Clopidogrel

Clopidogrel (brand name Plavix) is an antiplatelet medicine. This means it reduces the risk of blood clots forming.

How does clopidogrel work?

Normally, when there is a cut or break in a small blood vessel, a blood clot forms. This plugs the hole until the blood vessel heals.

Small cells in the blood called platelets cause the blood to clot. When a platelet detects a damaged area of a blood vessel, it produces a chemical. This attracts other platelets and makes them stick together to form a blood clot.

Clopidogrel reduces the ability of the platelets to stick together and reduces the risk of clots forming. This protects you from having a stroke or heart attack.

When is clopidogrel used?

You may be given clopidogrel if you have had:

• a heart attack
• acute coronary syndrome (minor heart attack or unstable angina)
• a stroke or transient ischaemic attack (TIA)
• a coronary stent (a device to open up a blocked artery to the heart)
• an open heart operation
• peripheral arterial disease
• a vascular operation

Clopidogrel and low-dose aspirin

Sometimes, you may be given both low-dose aspirin and clopidogrel. Taken together, they're very effective. However, there is a higher risk of bleeding, usually in the gut. This risk increases with age. The key question for your doctor is whether the benefits outweigh the extra risk.

This combination treatment is prescribed for a limited period of time, usually up to a maximum of 12 months. After this period, your specialist will usually advise you to stop 1 of the 2 antiplatelet medications.

Missed or extra doses of clopidogrel

If you forget to take your dose of clopidogrel, take that dose as soon as you remember. You should then continue to take your course of clopidogrel as normal.

However, if it's almost time for the next dose, skip the missed dose. You should then continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

If you have to take 2 doses closer together than normal, there is an increased risk of side effects.

The patient information leaflet that comes with your medicine should also give you advice about what to do.

Clopidogrel may not be suitable to take if you have certain health conditions or are taking other medications.

Who can and cannot take clopidogrel?

Clopidogrel should not be taken if you have:

• an active (bleeding) peptic ulcer
• recently had a brain haemorrhage
• haemophilia or any other bleeding disorder

This is unless you're advised by a specialist.

To make sure clopidogrel is suitable for you, you should also tell you're doctor if you:

• have liver problems
• have kidney problems
• are at risk of bleeding - for example, if you are at risk of peptic ulcers
• have had an allergic reaction to any medications before taking clopidogrel

Clopidogrel must not be given to anyone under 18 years old, unless under specialist advice. It's also not recommended if you're pregnant or breastfeeding.

Your doctor or dentist may advise you to stop taking clopidogrel for a short time before a procedure or dental treatment. You should only make changes or stop medication following advice from a health professional.

Using clopidogrel with caution

Clopidogrel should be taken with caution if you:

• have liver problems
• have kidney problems
• are at risk of bleeding - for example, if you are at risk of peptic ulcers

Tell your GP if you've had an allergic reaction to any medications before taking clopidogrel.

Some people are advised to stop taking clopidogrel 7 days before a planned operation or dental extraction (removal of a tooth). This should always be on the advice of your doctor or surgeon.

Interactions with other medicines

When 2 or more medicines are taken together, the effects of one of the medicines can alter the effects of the other. This is known as a drug-drug interaction.

There is an increased risk of bleeding when clopidogrel is taken with some other medications, including:

• aspirin
• non-steroidal anti-inflammatory painkillers (NSAIDs) – like diclofenac, ibuprofen and naproxen
• dipyridamole – another type of antiplatelet
• warfarin – anticoagulant medicine that prevents your blood from clotting
• newer types of antiplatelet medicines – like prasugrel and Ticagrelor
• newer antithrombotic medicines – like ticlopidine or GpIIb/IIIa inhibitors (abciximab, tirofiban and dabigatran)

Some medications may also prevent clopidogrel from working as well as it should. They may also interact in other ways.

Interactions with food and alcohol

There are no known interactions between clopidogrel and food. However, it's a good idea to take clopidogrel with or after food to help reduce irritation to the stomach.

It may be safe to drink alcohol with clopidogrel as long as you:

• check the patient information leaflet that comes with the medicine
• take the correct dose of your medicine
• do not drink more than the maximum recommended daily limits of alcohol

Taking more than the recommended dose of clopidogrel increases the risk of irritation to your stomach lining. This risk is increased if you drink more alcohol than the recommended daily limit. This may also lead to bleeding from the stomach.

Side effects of clopidogrel

Clopidogrel can cause side effects, although serious reactions are rare.

Common side effects of clopidogrel can include:

• headaches
• dizziness
• nausea
• diarrhoea
• constipation
• indigestion (dyspepsia)
• stomach ache or abdominal pain
• nosebleeds
• increased bleeding - for example, easy bruising or your blood taking longer to clot when you cut yourself

Speak to your GP if any of these side effects get worse or don't go away.

Clopidogrel is unlikely to affect your ability to drive. However, some people may feel dizzy when taking it. Avoid driving if you feel dizzy.

Allergic reaction

In some cases, clopidogrel can cause an allergic reaction.