When should the heparin (unfractionated heparin) drip be stopped when starting Lovenox (enoxaparin)?

From the FDA Drug Label

2.8 Converting to Oral Anticoagulants other than Warfarin For patients currently receiving intravenous heparin, stop intravenous infusion of heparin sodium immediately after administering the first dose of oral anticoagulant;

The heparin drip should be stopped immediately after administering the first dose of Lovenox (enoxaparin). 1 Key points:

• Stop heparin infusion immediately after the first dose of Lovenox.
• No tapering of heparin is required when converting to Lovenox.

From the Research

When transitioning from a heparin (unfractionated heparin) drip to Lovenox (enoxaparin), the heparin infusion should be discontinued at the time the first dose of Lovenox is administered. There is no need for an overlap period between these medications. For patients receiving therapeutic heparin, the first dose of Lovenox (typically 1 mg/kg twice daily or 1.5 mg/kg once daily) should be given immediately after stopping the heparin infusion. For prophylactic dosing, standard Lovenox doses (30-40 mg twice or once daily) can be started immediately upon heparin discontinuation. This immediate transition is possible because Lovenox has a rapid onset of action, reaching peak anti-Xa activity within 3-5 hours after subcutaneous injection. Since both medications work as anticoagulants by inhibiting factors in the coagulation cascade (though through slightly different mechanisms), administering them simultaneously could significantly increase bleeding risk without providing additional therapeutic benefit. Renal function should be assessed before starting Lovenox as dose adjustments are needed for patients with creatinine clearance below 30 mL/min, and Lovenox is contraindicated in severe renal impairment, as supported by studies such as 2. Key considerations include:

• The need for dose adjustment in patients with renal insufficiency, with enoxaparin and nadroparin adjusted to 50-65% and 75-85% of the original dose for patients with a creatinine clearance (CrCL) of <30 ml/min and 30-60 ml/min, respectively, as recommended by 2.
• The importance of monitoring anti-Xa levels, particularly in patients with renal insufficiency, to minimize the risk of bleeding complications, as highlighted by 3 and 2.
• The preference for trough concentration anti-Xa monitoring over peak monitoring, aiming at a maximum concentration of 0.4 IU/mL for once-daily dosed tinzaparin and 0.5 IU/mL for twice-daily dosed enoxaparin and nadroparin, as suggested by 2. Overall, the decision to transition from heparin to Lovenox should be guided by the patient's individual clinical needs and renal function, with careful consideration of the potential risks and benefits of each medication, as informed by the most recent and highest quality evidence, such as 2.