The effect of meloxicam/ethanolamine salt formation on percutaneous absorption of meloxicam

Abstract

This study was undertaken to prepare meloxicam-ethanolamine salts (MX-EAs) that enhance the transdermal delivery of meloxicam. The physicochemical properties of MX-EAs were investigated by solubility measurements, Differential Scanning Calorimetry (DSC), and Infrared Spectroscopy (FT-IR). The DSC thermogram and FTIR spectra indicated that meloxicam formed salts with ethanolamines. The effects of various vehicles on the percutaneous absorption of meloxicam and of its salts across hairless mouse skin were evaluated using a flow-through diffusion cell system at 37 degrees C. Salt formation lowered the melting point of meloxicam and slightly reduced its octanol/water partition coefficient. Meloxicam-monoethanolamine salt (MX-MEA) and meloxicam-diethanolamine salt (MX-DEA) had greater solubilities and transdermal permeation rates across hairless mouse skin than meloxicam alone in various vehicles. Moreover, although the solubility of meloxicam-triethanolamine salt (MX-TEA) was generally lower than that of meloxicam, its permeation rate across the skin was higher. The fluxes of meloxicam and its salts were generally lower than those of piroxicam.