This spray offers rapid relief of contusions, improves drug retention in the skin, and helps to restore the aesthetic appearance of injured skin.Methods ENX aqueous sprays were developed using an aqueous dispersion method with medium-chain triglycerides (MCTs) as permeation enhancers and propylene glycol (PG) used as a plasticizer. Two optimized formulations, FA9 (caproic acid-based) and FB8 (caprylic acid-based), were selected using a Box-Behnken design via surface response methodology. The various physicochemical and spray characteristics of optimized formulations were evaluated, and therapeutic efficacy was assessed in a contusion-induced animal model.Results The optimized formulations (FA9 and FB8) exhibited favorable drying time and transparency for topical applications. Drug deposition was significantly higher in FA9 (47.68% ± 4.61) and FB8 (38.25% ± 3.76) compared to the marketed formulation (31.52% ± 2.37). The in vivo animal study indicated that FA9 facilitated complete bruise resolution after five days in contusion-induced animals, whereas FB8 required one week to recover. Histological analysis confirmed rapid vascular and tissue recovery with FA9, while FB8 exhibited moderate healing due to deeper tissue injury, but optimized formulations healed faster than the marketed preparation.Conclusions The ENX aqueous spray containing MCTs demonstrated high therapeutic efficacy and faster bruise resolution than the marketed formulation, thus presenting a promising alternative for the topical treatment of contusions.