Effect of Formulation Parameters on Skin Flux of Demopressin Microemulsion

Transdermal drug delivery systems are considered in recent years as a promising alternative to oral delivery and hypodermic injections.The present work reports on the development of water-in-oil (w/o) emulsions for the transdermal administration of desmopressin acetate. Microemulsion components included: Tween80 and Span80 (surfactants), 1-decanol (co-surfactant), and isopropyl myristate (oil phase). The effects of formulation components, hydrophilic-lipophilic balance (HLB,7-9), ratio of surfactants and co-surfactant mixture to oil phase (Smix/oil,5:5-7:3) and ratio of surfactants to co-surfactant (S/Cs, 2:1- 5:1) on skin flux was evaluated using Design-Expert software 7.0.0. It was concluded that skin flux was increased when S/Cs and Smix/oil were decreased and by increasing HLB skin flux enhanced. The following optimized formulation was obtained by the software: HLB = 8, S/Cs = 3, and Smix/oil = 5.46. Stability and skin permeation of optimized formulation was measured. Based on the results of this research, by reducing the viscosity and increasing the system polarity, drug skin flux of microemulsion increases. Studies of skin permeation show that transdermal drug delivery of large-molecule drugs because of small dimensions and ingredients that act as skin enhancers are possible.