Fondaparinux and HIT

Q: Fondaparinux like other low molecular weight heparins (LMWH) may cause heparin-induced thrombocytopenia (HIT)? 

A) True 

B) False

Answer: B

Fondaparinux is one of the unique low molecular weight heparins which does not cause HIT. It is an indirect inhibitor of factor Xa, but does not inhibit thrombin and does not interact with platelets or platelet factor 4 (PF-4). Also, Fondaparinux is 100 percent bioavailable after SQ administration. 

Despite these advantages, Fondaparinux never gets much popular in US hospitals due to various reasons. It has a very pretty long half-life of 15-17 hours, and in case of bleeding, there is no specific antidote. It takes three to five half-lives which translates to two to four days till all bleeding risks subside. Also, it gets eliminated via kidney, and renal insufficiency is widely common in ICU patients.

#pharmacology

#hematology

References:

1. Linkins LA, Hu G, Warkentin TE. Systematic review of fondaparinux for heparin-induced thrombocytopenia: When there are no randomized controlled trials. Res Pract Thromb Haemost. 2018 Aug 9;2(4):678-683. doi: 10.1002/rth2.12145. PMID: 30349886; PMCID: PMC6178656. 

2. Warkentin TE, Cook RJ, Marder VJ, et al. Anti-platelet factor 4/heparin antibodies in orthopedic surgery patients receiving antithrombotic prophylaxis with fondaparinux or enoxaparin. Blood 2005; 106:3791. 

3. Warkentin TE. Fondaparinux: does it cause HIT? Can it treat HIT? Expert Rev Hematol. 2010 Oct;3(5):567-81. doi: 10.1586/ehm.10.54. PMID: 21083474.