 UFH is the only antidote-reversible anticoagulant currently approved for use. However, UFH has significant limitations. First, heparin has complex pharmacokinetics that make the predictability of its use challenging Granger et al., 1996. Second, the dose predictability of its antidote, protamine, is challenging, and there are serious side effects associated with its use Carr and Silverman, 1999; Welsby et al., 2005. Finally, heparin can induce thrombocytopenia HIT and thrombocytopenia with thrombosis HITT Warkentin, 2005; Warkentin and Greinacher, 2004. 