Investigation on release of MTX combined with calcium sulfate in vitro

B39

Abstract
 The purpose of the study was to investigate the character of drug release of calcium sulfate (OSTEOSET®) combined with MTX in the circumstance of Tris-buffered natural saline. The drug particles combined with 20 mg MTX, 4% in weight percentage, were made manually. The experiment was carried under the condition of 37°C in temperature, rotation rate 50rpn. The mimesis of body fluid was Tris-buffered natural saline. The extraction method was adopted. Samples were collected every 2 hours in the first 24hours and everyday in the next 20 days. The drug concentration of each sample was analyzed through high performance liquid chromatogram. Twenty-five particles were put into the experiment, and twenty were observed throughout the experiment. The average drug concentration of the first two hours was 10.535mg/L, the highest of the first twenty-four hours, and maintains between 4 mg/L and 6mg/L latterly. There was an exponential relation between the accumulative drug concentration and the square root of sampling time. As a carrier, OSTEOSET® combined with 4% MTX, totally drug amount to 20 mg per drug particle, the drug release was faster in the first 3 days, remained in a steady state for 15 days. The drug concentration maintains 65mg/L and 100mg/L in the steady period. It was a quite ideal local drug release carrier.
 Key Words: Calcium sulfate, Drug implants, MTX, HPLC