Anticoagulant Medications As our population ages, patients are living longer as a result of advances in medical technology, surgical procedures, and drug development(Bressler MD & Bahl PhD, 2003). The average older person is taking two to five prescription medications daily and one in five of this age group has a medication related hospitalization annually (McLean & LeCouteur, 2004).
In my eighteen years of nursing, I have taken care of many patients being treated with anticoagulant medications for various reasons, and I have found that most of these patients are not educated about the risks, benefits, and adverse reactions associated with anticoagulants. In this paper, I will focus on Warfarin (Coumadin) the most commonly prescribed anticoagulant. I will discuss the mechanism of Warfarin in the body, therapeutic uses, monitoring treatment, and adverse reactions. I will also explain the therapeutic effects, risks, and benefits of taking Warfarin in a patient that has a mechanical heart valve.
“Anticoagulants are drugs that reduce formation of fibrin”(Lehne, 2010, p. 597). The first anticoagulant used to prevent clotting during open-heart surgery in individuals with disseminated intravascular coagulation (DIC) was heparin (Kee & Hayes, 2003). Heparin works by binding with antithrombin III causing inactivation of thrombin. When thrombin is inactivated, the conversion of fibrin to fibrinogen does not take place, preventing clot formation (Kee & Hayes, 2003). Low-molecular-weight heparins (LMWH) are the most commonly used heparin therapy.
They are derivatives of the standard heparin, but they have a lower risk for bleeding (Kee & Hayes, 2003). There are five low-molecular-weight heparins namely enoxaparin sodium, dalteparin sodium, ardeparin, danaparoid, and tinzaparin sodium (Kee & Hayes, 2003). Oral anticoagulants are also widely used today. Examples of these are warfarin, dicumarol, and anisindione (Kee & Hayes, 2003). Mechanism Warfarin suppresses coagulation by decreasing production of four clotting factors, namely, factors VII, IX, X, and prothrombin (Lehne, 2010).
These factors are called vitamin K-dependent clotting factors, because an active form of vitamin K is needed to produce them. Warfarin inhibits the enzyme needed to convert vitamin K to the active form. Because of this action, Warfarin is referred to as a vitamin K antagonist (Lehne, 2010). “In therapeutic doses, warfarin reduces production of vitamin K-dependent clotting factors by 30% to 50%. ”(Lehne, 2010, p. 604). Warfarin doses taken by mouth, are readily absorbed into the bloodstream where it binds to albumin. Noticeable anticoagulant effects are delayed even though warfarin acts quickly to inhibit clotting factor production.
(Lehne, 2010). Because the delayed effects, warfarin is not used in emergent treatment. When rapid action is indicated for treatment, anticoagulant therapy can be initiated with heparin (Lehne, 2010). Adverse Reactions Bleeding or hemorrhage is the major adverse effect of warfarin and individuals taking this medication should be closely monitored for signs of bleeding (Kee & Hayes, 2003). These include petechiae, ecchymosis, and hematemesis among many others. Due to the oral anticoagulants being highly protein – bound, drug-to-drug interactions are also common.
The patient should know and discuss other drugs that he or she is taking with any physician rendering treatment. Aspirin, non-steroidal anti-inflammatory drugs, sulfonamides, allopurinol, phenytoin, and oral hypoglycemic agents for diabetes can cause interactions with warfarin and can enhance bleeding (Kee & Hayes, 2003). Acetaminophen should be used as a substitute for aspirin when taking warfarin (Kee & Hayes, 2003). In addition, there are antidotes in case warfarin or heparin has been taken in toxic amounts. Vitamin K or phytonadione is given as the antidote for warfarin overdose and protamine sulfate for heparin (Kee & Hayes, 2003).
There are also special considerations in the individual’s diet when taking anticoagulants. Vitamin K can be found in our daily food intake and can disturb the drug’s action. Patients must be aware of their food intake,which foods are high in vitamin K and should consume them in small amounts. (Parks, 2009)
Foods that contain large amounts of vitamin K include cooked green leafy vegetables (spinach, collard greens, kale, turnip greens, broccoli, raw parsley, and green tea). (Parks, 2009) Other green leafy vegetables contain a smaller amount of vitamin K (green leaf lettuce, endive, brussel sprouts, cauliflower, and asparagus) and may be eaten regularly (Parks, 2009).
Eating foods with vitamin K in moderation is necessary to avoid reducing the effect of warfarin, causing potential clotting. (Parks, 2009). On the other hand, eating lesser amounts of vitamin K than normal will only enhance the effect of warfarin and can increase the risk of bleeding (Parks, 2009). Disease Synopsis In a patient with valvular disease, a mechanical heart valve (MHV) is intended to replace the diseased heart valve with its prosthetic equivalent.
