SummaryIn a prospective, randomized, open study 119 consecutive patients with phlebographically verified deep venous thrombosis (DVT) of the leg (36% distal and 64% proximal) were treated either with a low molecular weight heparin (Fragmin, Kabi-Vitrum) subcutaneously (120 anti-FXa U/kg) twice daily or standard heparin (SH) as continuous intravenous infusion (480 IU kg−1 day−1). The Fragmin doses were adjusted to achieve an anti-FXa activity of 0.2-0.4 U/ml before injection and not greater than 1.5 U/ml 4 h after the morning injection. The SH dose was modified to prolong the APTT 2-3 times.Repeat phlebography after 5-7 days showed improvement in 34/45 patients (76%) in the Fragmin group and in 30/49 patients (61%) in the SH group and progress in 2/45 (4%) and 3/49 (6%), respectively. The mean Marder scores decreased from 18.7 ± 12.1 to 15.7 ± 12.7 in the Fragmin group and from 16.9 ± 12.0 to 14.4 ± 11.8 in the SH group (ns). Two patients in the SH group and none in the Fragmin group had major bleedings.After 22 ± 7 months follow up 6 rethromboses had occurred in the SH group and 4 in the Fragmin group. Postthrombotic signs and symptoms were similar in both groups.We conclude that two daily sc Fragmin doses seem as effective and safe as continuous SH in the treatment of DVT of the leg.

SummaryIn order to study whether a low molecular weight heparin (LMWH) of mw 4000 D is effective in the treatment of deep venous thrombosis (DVT), patients with DVT verified by phlebography were randomized to treatment by continuous intravenous infusion of either unfractionated heparin (UFH) or LMWH. The initial dose was 240 U (anti F Xa)/kg/12 h. TTiis study (study I) was stopped because of major bleeding in 2 newly operated patients in the LMWH group after 27 patients had been treated. The heparin activity measured as F Xa inhibition assayed in retrospect, was found to be much higher in the LMWH group (mean 1.6-2.0 anti F Xa U/ml) than in the UFH group (mean 0.5-0.8 anti F Xa U/ml).A second study was therefore initiated in which the DVT patients were randomly given UFH (240 U/kg/12 h) or LMWH only 120 U (anti F Xa)/kg/12 h, as initial doses (study II). In this study 27 patients could be evaluated, the mean heparin activity still being higher in the LMWH group (0.9-1.2 anti F Xa U/ml) than in the UFH group (0.5-0.7 anti F Xa U/ml).A second phlebographic investigation showed progression of thrombus size in 3 (11%) of the UFH patients of studies I and II (n = 29) and improvement in 14 (48%). There was no progression in any LMWH patient, 6 (50%) had improved in study I and 10 (77%) in study II. The mean decrease of thrombus size score (according to Marder) during treatment did not differ between the 3 groups.Antithrombin III decreased significantly in the UFH group but not in the LMWH groups. Aminotransferases increased in all 3 groups. There was no difference in mean capillary bleeding time between the 3 treatment groups.Although this material is relatively small, our findings suggest that LMWH seems to be of similar effectivity as UFH.

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SummaryThe pharmacokinetics of a heparin fragment of low molecular weight (LMWH) of 4000-5000 D and unfractioned standard heparin (UFH) have been studied after i. v. injections of different doses and infusions in 8 humans.The heparin activity was significantly higher and the effect on APTT lower after LMWH fragment as compared to UFH in the same doses.The half-life of heparin activity was about 1 hr for UFH and about 2 hr for LMWH. LMWH was found to be eliminated according to first order kinetics and there were no signs of dose dependency.

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