process optimization and physicochemical evaluation of chlorzoxazone -loaded nanoemulsion gel for enhanced bioavailability

Chlorzoxazone (clz), a centrally acting skeletal muscle relaxant, exhibits inadequate water solubility and reduced bioavailability, limiting its therapeutic effectiveness. in this study, a self-nanoemulsifying drug delivery system (snedds) for clz was developed and further transformed into a nanoemulsion-based gel to improve topical delivery. the optimized snedds, prepared using sesame oil, tween 80, and peg 400, exhibited a particle size of 24 ± 0.5 nm, zeta potential of –26.4 mv, and drug release of 98.03% within 60 min, showing excellent agreement with the predicted values. the nanoemulgel was formulated using carbopol 934 and triethanolamine as gelling agents, achieving a drug content of 92.63 ± 1.2%. in vitro dissolution studies demonstrated superior drug release compared to that of pure clz, with a cumulative release of 92.04% for the optimized formulations. viscosity (3123 ± 15 cps), spreadability (15.4 g·cm/s), and ph (5.8 ± 0.02) confirmed the suitability for skin application. skin permeation studies revealed controlled penetration with significantly higher release profiles than those of conventional formulations. in vivo skin irritation studies in new zealand white rabbits confirmed that the formulation was a non-irritant, while histopathological analysis showed normal dermal and epidermal architecture, ensuring biocompatibility. stability studies conducted over 90 days demonstrated that refrigerated samples preserved the drug content (89.16%) and physical properties, whereas room-temperature storage led to phase separation and reduced stability. the clz-loaded nanoemulgel successfully combined the solubilization advantages of snedds with the localized delivery benefits of gels, providing a promising strategy for enhanced therapeutic efficacy in the management of muscle spasms.