**Author details**

• age < 75 years, 30 mg i.v. bolus immediately prior to thrombolysis followed within 15 minutes by 1 mg/kg subcutaneously every 12 hours (each dose should not exceed 100 mg); • age > 75 years, 0.75 mg/kg subcutaneously every 12 hours (each dose should not exceed

Intravenous anticoagulation with UFHs in addition to antiplatelet therapy is recommended for all patients undergoing primary percutaneous coronary intervention (PCI). Anticoagulant therapy is selected according to patient's ischemic and bleeding risks (70–100 units/kg i.v. bolus or 50–70 units/kg i.v. bolus with GPIIb/IIIa inhibitor). Bivalirudin or intravenous enoxa-

Safe and effective use of heparin requires maintaining a delicate balance: dosing low enough to minimize the risk of bleeding, yet high enough to treat or prevent thrombosis. Achieving a therapeutic level of heparin within 24 hours significantly reduces the risk for recurrent VTE [52]. However, non-protocol-driven practice achieves this outcome only 40% of the time [53]. Bleeding is the primary untoward effect of heparin. Major bleeding occurs in 1–5% of patients treated with intravenous heparin for venous thromboembolism [54]. The incidence of bleeding is somewhat less in patients treated with LMWH for this indication, although the risk of

Heparin-induced thrombocytopenia (platelet count <150,000/mL or a 50% decrease from the pre-treatment value) occurs in ~0.5% of medical patients 5–10 days after initiation of therapy with heparin [55]. Although the incidence may be lower, thrombocytopenia also occurs with LMWHs and fondaparinux and platelet counts should be monitored. Thrombotic complications that can be life-threatening or lead to amputation occur in about one-half of the affected heparin-treated patients and may precede the onset of thrombocytopenia. The incidence of heparin-induced thrombocytopenia and thrombosis is higher in surgical patients than in

Fondaparinux is a synthetic heparin-like compound that acts as indirect factor Xa inhibitor [50]. Idraparinux and idrabiotaparinux are second and third generation pentasaccharides

After subcutaneous administration, fondaparinux is cleared by kidneys and has an elimination half-life of 17 h in healthy volunteers and 29 h in patients with moderate renal insufficiency, and therefore, it is contraindicated in patients with severe renal insufficiency. In this specific condition, laboratory monitoring is performed with anti-Xa assay, aPTT, and PT [50]. Fondaparinux is approved as an alternative for heparin or LMWH in the initial treatment of VTE in conjunction with a vitamin K antagonist (VKA) and, in Europe, for ACS in patients for

75 mg in the first two administrations); • UFHs in patients with CrCl is <30 mL/min.

*3.1.6. Real-world safety aspects*

94 Anticoagulant Drugs

derived from fondaparinux.

whom PCI is not indicated [56].

parin (0.5 mg/kg i.v.) may be used as alternatives to UFH.

bleeding appears to increase with higher total daily doses of heparin.

medical patients. Women are twice as likely as men to develop this condition.

**3.2. Fondaparinux, idraparinux, and idrabiotaparinux**

Niccolò Lombardi, Giada Crescioli and Alfredo Vannacci\*

\*Address all correspondence to: alfredo.vannacci@unifi.it

Department of Neurosciences, Psychology, Drug Research and Child Health, Section of Pharmacology and Toxicology, University of Florence, Florence, Italy
