Is there a clinical interaction between low molecular weight heparin and non-steroidal analgesics after total hip replacement?

The benefits of parenteral non-steroidal analgesic drugs and low molecular weight heparin anticoagulants have been shown before, but there is concern that the use of these agents in combination may potentiate haemorrhagic side-effects because of simultaneous inhibition of the clotting cascade and platelet mechanisms of haemostasis. In a prospective controlled trial, 60 patients undergoing total hip replacement were randomised into two groups. Those in one group received intramuscular ketorolac and those in the other group opioid analgesia. All patients received enoxaparin subcutaneously, once daily. There were 34 patients in the NSAID group and 26 in the opiate group. There were no significant differences between the two groups for intraoperative blood loss, postoperative drainage, transfusion requirements, bruising, wound oozing and leg swelling. From this study it would appear that there is a low risk of significant haemostatic potentiation associated with concurrent use of low molecular weight heparin and a modest dose of ketorolac tromethamine.