Improved in vitro Release and ex vivo Permeation of Zotepine as Microemulsion Gel Formulation through Transdermal Application
Zotepine is atypical antipsychotic drug with poor oral bioavailability due to first-pass metabolism and poor aqueous solubility. The objective of the current investigation was preparation and ex vivo characterization of Zotepine (ZT) loaded microemulsion (ZT-ME) and microemulsion gel (ZT-MEG) for enhanced transdermal delivery. ZT-ME formulation was prepared with 7.5% oleic acid, 30% w/v of Tween80 and 30%w/v of absolute ethanol as oil, surfactant and cosurfactant, respectively. Optimized ZT-ME formulation was selected and converted to ZT-MEG using carbopol as gelling agent. ZT-ME and ZT-MEG subjected to in vitro release and ex vivo permeation studies through rat skin, comparison with ZT coarse suspension (ZT-CS). ZT-ME formulation showed desirable physicochemical properties and stable with dilution stress. Prepared ZT-MEG formulation has showed better rheological behaviour and good spreadability. ZT-ME and ZT-MEG showed prolonged release compared with ZT-CS formulation over 24 h. ZT-ME and ZT-MEG exhibited 5-folds and 3.5-folds in permeation through rat skin compared with ZT-CS formulation. Overall, ZT-MEG formulation could be considered as an alternative delivery approach for enhanced skin delivery.