What is the recommended dose of Enoxoprine (a beta-blocker) for a patient with severe impaired renal function, indicated by an estimated Glomerular Filtration Rate (eGFR) of 19?

Enoxaparin Dosing in Severe Renal Impairment (eGFR 19)

For a patient with an eGFR of 19 mL/min/1.73 m², reduce enoxaparin to 1 mg/kg subcutaneously once daily for therapeutic anticoagulation, or 30 mg subcutaneously once daily for prophylactic anticoagulation. 1, 2

Therapeutic Anticoagulation Dosing

The standard therapeutic dose must be reduced by 50% in severe renal impairment (eGFR <30 mL/min). 1, 2

• Administer 1 mg/kg subcutaneously once daily (not the standard twice-daily dosing used in normal renal function). 1, 2
• This represents a 50% reduction in total daily dose compared to the standard 1 mg/kg every 12 hours regimen. 2
• Enoxaparin clearance decreases by 44% in severe renal impairment, leading to significant drug accumulation with standard dosing. 1, 3
• Without dose adjustment, major bleeding risk increases nearly 4-fold (8.3% vs 2.4%; OR 3.88). 2

Prophylactic Anticoagulation Dosing

For VTE prophylaxis, reduce to 30 mg subcutaneously once daily. 1

• This is the only FDA-approved prophylactic dosing recommendation for severe renal impairment among all low-molecular-weight heparins. 1
• Standard prophylactic dosing of 40 mg once daily should not be used at this level of renal function. 1

Critical Pharmacokinetic Rationale

The dose reduction is mandatory due to predictable drug accumulation:

• Anti-Xa clearance is reduced by 39% in patients with CrCl <30 mL/min. 2
• Drug exposure increases by 35% with repeated dosing in severe renal impairment. 2
• A strong linear correlation exists between creatinine clearance and enoxaparin clearance (R=0.85, P<0.001). 2
• Patients with CrCl <30 mL/min have 2.25 times higher odds of major bleeding (OR 2.25,95% CI 1.19-4.27) compared to those with normal renal function when receiving standard doses. 2

Monitoring Requirements

Monitor anti-Xa levels in all patients with eGFR <30 mL/min receiving prolonged treatment. 1

• Check peak anti-Xa levels 4 hours after administration, only after 3-4 doses have been given. 1
• Target anti-Xa ranges: 0.5-1.0 IU/mL for twice-daily dosing, >1.0 IU/mL for once-daily dosing. 1
• For therapeutic anticoagulation, the target range is 0.5-1.5 IU/mL. 2

Preferred Alternative: Unfractionated Heparin

Strongly consider switching to unfractionated heparin (UFH) as the preferred anticoagulant in severe renal impairment. 1, 2

• UFH undergoes reticuloendothelial clearance, not renal clearance, eliminating accumulation concerns. 2
• Dosing: 60 IU/kg IV bolus (maximum 4000 U) followed by 12 IU/kg/hour infusion (maximum 1000 U/hour). 1, 2
• Adjust infusion to maintain aPTT at 1.5-2.0 times control (60-80 seconds). 1, 2
• UFH is particularly preferred for unstable patients or those requiring therapeutic anticoagulation. 2

Contraindicated Alternatives

Never use fondaparinux in patients with eGFR <30 mL/min—it is absolutely contraindicated. 1, 2

• Fondaparinux should never be used in dialysis patients or those with severe renal impairment. 1

Additional High-Risk Considerations

Be aware of compounding risk factors that further increase bleeding risk:

• Advanced age (≥75 years): Avoid the initial 30 mg IV bolus in elderly patients; use only subcutaneous dosing with heightened vigilance. 2
• Low body weight (<55 kg): Both underweight status and severe renal impairment independently increase bleeding risk; use 30 mg once daily for prophylaxis and monitor anti-Xa levels closely. 2
• Hemodialysis patients: Administer the daily enoxaparin dose 6-8 hours after hemodialysis completion to minimize bleeding risk at the vascular access site. 2

Critical Safety Warning

Never switch between enoxaparin and unfractionated heparin mid-treatment, as this significantly increases bleeding risk. 1, 2