Formulation and Development of W/O Type Microemulsion based Transdermal Systems for Verapamil Hydrochloride

Abstract

The aim of the present investigation was to design and develop a novel microemulsion (ME) based transdermal drug delivery system of highly water soluble drug, verapamil HCl (VPLH) to enhance its therapeutic efficacy. Microemulsion based transdermal formulation was used to circumvent barrier properties of stratum corneum due to its lower droplet size as well as permeation enhancing effects. VPLH loaded water droplet are dispersed in oils (W/O) MEs were optimized using Box - Behnken design with amounts of oil (Capmul MCM), surfactants mixtute (Span 80 and ethanol) and water as independent variables. The critical responses; globule size, viscosity, cumulative amount of drug permeated across abdominal skin of goat in 24 h (Q24) and lag time (tL) were identified and probed as dependent variables. The optimized batch of VPLH loaded ME was further converted into microemulsion based gel (MBG) in order to increase patient compliance. The results of in-vitro permeation of the optimized batch of VPLH loaded MBG revealed significant increase in permeability parameters as compared to its convention gel formulation. The values of flux (Jss) for optimized batch of VPLH loaded MBGs (0.5214 mg/cm2h) revealed 12.08 cm2 area requirement in order to obtain the desired input rate of VPLH within 24 h application. All these results suggested suitability of W/O type MEs as carriers for transdermal delivery of highly water soluble drug, VPLH.