Hartmann et al presented important principles of drug therapy in patients with renal failure. However, concrete individual recommendations regarding anticoagulation given in the article have to be corrected. Uremic bleeding disorder simultaneously combines bleeding risk with procoagulatory activity and increased risk of thrombosis. Especially patients with severe renal failure (GFR <30 mL/min) present with increased cardiovascular morbidity and mortality. Then any type of anticoagulation incurs an increased risk of hemorrhage and requires critical selection of the anticoagulatory drug using appropriate dosage and laboratory monitoring. Patients with severe renal failure are usually not represented in study populations, even for the newer oral anticoagulants.
Low molecular weight heparins have notably improved the options for anticoagulation compared with unfractionated heparin and vitamin K antagonists. The articles' conclusion, not to use enoxaparin in patients with GFR <60 mL/min, is wrong. Enoxaparin is the low molecular weight heparin that has been most extensively studied for all stages of renal failure and is explicitly licensed for a GFR<30 mL/min with clear recommendations how to adapt the dosage. Suggesting tinzaparin as an alternative in this context is not reasonable.
As assessed by permeation chromatography, enoxaparin is the low molecular weight heparin with the highest content of defined oligomers, whereas tinzaparin to a substantial extent resembles unfractionated heparin (1). The wording of accumulation “in a deep compartment” in the article remains an enigma. In acute coronary syndrome, using enoxaparin yields a mortality advantage without increasing hemorrhage-associated complications, even in severe renal failure (2, 3). Mahe et al did not observe more hemorrhagic complications in the referenced study for enoxaparin than for tinzaparin, although the dosage of enoxaparin had not been adequately adjusted in some cases and not adapted according to laboratory monitoring.
The IRIS study investigated tinzaparin versus unfractionated heparin in venous thrombosis and found a higher mortality for tinzaparin in patients with renal failure who were older than 70.
Footnotes
Conflict of interest statement
Professor Klingel has received study funding from Asahi Kasei Kuraray Medical Tokyo and Sanofi-Aventis Berlin.
References
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