Essential Oil based Microemulsions for Intranasal Delivery of Venlafaxine HCl

An aim of the study was to develop microemulsion based intranasal delivery of venlafaxine HCl for effective treatment of depression by targeting brain. Saturation solubility studies were carried out to determine the solubility of drug in various oils, surfactants and co-surfactants. Microemulsions were prepared using eucalyptus oil as oil phase, tween 80 and ethanol as surfactant and co-surfactant respectively. Pseudo-ternary phase diagrams were plotted to determine the formation of microemulsion using water titration method. Drug loaded microemulsions were further characterized for in vitro and ex vivo drug diffusion studies, zeta potential, polydispersibility index, pH, viscosity and stability studies at various temperatures. Differential Scanning Calorimetry and Fourier Transform Infra Red Spectroscopy were done to verify any drug excipient incompatibility. Microemulsion with Smix: oil ratio 1:1 (F1) was found to be stable having pH of 6.2±0.2 with viscosity of 90.0±2 cps. In vitro and ex vivo studies results showed 98.33±0.39 and 81.58±1.56 percent of drug diffusion respectively for a period of 6h as compared to other formulations. The microemulsion (F1) showed a good average globule size of 218.9 nm, polydispersity index of 0.372 and zeta potential of -23.4 mV. Studies showed absence of interaction between drug and excipients. The above results indicated good difffusion properties of developed microemulsions for a period of 6h. A polydispersity index and zeta potential value indicates uniform distribution of globules and good stability of microemulsions. Microemulsion based intranasal delivery of Venlafaxine HCl could be a potential delivery to treat depression.