Pharmacodynamic effects on blood coagulation of a new low molecular weight heparin (alfa-LMWH) in healthy volunteers and gynecological surgery patients.

The pharmacodynamic properties of a new LMWH (alfa-LMWH) were investigated in 8 healthy volunteers after single subcutaneous administrations of 7,500, 15,000 and 30,000 anti-XaU doses at weekly intervals. Anti-Xa and anti-IIa heparin activities were monitored together with aPTT, thrombin time, bleeding time and euglobulin lysis time. No relevant changes in bleeding time or major side-effects were ever recorded. A group of 26 patients submitted to gynaecological surgery were then investigated to determine the dosage schedule for prophylaxis of post-operative deep vein thrombosis. Two subgroups received daily subcutaneous doses of 7,500 and 15,000 anti-XaU alfa-LMWH respectively, beginning 2 h before surgery; the third subgroup received 5,000 IU calcium heparin three times daily over the seven postoperative days. The following tests were peri-operatively monitored: anti-Xa heparin activity, aPTT, PT, fibrinogen, Antithrombin III. No differences in intra-operative bleeding or side-effects were recorded. On the basis of the levels of anti-Xa heparin activity and the negligible effects on aPTT, the dose of 7500 anti-XaU was selected at single daily administration for thromboprophylaxis in gynecological surgery.