ABSTRACT
<p><b>OBJECTIVE</b>To prepare sustained-release capsules of cinnamon oil with stearic acid, polyethylene glycol 6000 and gluceryl monostearate.</p><p><b>METHODS</b>After the solid dispersion of cinnamon oil was prepared by melting method, the effects of the process variables and formulation variables on solid dispersion and dissolution were investigated. The formulation and preparation process of cinnamon oil solid dispersion were optimized by orthogonal design, and Fourier-transformed infrared (FTIR) spectroscopy was employed to detect the possible molecular interaction between cinnamon oil and the adjuvants.</p><p><b>RESULTS</b>The in vitro release percentage of the optimized formula complied with the Higuchi equation, and the preparation allowed drug delivery for 12 h. Analysis with FTIR spectroscopy revealed interactions between cinnamon oil and the adjuvents and formation of the solid dispersion.</p><p><b>CONCLUSION</b>The solid dispersion capsules prepared through this simple and well reproducible process allow obviously sustained release of cinnamon oil.</p>