Blood Thinners: Safety Tips and Precautions

Blood Thinners are important group of drugs required by many patients with heart related illnesses, which includes patients suffering from acute or past heart attacks, patients with angina of all varieties, brain strokes new or old. Patients with a history of valve surgery especially with metallic valves. Patients with irregular heartbeats especially a condition called atrial fibrillation and those with clot formation in leg veins and lungs. These come under the category of life saving drugs.

This group of medications need to be divided into 2 groups:

Anti platelet drugs

These are the agents which blunt the effects of blood cells called platelets. These are tiny, irregularly, shaped blood cells that play a vital role in our body’s ability to form blood clots, leading to stoppage of bleeding and initiating healing process after any bodily injury.

Examples of commonly used anti-platelet drugs are: aspirin, clopidogrel. Ticagrelor and prasugrel.

These agents are used either singly or in a combination of 2 to make them more effective. They are often to be taken on a long term usually life-long.

The most common indication for their use is acute coronary syndrome after a myocardial infarction, unstable angina, following angioplasty and stenting blocked coronary arteries, post- bypass surgery, after thrombotic strokes and transient ischemic attacks. In addition, in conditions like atrial fibrillation, after valve replacement, thrombosis or clotted leg veins (DVT) and clots in lung arteries (Pulmonary embolism).

Anti-coagulants

These are medications that prevent blood clot formation or do not allow the existing clots to become larger. Commonly, used anti-coagulants are: Warfarin, acenocoumarin, apixaban, dabigatran, rivaroxaban, edoxaban (not available in India).

Warfarin needs regular testing of blood periodically by doing Prothrombin time, expressed as a ratio called INR (International normalized ratio). The therapeutic value of INR in most instances is kept between 2 and 3 by adjusting the dosage. On the other agents in the list which are called Direct Oral Anti coagulants (DOACs) have fixed doses and mostly do not need monitoring of coagulation parameters. Except in conditions like metallic heart valve and clots within the heart DOAC’s have largely replaced warfarin.

Precautions including restrictions for patients on Anti-Platelet Drugs:

 These will help to minimize the risk of bleeding. They should be cautious when engaging in activities that may lead to injury or bleeding.

Patient should inform their doctor including the dentist before any surgical procedure about their medication. It may have to be stopped temporarily to obviate serious bleeding during the procedure. In case of any major trauma patient needs to take immediate medical help even if things look alright. Bleeding especially internal can start hours or a few day later also and produce alarming clinical features.

Pain killers like ibuprofen or naproxen can increase the bleeding risk and should be avoided as much as possible. Additional aspirin should not be taken by these patients. Paracetamol is the only safe drug for pain and fever relief in this situation and in moderate doses up to 1 to 2 grams in a day.

Good lifestyle with regular moderate exercise and de stressing methods like deep breathing and meditation should be encouraged. In addition, periodic blood tests like blood counts, kidney and liver function tests are recommended because their derangement can increase bleeding risks.

Precautions including restrictions in diet for patients on Anti Coagulants:

Warfarin or Acenocoumarin:

These are vitamin K antagonists and food items containing high amounts of Vit K should be careful. These are green leafy vegetables like collard greens (Haakh), spinach, mustard leaves (Sarson ), cauliflower, broccoli, green onions, spinach etc. Since these vegetables are a part of our diet and are recommended for good health, there is no absolute denial to consume them. Since their intake can reduce the potency of Warfarin, it is recommended these items to be taken in same amount daily and consistently so that dose remains adjusted. INR test which is always done once a month should be ensured to be in the therapeutic range of 2 to 3.

Foods which are very low in Vit K and are allowed in usual amounts are potatoes, turnips, cucumber, carrots, bell pepper (Shimla Mirch), peeled onions, mushrooms, one to two cloves of garlic, Corn, bamboo shoot etc. More than 3 to 4 cloves of garlic can potentiate the effects of Warfarin and cause bleeding. Likewise, poultry, meat, fish (except salmon or fatty fish), eggs, milk, cheese, bread, rice and cereals, tea and coffee are freely allowed.

Drug Interactions with Warfarin

There are a number of common medicines which can alter the action. Some of them are: amiodarone, Thyroxine, several antibiotics including rifampicin. Drugs for seizure control like phenytoin. It is always a good practice to inform the treating doctor prescribing additional drugs regarding your taking anticoagulant. In any case it is always desirable to get blood tested for INR to ensure that it is in therapeutic range. It should be remembered that all doctors may not be aware of these interactions.

Patients on DOAC’s (Apixaban, Dabigatran and Rivaroxaban)

A large number of patients who used to be on Warfarin are on these drugs these days. This is especially true for stroke prevention in atrial fibrillation, a very common arrhythmia after the age of 65 years of age.

General precautions are common to all blood thinners to minimize the reduction of bleeding already mentioned in the above columns. There are no dietary considerations like with Warfarin except to avoid Grapefruit. All vegetables and greens are permitted unrestricted.

Special Populations:

Renal and liver disease resulting in high serum creatinine levels and alterations in liver function should be looked for. Dose adjustment is needed otherwise bleeding risk can increase. Pregnant ladies and those feeding their babies are in general not given DOACs.

Antidotes/ Reversal Agents

Patients who are on these agents and get a major bleed prompt and complete  reversal is possible. Reversal agents are available. Idarucizumab (Praxbind) for dabigatran and Andexanet (Andexxa) for apixaban and rivaroxaban. In patients on DOAC’s who need urgent emergency surgery, these agents can be used just before the surgical procedure and have the procedure done without the risk of excessive bleeding. It is important to note that Vitamin K is an antidote for  warfarin but its doses etc are not so well worked out.

Blood thinners are commonly used life saving drugs in a variety of cardiovascular and blood clotting affected disorders. These can however be double edged swords and need to be used carefully and under medical supervision to have both adequate safety and efficacy. Patients need to be aware of the pros and cons and observe adequate precautions for an optimal effect of these agents.

The author is a Cardiologist and Founder Director Gauri Kaul Foundation