Anticoagulant
Anticoagulants are "agents that prevent blood clotting".[1] They may be used to prevent embolism and thrombosis.
Vitamin K antagonists
Warfarin
Warfarin is a commonly used oral anticoagulant that interferes with the Vitamin K dependent coagulation co-factors. Because of complexities in its administration, newer oral anticoagulants such as dabigatran (a direct inhibitor of thrombin) and rivaroxaban (an inhibitor of factor Xa) are being researched.[2]
Heparins
Unfractionated heparin
Details of the usage of heparin are available in clinical practice guidelines by the American College of Chest Physicians[3]:
Heparin dose may also be adjusted by using an anti-Xa assay to measure heparin function, which is related to heparin levels. The goal heparin level is 0.3 to 0.7 U/mL for unfractionated heparin but a higher level for low molecular weight heparin.[4][5][6]
Low molecular weight heparin
| Prophylaxis dose | Full dose | Comments | |
|---|---|---|---|
| Enoxiparin (Lovenox) |
Either: 30 mg twice daily 40 mg once daily |
Either: 1 mg/kg/dose every 12 hours 1.5 mg/kg once daily more information is at Enoxaparin |
|
| Dalteparin (Framin) |
After loading, 2500 to 5000 int. units daily | 150 int. units/kg up to 18,000 int. units) once daily dosing is complicated and more information is at DailyMed |
If creatinine clearance is less then 30 mL/minute, monitor anti-Xa levels |
The last dose of low molecular weight heparin prior to coronary artery bypass surgery should occur 24 hours before the procedure in order to prevent high residual anti-Xa levels.[7]
Direct thrombin inhibitors
Direct thrombin inhibitors bind directly to thrombin[8] and are used for heparin-induced thrombocytopenia and during percutaneous coronary interventions.[9]
- Argatroban is for treating heparin-induced thrombocytopenia (HIT)
- Bivalirudin is a recombinant protein
- Dabigatran is given orally.
- Desirudin
- Hirudin is a recombinant protein for treating heparin-induced thrombocytopenia (HIT)
- Lepirudin
- Ximelagatran is a recombinant protein that is an oral direct thrombin inhibitor
Factor Xa inhibitors
- Fondaparinux can prevent embolism and thrombosis during perioperative care according to randomized controlled trials of hip fracture surgery[10].
- Idraparinux is a synthetic derivative of heparin that has a long half life that allows once-weekly dosage. A randomized controlled trial compared idraparinux to warfarin and found that idraparinux is equivalent for deep venous thrombosis but is inferior for pulmonary embolism.[11]
- Rivaroxaban can be given orally. It can prevent embolism and thrombosis during perioperative care according to randomized controlled trials of two weeks of therapy after knee arthoplasty[12] or 5 weeks of therapy after hip arthroplasty.[13][14]
Warfarin combined with heparin
Warfarin combined with heparin did not benefit survivors of acute myocardial infarction in a randomized controlled trial.[15]
Warfarin combined with heparin reduced events, but increased bleeding, among survivors of acute myocardial infarction in a randomized controlled trial.[16]
Adverse effects
The risk of bleeding when heparin is used in patients with acute coronary syndrome can be estimated with a clinical prediction rule (http://www.crusadebleedingscore.org/).
Bleeding is more likely when more than one antithrombotic is used.[17]
References
- ↑ Anonymous (2024), Anticoagulants (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ (2009) "Anticoagulation with dabigatran or rivaroxaban.". Drug Ther Bull 47 (10): 116-20. DOI:10.1136/dtb.2009.09.0041. PMID 19809086. Research Blogging.
- ↑ Hirsh J, Raschke R (2004). "Heparin and low-molecular-weight heparin: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy". Chest 126 (3 Suppl): 188S-203S. DOI:10.1378/chest.126.3_suppl.188S. PMID 15383472. Research Blogging.
- ↑ Rosborough TK, Shepherd MF (June 2004). "Achieving target antifactor Xa activity with a heparin protocol based on sex, age, height, and weight". Pharmacotherapy 24 (6): 713–9. DOI:10.1592/phco.24.8.713.36067. PMID 15222660. Research Blogging.
