Anticoagulation therapy in acute deep venous thrombosis (DVT)
• Unfractionated heparin (UFH) should be given as 80 U/kg loading dose followed by 18 U/kg/h maintenance dose, as intravenous infusion achieves target aPTT more rapidly than fixed-dose regimens.
• The aPTT should not be followed while using UFH in patients with abnormal baseline aPTT (such as lupus anticoagulant) or in patients require unusually higher doses of heparin (such as antithrombin deficiency). In these situations, the anti-factor 10a assay should be used instead.
• Enoxaparin can be given either once-daily regimen (1.5 mg/kg/d) or twice-daily regimen (1 mg/kg/12 h).
• Monitoring enoxaparin is not required except in obese, pediatric, pregnant, or patients with renal insufficiency. In these situations, the anti-factor 10a level should be be measured 4 hours after injection, and it should be between 0.5 and 1.0 IU/mL for twice-daily regimen or more than 1.0 IU/mL for once-daily regimen.
• Fondaparinux is an indirect factor 10a inhibitor, given SC once daily at dose of 5 mg for body weight less than 50 kg, 7.5 mg for body weight between 50 and 100, and 10 mg for more than 100 kg.
• Fondaparinux is contraindicated in severe renal impairment (CrCl less than 30 mL/min.) or bacterial endocarditis.