Prevention of postoperative deep vein thrombosis by two different heparin types

The effectiveness of two different heparin types in preventing deep vein thrombosis after surgery was studied in 173 patients, randomly assigned to treatment by a new low molecular weight (LMWH) heparin or trade calcium heparin (CH). Both drugs were administered subcutaneously, 2 h before surgery and for 7 days after, at dose of 7,500 anti activated factor X Units once a day in low molecular weight heparin group, or 5,000 International Units t.i.d. in calcium heparin group. Both activated factor X inhibition and activated partial thromboplastin time evaluations were performed before the surgery, and 3 and 7 days after, to monitor drug effects. Results clearly demonstrated that low molecular weight heparin exerts a marked inhibition on plasma activated factor X. On the contrary, calcium heparin was less powerful in inhibiting this coagulation factor. Both drugs revealed a lower effectiveness in increasing activated partial thromboplastin time. Efficacy in preventing postoperative thrombo-embolism appeared about 3 times higher for the new low molecular weight heparin, despite the lower daily administration numbers. No major side effects related to drug were observed in both treatment groups; also hemorrhage frequency was the same. No differences related to the operation type were found in preventive actions of both drugs.(ABSTRACT TRUNCATED AT 250 WORDS)