Effect of particle morphology and pore size on the release kinetics of ephedrine from mesoporous MCM-41 materials

Ephedrine was loaded onto siliceous mesoporous materials of different pore sizes, and the corresponding drug release into simulated body fluid at pH 7.4 and 37 A degrees C was measured against time over a period of 72 h. The mesoporous materials designated MCM-41(C-N) were prepared at different pore sizes using a self-assembly mechanism. The pore size was controlled by the use of alkyltrimethylammonium bromide (C(N)TAB) surfactants having different alkyl chain lengths (C-10, C-12, and C-14). The three mesoporous materials showed good ephedrine-loading capacities from dry ethanolic solutions, which slightly increased with the pore size of MCM-41(C-N). From the drug release profiles, the overall release of ephedrine followed the order: MCM-41(C-12) > MCM-41(C-14) > MCM-41(C-10), with the release of ephedrine attaining 92% of the drug load from MCM-41(C-12). Ephedrine release approached 60% of the drug load in 6 h and 92% in 20 h. The results of in vitro release kinetics indicate that pore size is not the only factor affecting ephedrine release, but also pore channel length and overall particle morphology.