Microemulsion-based patch for transdermal delivery of huperzine A and ligustrazine phosphate in treatment of Alzheimer's disease.

The aim of the present study was to construct an innovative microemulsion-based patch for simultaneously transdermal delivery of huperzine A (HA) and ligustrazine phosphate (LP). The pseudo-ternary phase diagrams for microemulsion region were developed using oleic acid as oil, Cremophor RH40 as a surfactant, and ethanol as a cosurfactant. 1,8-cineole was added to the microemulsion as a penetration enhancer. The microemulsion-based transdermal patches were prepared by the lamination technique. The permeation studies were performed in vitro to evaluate the abilities of various microemulsions and transdermal patches to deliver HA and LP across the rat abdominal skin, showing that microemulsions increased the permeation rates of HA and LP compared with the control, and the penetration kinetics of the transdermal patch was in a zero order process. The results of the pharmacodynamic studies indicated that the transdermal combination therapy of HA and LP showed more benefits for fighting against amnesia in comparison with monotherapy. The anti-amnesic effects were also confirmed in scopolamine-induced amnesia rats after transdermal administration at multiple doses for 9 consecutive days, and the efficacy exhibited a dose-dependent manner. As a conclusion, the microemulsion-based transdermal patch containing HA and LP might provide a feasible strategy for the prevention of Alzheimer's disease.