Drug cabinet: Antiplatelets
Antiplatelet medications, such as aspirin and clopidogrel, are commonly used to reduce the risk of heart attack. Senior Cardiac Nurse Christopher Allen finds out more from Professor Albert Ferro.
What are antiplatelet drugs and why are they given?
Antiplatelet drugs are given to someone who has had a heart attack, to reduce the chances of them having another. You might also be given antiplatelets if you have had a stent fitted to a narrowed artery, if you’ve had a stroke or if you’ve been diagnosed with peripheral vascular disease. The most common antiplatelet drug used in preventing further heart attacks is aspirin. Other drugs include clopidogrel, prasugrel and ticagrelor.
Platelets are cells that circulate around your body in the bloodstream. They are responsible for blood clotting, which is normally a very useful function; for example, when you cut yourself it stops you from bleeding excessively. However, in coronary heart disease they can cause problems. A heart attack happens after fatty plaque builds up in the arteries that supply your heart. If this plaque ruptures, the body’s natural response is to clot around the rupture, so platelets are activated and form a blood clot. This blocks the artery and prevents blood from reaching a part of your heart muscle. Starved of oxygen, the cells in the heart muscle start to die, and in some cases this can lead to heart failure.
Antiplatelet drugs can reduce the chance of a heart attack because they prevent abnormal clotting in the arteries by telling platelets not to stick together and form a blood clot.
Antiplatelet drugs prevent abnormal clotting in the arteries
How long would I take them for?
Following a heart attack, you will most commonly be given aspirin for life, plus another antiplatelet drug to be taken for a year. This is especially important if you have had a stent fitted, as the chances of a blood clot forming inside the stent are much higher during the first year. Each drug works in a slightly different way to stop platelets forming blood clots, meaning that two can work effectively together. If you’re intolerant of aspirin, you may take one of the other antiplatelet drugs for life instead. Most commonly this would be clopidogrel, which works at least as well as aspirin at preventing blood clots. The reason aspirin is preferred as a first-line drug is because it’s been around for longer, so we have the most experience in its use.
Why am I taking aspirin and warfarin, don’t they do the same thing?
Aspirin and warfarin are sometimes prescribed together, and this is because they not only work differently, they also help manage different conditions. Aspirin is most commonly prescribed for those who have been diagnosed with coronary heart disease to help reduce their risk of having a heart attack, and acts on the platelets. Warfarin is an anticoagulant rather than an antiplatelet. It acts on a different part of the clotting process – it reduces the liver’s ability to use vitamin K to make blood clotting proteins – and is used in conditions such as atrial fibrillation (AF) and when you have a metal heart valve, to reduce the risk of having a stroke due to a blood clot forming. Taking aspirin will not reduce your risk of having a stroke if you have AF or a metal heart valve, and similarly, taking warfarin will not reduce your risk of having a heart attack.
If you’re taking antiplatelets you should avoid taking ibuprofen or other painkillers
Any issues with other drug interactions?
If you’re taking antiplatelets you should avoid taking ibuprofen or other painkillers in the same family, as they can increase your risk of bleeding if taken together.
The Medicines and Healthcare products Regulatory Agency says that taking the antiplatelet drug clopidogrel with omeprazole or esomeprazole (types of drugs that suppress stomach acid, known as PPIs) “is to be discouraged unless considered essential”, and that other PPIs should be considered instead. There is some evidence that omeprazole or esomeprazole may prevent clopidogrel from working as effectively, leading to more heart attacks among people who took both drugs. This evidence is limited, though. If you have concerns, speak to your doctor.
Why have I been told to stop taking my medication?
If you’re taking two antiplatelet drugs – usually because you’ve had a stent fitted - this will usually be for a year and after that you’ll be advised to stop one of the drugs. You will only need one antiplatelet drug for life, as the risk of a clot forming is much lower after the first year. The bulk of research suggests that it’s then safe to stop taking the second antiplatelet medication.
You may be more prone to nosebleeds, and bruising or bleeding for longer than usual
Are there any side effects?
Antiplatelets can irritate the lining of the stomach, so there is a risk of gastrointestinal side effects such as indigestion and stomach aches. It’s important to tell your GP about any side effects you’re having, but keep taking your medication in the meantime. You might also develop a gastric (stomach) ulcer and need to start taking proton pump inhibitors to protect the lining of your stomach.
Because antiplatelet drugs reduce the ability of the blood to clot, it means that you may be more prone to nosebleeds, and bruising or bleeding for longer than usual if you cut or injure yourself. This is normal, and on balance this is an side effect because of the significant reduction in your risk of having a heart attack.