- ↑ Rosborough TK (June 1999). "Monitoring unfractionated heparin therapy with antifactor Xa activity results in fewer monitoring tests and dosage changes than monitoring with the activated partial thromboplastin time". Pharmacotherapy 19 (6): 760–6. PMID 10391423. [e]
- ↑ Levine MN, Hirsh J, Gent M, et al. (January 1994). "A randomized trial comparing activated thromboplastin time with heparin assay in patients with acute venous thromboembolism requiring large daily doses of heparin". Arch. Intern. Med. 154 (1): 49–56. PMID 8267489. [e]
- ↑ Whitlock RP, Crowther MA, Warkentin TE, Blackall MH, Farrokhyar F, Teoh KH (2007). "Warfarin cessation before cardiopulmonary bypass: lessons learned from a randomized controlled trial of oral vitamin K". Ann. Thorac. Surg. 84 (1): 103–8. DOI:10.1016/j.athoracsur.2007.03.014. PMID 17588394. Research Blogging.
- ↑ Di Nisio M, Middeldorp S, Büller HR (2005). "Direct thrombin inhibitors". N. Engl. J. Med. 353 (10): 1028–40. DOI:10.1056/NEJMra044440. PMID 16148288. Research Blogging.
- ↑ Baetz BE, Spinler SA (2008). "Dabigatran etexilate: an oral direct thrombin inhibitor for prophylaxis and treatment of thromboembolic diseases.". Pharmacotherapy 28 (11): 1354-73. DOI:10.1592/phco.28.11.1354. PMID 18956996. Research Blogging.
- ↑ Eriksson BI, Bauer KA, Lassen MR, Turpie AG (November 2001). "Fondaparinux compared with enoxaparin for the prevention of venous thromboembolism after hip-fracture surgery". The New England journal of medicine 345 (18): 1298–304. PMID 11794148. [e]
- ↑ Buller HR, Cohen AT, Davidson B, et al (2007). "Idraparinux versus standard therapy for venous thromboembolic disease". N. Engl. J. Med. 357 (11): 1094–104. DOI:10.1056/NEJMoa064247. PMID 17855670. Research Blogging.
- ↑ Lassen MR, Ageno W, Borris LC, et al (June 2008). "Rivaroxaban versus enoxaparin for thromboprophylaxis after total knee arthroplasty". The New England journal of medicine 358 (26): 2776–86. DOI:10.1056/NEJMoa076016. PMID 18579812. Research Blogging.
- ↑ Eriksson BI, Borris LC, Friedman RJ, et al (June 2008). "Rivaroxaban versus enoxaparin for thromboprophylaxis after hip arthroplasty". The New England journal of medicine 358 (26): 2765–75. DOI:10.1056/NEJMoa0800374. PMID 18579811. Research Blogging.
- ↑ Kakkar AK, Brenner B, Dahl OE, et al (July 2008). "Extended duration rivaroxaban versus short-term enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a double-blind, randomised controlled trial". Lancet 372 (9632): 31–9. DOI:10.1016/S0140-6736(08)60880-6. PMID 18582928. Research Blogging.
- ↑ Fiore LD, Ezekowitz MD, Brophy MT, Lu D, Sacco J, Peduzzi P (2002). "Department of Veterans Affairs Cooperative Studies Program Clinical Trial comparing combined warfarin and aspirin with aspirin alone in survivors of acute myocardial infarction: primary results of the CHAMP study". Circulation 105 (5): 557–63. PMID 11827919. [e]
- ↑ Hurlen M, Abdelnoor M, Smith P, Erikssen J, Arnesen H (2002). "Warfarin, aspirin, or both after myocardial infarction". N. Engl. J. Med. 347 (13): 969–74. DOI:10.1056/NEJMoa020496. PMID 12324552. Research Blogging.
- ↑ Sørensen R, Hansen ML, Abildstrom SZ, Hvelplund A, Andersson C, Jørgensen C et al. (2009). "Risk of bleeding in patients with acute myocardial infarction treated with different combinations of aspirin, clopidogrel, and vitamin K antagonists in Denmark: a retrospective analysis of nationwide registry data.". Lancet 374 (9706): 1967-74. DOI:10.1016/S0140-6736(09)61751-7. PMID 20006130. Research Blogging.