New anticoagulant gets mixed resultsBMJ 2007; 335 doi: https://doi.org/10.1136/bmj.335.7620.586 (Published 20 September 2007) Cite this as: BMJ 2007;335:586
Idraparinux is a new anticoagulant that inhibits activated factor X. It has a long half life and can be given just once a week, by subcutaneous injection. But is it as good as standard anticoagulants at preventing recurrent venous thromboembolism⇑?
In two parallel trials, the new drug worked well for patients with deep vein thrombosis but not so well for those with a pulmonary embolus.
Both trials compared idraparinux with the usual regimen of intravenous heparin followed by warfarin for three to six months. Among 2904 patients with deep vein thrombosis, risk of a recurrence was about the same in both groups (odds ratio 0.98 for idraparinux, 95% CI 0.63 to 1.50 at three months), but idraparinux caused fewer clinically relevant bleeding complications. Among 2215 patients with pulmonary embolus, idraparinux was associated with a significantly higher rate of recurrence at both three and six months (2.14; 1.21 to 3.78 at three months). It was also associated with a significant excess of deaths (6.4% v 4.4% at six months, P=0.04), including deaths from pulmonary embolus.
Bleeding was less of a problem for patients taking idraparinux in both trials. But the authors warn that the new agent has a very long half life, and there's no antidote when bleeding does occur.