Stability of enoxaparin sodium in polymethyl methacrylate bone cement

Abstract

Objective To investigate the polymerization process of polymethyl methacrylate (PMMA) bone cement, and the effects of exothermy on the stability of enoxaparin sodium (ES) added. Methods 8 000 AXaIU enoxaparin sodium was added to 40 g Palacos® R PMMA bone cement and the enoxparin sodium cement cylindrical test specimen was prepared according to ISO5833: 2002 Surgical Implants-Acrylic Resin Bone Cement standard. It was leached with pH 7.4 Tris-HCL buffer for 24 h. The antithrombotic activity and anticoagulant activity of the extract were determined and compared with the standard enoxaparin sodium dissolution. Results The release system of 8000 AXaIU enoxaparin sodium added to 40 g Palacos® R PMMA bone cement had an anti-Ⅹa factor activity of 0.847 AXaIU/ml for 24 h, which had obvious antithrombotic activity, could significantly prolong rabbit plasma recalcification time and exert good anticoagulant activity. After the ES pure powder or ES-PMMA bone cement was treated at 75 ℃ for 10 min, there was no significant change in anti-Ⅹa factor activity or anticoagulant activity. Conclusion ES can withstand PMMA bone cement polymerization and exothermic process, maintain its own anti-thrombation and anticoagulant effect, and has the potential to be compounded into PMMA bone cement. Key words: Sodium enoxaparin; Polymethyl methacrylate; Bone cement; Polymerization; Thermal stability