MedWire (is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited.Protamine, the only registered antidote of unfractionated heparin (UFH), may produce a number of adverse effects, such as anaphylactic shock or serious hypotension.

Large-scale production processes are required before clinical trials can be carried out. However, they note that at present, the antithrombin variant can only be produced on a small scale. 'These results clearly demonstrate that AT-N135Q-Pro394 can reverse the anticoagulant activity of fondaparinux and thus could be used as an antidote for this drug ,' write the researchers in the journal Blood. The researchers observed a similar antidote effect in vivo, as administration of AT-N135Q-Pro394 to mice treated with fondaparinux at five times the curative dose neutralized 86% of the anti-Xa activity within 5 minutes. In additon, AT-N135Q-Pro394 decreased UFH and LMWH anticoagulant activity by 76% in overdosed plasma, indicating that it acts as a potent antidote to all heparin-like anticoagulants. Moreover, the antidote effect was dose-dependant. They found that AT-N135Q-Pro394, at a concentration equal to the endogenous plasma antithrombin concentration, significantly reduced the fondaparinux concentration from 3.0 to 1.23 mg/l - a concentration equivalent to that used for curative treatment.

To test the antidote's ability to reverse fondaparinux overdose, they added increasing concentrations of AT-N135Q-Pro394 to plasma spiked with approximately three times the maximal curative dose of fondaparinux.

What is the antidote for heparin