Warfarin (Coumadin®) is an oral anticoagulant, meaning that it is taken by mouth to prevent the formation of blood clots. Currently, no other oral anticoagulants are available in the U.S., though several are being studied. Coumadin has been available for over 50 years and remains a commonly used medication. However, several disadvantages are associated with its use, thus prompting the development of newer, improved agents. One of its main problems is the need for frequent blood monitoring so that the dose can be adjusted to strike a balance between clotting (too little medication) and bleeding (too much medication). Other problems with its use include a delayed onset, often necessitating the concurrent use of other, quicker acting anticoagulants until coumadin starts working and many interactions with other drugs, foods and herbal preparations. All anticoagulants are prescription drugs.
Injectable Anticoagulants
Injectable anticoagulants are an alternative to coumadin. Many can be given at home after learning the proper method of injection. They require less blood monitoring than coumadin but are more expensive. As for coumadin, bleeding is the main side effect. These agents include the low molecular weight heparins, dalteparin (Fragmin®), enoxaparin (Lovenox®), and tinzaparin (Innohep®), and a similar drug called fondaparinux (Arixtra®).
Oral Anticoagulants on the Horizon
Several oral anticoagulants are in late stages of clinical studies and may gain FDA approval soon. These drugs work slightly differently than coumadin, but produce the same effect and require little to no blood monitoring. Agents in this category include rivaroxaban, being studied by Bayer Pharmaceuticals, apixaban from Bristol-Myers-Squibb and Pfizer Pharmaceuticals, and dabigatran from Boehringer Ingelheim. According to Karissa Kim, Pharm.D. in an article published in "America's Pharmacist," drug interactions are possible with some of these new drugs, and bleeding remains a concern, as with any anticoagulant.
Antiplatelet Medications
Some medications prevent platelets within the blood from adhering to each other, thus improving blood flow for certain conditions. However, these drugs do not directly impact the clotting mechanism and must not be confused with or substituted for anticoagulants. Oral medications included in this category are aspirin, dipyridamole (Persantine®), clopidogrel (Plavix®), cilostazol (Pletal®) and ticlopidine (Ticlid®). These drugs should be used with coumadin only if directed by a physician because combination therapy may increase the risk of bleeding.
References
- "America's Pharmacist"; Oral, Direct Factor Xa Inhibitors and Thromboembolic Disorders; Karissa Kim, Bradley Hein, Patricia Wigle; February 2009
- "Pharmacotherapy: A Pathophysiologic Approach"; DiPiro JT, Talbert RL, Yee, GC, et al, editors; 2005. Chapter 19 "Venous Thromboembolism", Haines ST, Zeolla M, Witt DM.
- "AHFS Drug Information"; McEvoy GK, editor; 2009.
