Anticoagulant Medications
Anticoagulants are types of drugs that manipulate the blood coagulation process (the so-called plasmatic coagulation). They inhibit thrombus formation, meaning that they prevent blood clots from forming too easily.
Anticoagulants generally include non-VKA oral anticoagulants (NOACs), heparins and vitamin K antagonists. All of these have different ways of working. Due to the pharmacological mode of action, the use of anticoagulants may be associated with an increased risk of occult or overt bleeding from any tissue or organ which may results in post haemorrhagic anaemia.
The signs, symptoms and severity will vary according to the location (e.g. blood in urine, severe bruising) and degree or extent of the bleeding and/ or anaemia. Your doctor will work out which anticoagulant is right for you based on the indication and the presence of any other medical conditions.
All licensed anticoagulants deliver a positive benefit risk profile. Although all anticoagulants can increase the risk of bleeding, strategies are available to reduce or stop bleeding.
Vitamin K Antagonists (e.g. Warfarin, Coumarins)
Vitamin K Antagonists (VKA) like Warfarin are a group of substances that reduce blood clotting by reducing the action of vitamin K. Vitamin K in turn is needed for the proper synthesis of certain clottings factors in the liver.
VKA comes in a tablet form and is taken orally. If you take VKA, you will need a specific blood test that measures International Normalised Ratio, more commonly called INR. Your INR will be measured at an outpatient clinic.
If your INR is too high: Your dose of VKA may need to be reduced to lower your risk of excessive bleeding. Your doctor will determine the cause of the fluctuation and advise you if your medication or lifestyle habits may need to change. Your doctor will also tell you if your VKA dose needs to change.
If your INR is too low: Your dose of VKA may need to be increased to lower your risk of clotting. Your doctor will tell you if your dose of VKA needs to change.
You may also find the following advice helpful in maintaining the right dose for you:
- Diet: Try to keep your diet consistent. Sudden changes in your food intake might mean that your dose will need to be adjusted. Maintain your usual consumption of vitamin K containing vegetables (spinach, broccoli, romaine lettuce). As always, please check with your healthcare professional to monitor any changes that may occur.
- Alcohol: Avoid drinking more than the recommended amount (three to four units a day for men which is equivalent to one large glass of red/white wine; or two to three units a day for women which is equivalent to two small glasses of red/white wine). This is a suggestion and will differ from person to person, please check with your healthcare professional for recommendations that are suitable for you.
- Medications: Changes in medication can also alter the effectiveness of VKA. When one drug alters the effect of another, this is called a drug-drug interaction. Before you start or stop any medications you should check with your doctor or a healthcare professional. You should also try to take your VKA at the same time each day.
A normal resting heart rate is usually between 60 and 100 beats per minute but in AF this number can be significantly higher. If the number of beats per minute is significantly higher than 100, significantly lower than 60, or if you have an irregular heartbeat, you should seek medical attention.
Non-VKA Oral Anticoagulants (NOACs)
Rivaroxaban
Rivaroxaban is a direct Factor Xa inhibitor oral anticoagulant. Rivaroxaban works by inhibiting Factor Xa, a protein that helps blood clots form. Rivaroxaban comes in a tablet form. Rivaroxaban should be swallowed whole.
Edoxaban
Edoxaban is a direct Factor Xa inhibitor oral anticoagulant. Edoxaban works by inhibiting Factor Xa, a protein that helps blood clots to form. Edoxaban comes in a tablet form. Edoxaban should be swallowed whole, with or without food.
Apixaban
Apixaban is also a direct Factor Xa inhibitor oral anticoagulant. Apixaban works by inhibiting Factor Xa, a protein that helps blood clots form. Apixaban comes in a tablet form. Apixaban should be swallowed whole with or without food.
Dabigatran
By contrast to the NOACs listed above, Dabigatran is a direct thrombin inhibitor oral anticoagulant. Dabigatran works by inhibiting the action of thrombin, a protein that helps blood clots form. Dabigatran comes in capsule form. Dabigatran should be swallowed whole with or without food. The capsule should not be chewed or opened and the capsule should be kept in the original packaging.
NOACs and Alcohol:
Alcohol can interact with NOACs and influence bleeding. You should avoid heavy or binge drinking while taking a NOAC. Alcohol intake may have different effects on different patients, so please check with your healthcare professional what is appropriate for you.
Medications: Tell your doctor or pharmacist that you are taking a NOAC before you start any new medicines or complementary therapy.
Medical and dental procedures: – Tell your doctor or dentist that you are taking a NOAC well before any planned procedure, including operations in hospital, minor procedures at the doctor’s surgery and any dental procedures. Your NOAC therapy will be considered during the planning of your operation/procedure. Do not stop taking your NOAC unless instructed by your doctor.
Monitoring with NOACs:
Unlike vitamin K antagonists, NOACs show consistent, dose dependent plasma levels across a range of patient populations and therefore do not require routine coagulation monitoring. It is important, however, before you start NOAC therapy that your doctor checks your kidney function. When on NOAC therapy, your doctor might decide to monitor your kidney function regularly – especially if you are over 75 or have existing kidney problems. Your doctor will advise you about the frequency of the tests.
Heparin
Heparin works immediately, preventing further clotting and is available in two forms:
- Standard (unfractionated) heparin
- Low-molecular-weight heparin (LMWH)
Standard (unfractionated) heparin can be administered either through an intravenous or subcutaneous injection or an intravenous infusion/drip. The dose varies from person-to-person and careful monitoring by your doctor/nurse is required. This may involve a few days’ stay in hospital to ensure you receive the right dose.
LMWHs, which include dalteparin, enoxaparin, and tinzaparin, are usually given as subcutaneous injections. LMWHs work differently from standard heparin, so there is no need to stay in hospital for monitoring. As in all anticoagulants, the most common adverse event encountered is bleeding.
