Unlike unfractionated heparin (UFH), the low-molecular-weight heparin enoxaparin (Lovenox) is excreted mainly by the kidneys. To determine whether this characteristic heightens bleeding risk in patients with renal insufficiency, researchers in Connecticut compared bleeding rates with enoxaparin and UFH in a retrospective study of 620 hospitalized patients with renal insufficiency.
All patients received full therapeutic doses of enoxaparin or UFH. Renal insufficiency was mild (glomerular filtration rate, 41-60 mL/minute) in 50%, moderate (21-40 mL/minute) in 34%, and severe (≤20 mL/minute) in 16%. In analyses that were adjusted for potential confounders, rates of major bleeding did not differ significantly between enoxaparin and UFH recipients, regardless of the degree of renal impairment. However, minor bleeding was significantly more common with enoxaparin than with UFH in the subgroup with severe impairment (rate, 68 vs. 27 minor bleeds per 1000 person-days). Overall, 10% of patients had major bleeding, and 14% had minor bleeding.
In this nonrandomized, retrospective study, minor (but not major) bleeding was significantly more common with enoxaparin than with UFH among patients with severe renal insufficiency. In December 2003, the official prescribing information for enoxaparin changed to reflect data from new manufacturer-sponsored research on enoxaparin pharmacokinetics. For patients with creatinine clearance <30 mL/minute, the new prescribing information recommends reduced doses of 30 mg once daily for DVT prophylaxis and 1 mg/kg once daily for treatment of venous thromboembolism, unstable angina, and non-Q-wave myocardial infarction. Standard doses still are recommended for patients with milder degrees of renal impairment.