Preparation and optimization of voriconazole microemulsion for ocular delivery

Optimized microemulsions (o/w type) of voriconazole were formulated for efficient ocular delivery. Optimized batches were selected through construction of phase diagrams following stability studies. No significant physiochemical interactions were found between the drug and excipient (oil and surfactant/co-surfactant) as confirmed by H NMR and FTIR studies. Drug content was found between 53 and 72% depending on size and composition. Selected microemulsion batches exhibited shear thinning properties with acceptable viscosities. Globule size analyzed by zetasizer as well as TEM images of selected batches were found within the desired range (<200 nm). In vitro release studies of microemulsions exhibited sustained release property (>70% in 12 h). Ex vivo permeation study also supported the enhanced drug flux through cornea from microemulsions. Based on size, surfactant/co-surfactant concentration, viscosity, drug content and release studies, the microemulsion batch ME-10 was selected for future in vivo studies.