MPA | Pharmacy News

by Karl Renius, Pharm.D., BCPS, staff pharmacist, Crittenton Hospital, MSHP IT Task Force member

Approval of direct oral anticoagulants (DOACs) has shaken up anticoagulation treatment, which has been up until recently predominantly low-molecular weight heparins (LMWH) and vitamin-k antagonist (VKA) therapy. The American College of Chest Physicians has issued a 2016 guideline on the treatment of venous thromboembolism (VTE) disease, in an update from the last edition in 2012. The new guidelines are available in full on the CHEST website.1

While many of the guideline recommendations remain the same, there is a major change in terms of preferred anticoagulants. For VTE in patients without cancer, the CHEST guidelines now recommend dabigatran, rivaroxaban, apixaban or edoxaban over VKA therapy for initial and long-term treatment (grade 2B). The guidelines specifically state that no single DOAC is preferred over the others. If DOACs are not used, the guidelines recommend VKA therapy over LMWH. The guidelines state that the DOACs are as effective as VKA therapy with the benefits of reduced risk of bleeding and increased convenience. Following completion of anticoagulant therapy in patients with unprovoked VTE, the guidelines also recommend initiating aspirin to prevent recurrent VTE in patients without a contraindication to aspirin.1

For cancer-associated thrombosis, LMWH remains the recommended first-line option. The guideline included the recently published CATCH trial (which did not demonstrate a difference in recurrent VTE in patients who received tinzaparin or warfarin for six months) in its analysis of trials that compared LMWH versus VKA in patients with cancer-related thrombosis.2 The relative risk of recurrent VTE with LMWH versus VKA therapy in this patient population is stated as 0.59 (95% CI: 0.44-0.78), still favoring the use of LMWH.

Some additional changes to the guideline include:1

  • In subsegmental pulmonary embolism without deep venous thrombus (DVT) and a low risk for recurrent VTE, clinical surveillance is preferred over anticoagulation
  • A recommendation against inferior vena cava filters for VTE treated with anticoagulants
  • A recommendation against use of compression stockings to prevent post-thrombotic syndrome in patients with DVT

As a side note, there is currently no consensus on an acronym for the new class of anticoagulants. While this article refers to them as DOACs, they have also been called target-specific oral anticoagulants (TSOACs) and novel/new oral anticoagulants (NOACs). The 2016 CHEST guideline for treatment of VTE uses the term NOACs. However, the Institute for Safe Medication Practices recommends against using NOACs as an acronym.3 The recommendation is because NOAC has been interpreted in practice as NoAC, or No AntiCoagulation. To avoid the potential for accidental discontinuation of anticoagulation, use of NOAC to refer to these medications should be discouraged.

DOACs have some major pharmacologic advantages over VKA’s, including predictable pharmacokinetics, rapid onset and elimination, fewer drug interactions, and no requirement for routine monitoring. However, use of these agents is limited by cost and complicated by altered dosing regimens depending on renal function and indication. Though pharmacists may see decreased involvement in routine monitoring of anticoagulation due to the shift to DOACs, there is still plenty of room for pharmacist involvement to ensure quality of care.

References:

1.         Kearon C, Akl EA, Ornelas J, Blaivas A, Jimenez D, Bounameaux H, et al. Antithrombotic therapy for VTE disease: Chest guideline. Chest [Internet]. 2016 Jan 7 [cited 2016 Jan 8]; Available from: http://dx.doi.org/10.1016/j.chest.2015.11.026

2.         Lee AYY, Kamphuisen PW, Meyer G, Bauersachs R, Janas MS, Jarner MF, et al. Tinzaparin vs Warfarin for Treatment of Acute Venous Thromboembolism in Patients With Active Cancer: A Randomized Clinical Trial. JAMA. 2015 Aug 18;314(7):677–86.

3.            ISMP’s List of Error-Prone Abbreviations, Symbols, and Dose Designations. Institute for Safe Medication Practice; 2015 [cited 2016 Jan 21]. Available from: http://www.ismp.org/tools/errorproneabbreviations.pdf

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