Preparation and evaluation of transnasal microemulsion of carbamazepine

The objective of this study was to develop novel transanasl microemulsion containing carbamazepine for treatment of epilepsy. Oleic acid was selected as oil while Tween 80 and propylene glycol were selected as surfactant and cosurfactant respectively based on solubility results. Optimized ratio of Tween 80: propylene glycol was selected after developing pseudoternary phase diagrams for different ratio and microemulsions were prepared. The prepared microemulsions were evaluated for globule size, viscosity, pH, conductivity and % transmittance. Ex-vivo diffusion study for optimized microemulsion was performed through sheep nasal mucosa wherein diffusion flux and permeability coefficients were determined. Further pharmacodynamic performance was evaluated in rats by electrically induced seizures. It was found that optimized microemulsion was stable and transparent with average globule size of 190 nm and diffusion flux of 75.77 μg cm−2 min−1 and showed no toxicity during histopathological evaluation on sheep nasal mucosa. Pharmacodynamic evaluation also indicated lesser intensity of seizures in rats treated with optimized formulation in comparison to rats treated with oral carbamazepine microemulsion and nasal carbamazepine solution which suggested carbamazepine transnasal delivery system as an effective alternate therapy for treatment of epilepsy.