What is the prophylactic dose of Clexane (enoxaparin) for an immobile patient?

Prophylactic Enoxaparin Dosing for Immobile Patients

For immobile hospitalized medical patients, administer enoxaparin 40 mg subcutaneously once daily, continuing for the duration of hospitalization or until the patient is fully ambulatory. 1, 2

Standard Prophylactic Dosing

• Enoxaparin 40 mg subcutaneously once daily is the established prophylactic dose for hospitalized medical patients at risk for venous thromboembolism 1, 2
• Continue prophylaxis throughout the hospital stay or until the patient regains full mobility 1, 2
• This fixed-dose regimen has demonstrated significant efficacy, reducing VTE incidence from 14.9% (placebo) to 5.5% in immobilized medical patients 3

Special Population Dose Adjustments

Severe Renal Impairment (CrCl <30 mL/min)

• Reduce dose to 30 mg subcutaneously once daily in patients with severe renal failure 1, 2, 4
• Enoxaparin clearance decreases by 44% in severe renal impairment, leading to drug accumulation and increased bleeding risk 4, 5
• Standard dosing without adjustment increases major bleeding risk nearly 4-fold (8.3% vs 2.4%) 4
• Consider switching to unfractionated heparin as the preferred alternative, which requires no renal dose adjustment 4

Obesity (BMI >30 kg/m²)

• Consider intermediate dosing at 40 mg subcutaneously every 12 hours or weight-based dosing at 0.5 mg/kg subcutaneously every 12 hours 1, 2
• Fixed-dose enoxaparin may result in sub-prophylactic anti-Xa levels in morbidly obese patients 6, 7
• Weight-based dosing at 0.5 mg/kg once daily achieves appropriate anti-Xa levels (mean 0.25 units/mL) without excessive anticoagulation in morbidly obese patients 6

Underweight Patients (<50 kg)

• Consider reducing to 30 mg subcutaneously once daily in patients weighing ≤50 kg, particularly if concurrent renal impairment exists 4, 8
• Both reduced (30 mg) and standard (40 mg) dosing appear effective in underweight patients, though neither shows clear superiority 8
• Anti-Xa levels inversely correlate with weight, making lower-weight patients susceptible to excessive anticoagulation 7

Critical Timing Considerations with Neuraxial Anesthesia

• Wait at least 12 hours after neuraxial block placement before administering the first prophylactic dose of enoxaparin 40 mg once daily 1, 2
• Wait at least 4 hours after epidural catheter removal before giving enoxaparin 1, 2
• For intermediate dosing (40 mg every 12 hours), wait at least 24 hours after neuraxial block before starting therapy 1
• Prophylactic-dose unfractionated heparin can be started as early as 1 hour after catheter removal, making it preferable when earlier anticoagulation is needed 1

Monitoring Recommendations

• Routine anti-Xa monitoring is not necessary for most patients on standard prophylactic dosing 2
• Monitor anti-Xa levels in patients with severe renal impairment (CrCl <30 mL/min) receiving prolonged therapy, targeting 0.5-1.5 IU/mL 2, 4
• Check anti-Xa levels 4 hours after administration, only after 3-4 doses have been given 2, 4
• Monitor platelet counts every 2-3 days from day 4 to day 14 to screen for heparin-induced thrombocytopenia 2

Common Pitfalls to Avoid

• Never use standard 40 mg dosing in severe renal impairment without dose reduction—this dramatically increases bleeding risk 4, 5
• Do not administer enoxaparin within 12 hours of neuraxial anesthesia—this increases spinal hematoma risk 1, 2
• Avoid switching between enoxaparin and unfractionated heparin during the same hospitalization—this increases bleeding complications 4
• Do not assume fixed dosing is adequate in morbidly obese patients—consider weight-based or intermediate dosing strategies 1, 2, 6
• Recognize that near-normal serum creatinine may mask reduced creatinine clearance in elderly, female, or low-body-weight patients—always calculate CrCl using the Cockcroft-Gault formula 4

Advantages Over Unfractionated Heparin

• Superior bioavailability and longer half-life allowing once-daily dosing 2
• More predictable anticoagulation effect without need for routine monitoring 2
• Lower risk of heparin-induced thrombocytopenia 2
• Reduced bleeding risk compared to unfractionated heparin in medical patients 3