Formulation Optimization and Characterisation of Doxycycline Hyclate-Loaded Nanoemulgel for the Management of Topical Bacterial Infection

Abstract Bacterial infection poses a significant challenge in many critical chronic skin infections, such as diabetic wounds and multidrug-resistant infections. The present study aims to optimise doxycycline hyclate-loaded herbal oil-based nanoemulsion. Various formulations were prepared according to the Box Behnken Design, and particle size, polydispersity index (PDI) and zetapotential were analysed. A stable optimised formulation was loaded in Carbopol 974 (0.5-1.5%) nanoemulgel and evaluated for appearance, viscosity, drug content, and drug release. The best formulation was evaluated for ex-vivo permeation efficiency and skin penetration by Confocal Laser Scanning Microscopy. The optimised nanoemulsion was found to have a particle size of 24.04 nm, Zeta potential – 10.86mV, and PDI 0.1847. In-vitro drug release studies showed a sustained release pattern over 24 h and followed the Higuchi model (R2 = 0.80) release kinetics. Ex vivo skin permeation studies revealed that DH-NEG permeates through the membrane at 2.7954 µg/cm²/hr, and the conventional gel permeates 1.56 µg/cm²/hr. The study concluded that the optimised DH-loaded nanoemulgel formulation has promising application due to its enhanced permeation ability, improved physicochemical stability and above all, it has a sustained drug release profile. The therapeutic efficacy of DH will be improved by the presence of cinnamon oil.