Determination of drug content in the implants

Determination of drug content in the MTX-loaded implants was performed according to the method stated in the Pharmacopoeia of the People’s Republic of China.16 Ten MTX-loaded implants were selected and weighed. Each implant sample was grounded in a pestle and mortar with a mixture of phosphate/citrate buffer (pH 6.0) and acetonitrile (90:10, v/v). The residue was further dissolved in an ultrasonic water bath for 20 min. The resulting suspension was centrifuged at 12,000 rpm for 10 min.17 Subsequently, an aliquot of the supernatant (20 µL) was analyzed by HPLC. The actual drug content of each implant was then calculated.