Letter to the Editor
Editor, – Boehringer Ingelheim suggests an alternative title for the feature about dabigatran (Aust Prescr 2012;35:64-5) – Medicinal mishap: Always read the product information before prescribing.
Given the case history of the elderly woman with nephropathy (creatinine clearance (CrCl) 29 mL/min), she should clearly not have been prescribed dabigatran. This serves to reinforce the need for appropriate patient selection consistent with the approved product information which includes the contraindication ‘severe renal impairment (CrCl<30 mL/min)’.
Prescribers should always read the product information before prescribing, regardless of whether a drug is new or old. As the sponsor for dabigatran, we are concerned the authors of this article did not include the dabigatran product information as a reference. The product information provides information pertinent to many of the issues raised in this case history.
On presentation to hospital, the patient was reported as having an INR of 2.5. As the authors mention later in the article, interpretation of an INR 2–3 weeks after starting dabigatran is meaningless. This information is provided in the product information. Further, and very importantly, when switching from warfarin to dabigatran, prescribers should only commence dabigatran once the INR is under 2. It is not clear whether this was confirmed in this clinical scenario.
The authors quote the Queensland Health guidelines for managing patients on dabigatran who present to hospital.1 These recommendations appear broadly consistent with the product information for dabigatran. Interventions recommended for the reversal of moderate-to-severe or life-threatening bleeding by the Queensland Health document and the product information include platelets, oral charcoal, recombinant factor VIIa, activated prothrombin complex concentrates (for example, factor eight inhibitor bypassing activity FEIBA), haemodialysis and charcoal haemofiltration. These were not used in this case.
Lastly, the authors incorrectly assert ‘Currently, no assay of dabigatran’s effect on coagulation is available’. A direct thrombin inhibitor assay (Hemoclot) is commercially available in Australia for assessing the anticoagulant activity of dabigatran.2
Medical affairs manager
North Ryde, NSW
- Safe and Quality Use of Medicines and the Anticoagulant Working Party. Guidelines for managing patients on dabigatran (Pradaxa) who present to hospital. Queensland Health. 2011. www.health.qld.gov.au/qhcss/mapsu/documents/ dabigatran_info.pdf [cited 2012 Jul 6]
- Stangier J, Feuring M. Using the HEMOCLOT direct thrombin inhibitor assay to determine plasma concentrations of dabigatran. Blood Coagul Fibrinolysis 2012;23:138-43.
- van Ryn J, Baruch L, Clemens A. Interpretation of point- of-care INR results in patients treated with dabigatran. Am J Med 2012;125:417-20.
- Eerenberg E, Kamphuisen P, Sijpkens M, Meijers JC, Buller HR, Levi M. Reversal of rivaroxaban and dabigatran by prothrombin complex concentrate. Circulation 2011;124:1573-9.
- Kaatz S, Kouides P, Garcia D, Spyropolous AC, Crowther M, Douketis JD, et al. Guidance on the emergent reversal of oral thrombin and factor Xa inhibitors. Am J Hematol 2012;87 Suppl 1:S141-5. DOI: 10.1002/ajh.23202.
- Cotton B, McCarthy J, Holcomb J. More on acutely injured patients receiving dabigatran [author reply]. N Engl J Med 2012;366:864.
- Martin JH, Coory MD. New medicines – urgent need to assess outcomes in special groups. Med J Aust 2012;196:433.