There are two basic types of valves that can be used for valve replacement, mechanical or tissue valves. (“Wiki,” n. d. ) Mechanical heart valves are very reliable and allow the patient to live a normal life. Most mechanical valves last for 20 to 30 years. One of the major drawbacks of mechanical heart valves is patients with these implants require consistent life long anti-coagulation therapy. (“Wiki,” n. d. ) Clots formed by red blood cell and platelet damage can block up blood vessels and lead to very serious complications. (“Wiki,” n. d. ).
All MHV models are vulnerable to thrombus formation due to high shear stress, stagnation, and flow separation. Mechanical heart valves can also cause hemolytic anemia with hemolysis of the red blood cells as they pass through the valve. (“Wiki,” n. d. ) Therapeutic Uses Warfarin is used most often for long-term prophylaxis of thrombosis. “Specific indications are (1) prevention of venous thrombosis and associated pulmonary embolism, (2) prevention of thromboembolism in patients with prosthetic heart valves, and (3) prevention of thrombosis during atrial fibrillation.
”(Lehne, 2010, p. 605). Warfarin is the oral anticoagulant of choice for these indications. The drug has also been used to reduce the risk of recurrent transient ischemic attacks (TIA) and recurrent myocardial infarction (MI). (Lehne, 2010). Medication Name University of Wisconsin biochemistry professor Karl Paul Link and his co-workers first isolated dicoumarin, a molecule in spoiled sweet clover that causes cattle to hemorrhage and die. The discovery led to the development of Dicumarol, the first anticoagulant drug that could be taken orally. (MedicineNet, n. d. ).
Dicoumarol was a product of the plant molecule coumarin and the successor to Dicumarol was Warfarin(MedicineNet, n. d. ). Warfarin is named after WARF, the Wisconsin Alumni Research Foundation, to which Professor Link assigned the patent (MedicineNet, n. d. ). Both names, generic and trade, have a direct link to the medication. Monitoring Treatment Prothrombin time (PT) is a serum coagulation test that measures alterations in vitamin K-dependent factors. Treatment with warfarin prolongs PT ratio. Because the PT ratio can vary greatly among laboratories, results are reported in the form of an INR(Lehne, 2010).
The effectiveness of warfarin treatment is measured by an INR falling in a recommended range. Most patients have a target INR range between 2 and 3. If the INR is low, the warfarin dosage would need to be increased. The dose would be held for a period of time if the INR resulted in the high range(Lehne, 2010) When warfarin therapy is inititated, the INR must be checked daily for the first 5 days, twice a week for 1 to 2 weeks, once a week for the next 1 to 2 months, and every 2 to 4 weeks for the duration of therapy(Lehne, 2010).
These anticoagulant medications have very specific instructions by the prescribing physician and should be followed precisely because of the drug’s serious side effects. Safety concerns The individual being prescribed anticoagulants should discuss any past or present medical treatments with the prescribing physician to avoid interactions or complications. In addition, they should also let their prescribing physician know if they are seeing another doctor or even a dentist (MedicineNet, n. d. ).
The following conditions can affect the anticoagulant regimen and the prescribing physician should be made aware if these are present. These include fever that is present for more than a day, diarrhea, pregnancy or recent childbirth, menstrual bleeding that is unusual or is heavily bleeding(MedicineNet, n. d. ). Anticoagulants, just like any other medication, disrupt the normal processes inside the body therefore, it is very important to stick to the regimen given by the physicians to avoid unwanted side effects and interactions (MedicineNet, n. d. ). References.
Bressler MD, R. , & Bahl PhD, J. J. (2003). Principles of Drug Therapy for the Elderly Patient . Mayo Clinic Proceedings, 78, 1564-1577. Retrieved from www. mayoclinic. com Kee, J. , & Hayes, E. (2003). . In Pharmacology: A Nursing Process Approach (5th ed. , ). Philadelphia, PA: Elsevier Science Ltd. Lehne, R. A. (2010). . In Pharmacology for Nursing Care (7th ed ). St. Louis, Missouri: Saunders Elsevier. McLean, A. J. , & Le Couteur, D. G. (2004). Aging Biology and Geriatric Clinical Pharmacology Pharmalogical Reviews, 56(2), 163-184. http://pharmrev. aspetjournals.
org/content/56/2/163. full MedicineNet. (n. d. ). http://www. medterms. com/script/main/art. asp? articlekey=11826 Mosby’s Dictionary of Medicine, Nursing, & Health Professionals. (2009). In Anticoagulant (8th ed. ). St. Louis, Missouri: Mosby Elsevier. Parks, R. (2009). Anticoagulants: Vitamin K and your diet. Retrieved from http://www. webmd. com/a-to-z-guides/eating-a-steady-amount-of-vitamin-k-when-you-take-warfarin-coumadin Wikipedia. (n. d. ). In Mechanical Heart Valves. Retrieved November 26, 2011, from http://en. wikipedia. org/wiki/Artificial_valve#Mechanical_valves.