Investigation of microemulsion system for transdermal delivery of meloxicam.

A new oil-in-water microemulsion containing 0.375% meloxicam was developed in order to improve the skin permeability of meloxicam. Among various surfactants and cosurfactants investigated in the microemulsion system, polyoxyethylene sorbitan trioleate (Tween 85) showed excellent solubility and ethanol expressed skin permeation enhancing effect for meloxicam. The microemulsion existence ranges were defined through the construction of the pseudo-ternary phase diagram. The effect of the content of isopropyl myristate (IPM) and the effect of the mass ratio of the surfactant/cosurfactant (Km) on skin permeation of meloxicam were evaluated with excised rat skins. The optimum formulation with the highest skin permeation rate (5.40 microg/cm2/h) consisted of 0.375% meloxicam, 5% IPM, 50% Tween 85/ethanol (1:1) and water.