I’m a registrar in an ICU at Menofyia University, Menofyia, Egypt. We have been thinking about using the new drug, Fondaparinux. Could you please give me more details about the drug, when to monitor its efficacy (all patients or high risk only?) and how do you use the anti-factor Xa assay; i. e. the kits and the frequency of monitoring? is it a daily blood sample in the case of the prophylactic dose (2.5 mg)? Where could I find these kits? could you give me the address of any specialized company in coagulation monitoring. Hagar
Dear Dr. Hagar, thank you for your question. I’ve seen several clinical trial reports that indicate Fondaparinux is at least as effective and safe as low molecular weight heparin.
I am providing a link to Hirsh J, Bauer KA, Donati MB, et al. Parenteral anticoagulants: American College of Chest Physicians evidence-based clinical practice guidelines (8th Edition). Chest 2008;133:141S-159S, which provides Fondaparinux dosing and monitoring details in section 2.3. Fondaparinux may be administered for prophylaxis subcutaneously in fixed doses of 2.5 mg once a day without laboratory monitoring. Laboratory monitoring using the anti-Xa assay is recommended during pregnancy, cancer, renal insufficiency, and in people who are morbidly obese or underweight. It must be monitored in patients whose creatinine clearance is below 50 mL/minute and is contraindicated in those below 30 mL/min. There are no established intervals for monitoring, I might suggest testing once at the onset of therapy and again after each dosage change, and I invite comments from others who monitor Fondaparinux regularly.
Current anti-Xa kits use low molecular weight heparin for their reference standard. Most experts agree this cannot be generalized to Fondaparinux monitoring; instead use Fondaparinux as the standard. The anti-Xa assay may be ordered from Hyphen BioMed,Instrumentation Laboratory, who offer a new liquid heparin kit, or Diagnostica Stago, and their representatives will assist you in modifying the kit by using Fondaparinux as the reference standard. You may also wish to access my audio module #22 for further details.