Clopidogrel

What is clopidogrel?

Clopidogrel is a medicine doctors prescribe to reduce a person’s risk of having a stroke, blood clot, or other heart-related event or condition after having an episode of severe chest pain, a heart attack, or a stroke.

Clopidogrel is the generic name of the brand name drug Plavix. It belongs to the drug class known as antiplatelet agents (or platelet inhibitors), and it works by preventing platelets from clumping and forming blood clots, enabling blood to flow and circulate smoothly.¹

What is clopidogrel used to treat?

The US Food and Drug Administration (FDA) has approved clopidogrel for the prevention of heart attack and stroke in patients who’ve been diagnosed with or recently had one of the following:²

• Heart attack (ST-elevation myocardial infarction or STEMI)

• Stroke

• Peripheral arterial disease

Clopidogrel is also indicated for preventing or reducing the incidence of heart attack and stroke in patients currently experiencing severe cardiac chest pain or unstable angina (acute coronary syndrome).

In addition, people who have undergone the following procedures may also benefit from taking clopidogrel off-label:¹

• Angioplasty

• Coronary stent placement

• Coronary artery bypass grafting

How do you take clopidogrel?

Clopidogrel is available in tablet form, in strengths of 75mg and 300mg.

Your doctor will decide which dose is best for you based on your condition. The most common dosages are outlined below.

For unstable angina and STEMI:³

• An initial loading dose of 300mg once

• A maintenance dose of 75mg, taken daily

• The duration of the treatment depends on how the person’s body responds to the medication

• Must be taken with aspirin

For a recent ischemic stroke, myocardial infarction, or peripheral arterial disease:³

• 75mg, taken daily

You must take clopidogrel precisely as prescribed by your doctor, even if your prescribed dose falls outside the typical range.

Seeing results

Because clopidogrel is prescribed as a preventative treatment, you may not feel anything when you take it, but that doesn’t mean it isn’t working. The onset of absorption within the body is two hours.³

In a study assessing the effectiveness of loading dose timing on platelet activity, one team of researchers found that patients who received a loading dose 4–8 hours before the intervention had significantly lower platelet reactivity than those who received it just before the procedure.⁴

Warnings and potential side effects of clopidogrel

Clopidogrel has a US FDA boxed warning. The drug relies on the CYP2C19 enzyme for its antiplatelet action. Some people have a genetic variation in CYP2C19 that can affect the metabolism of clopidogrel. If there’s reason to suspect you have the genetic variation, your doctor may test for it and will prescribe a different antiplatelet agent, if necessary.²

Similarly, drugs designed to inhibit CYP2C19 can affect how well clopidogrel is used in the body. If you’re taking a medication that inhibits CYP2C19, your doctor may prescribe an alternative to clopidogrel.

The most common side effects associated with clopidogrel include the following:³

• Chest pain

• Upper respiratory tract infection

• Urinary tract infections

• Headaches

• Runny nose

• Flu-like symptoms

• Joint stiffness

• Dizziness

• Diarrhea

• Skin rashes

• Depression

Rare side effects of clopidogrel (some of which are more severe) include the following:

• Low blood pressure

• Hepatitis

• Pancreatitis

• Aplastic anemia (low numbers of all blood cell types)

• Acute liver failure

• Muscle aches

• Eczema

• Erythema (skin redness)

• Agranulocytosis (severely low number of white blood cells)

• Severe neutropenia (reduced neutrophils, a type of white blood cell)

• Major bleeding events, indicated by black or red stool, vomiting blood that looks like coffee grounds, severe bruising, severe nose bleeds, bleeding gums, or very heavy periods

• Thrombotic thrombocytopenic purpura, signaled by bleeding, bruising, dizziness, fatigue, and difficulty breathing

Mild side effects typically resolve on their own. If your side effects are severe or persistent, call your doctor or 911.

Who should not take clopidogrel?

Clopidogrel is not appropriate for everyone. Specifically, the drug is contraindicated in the following groups:²

People with active pathological bleeding

Clopidogrel prevents clotting and is not suitable for people with active bleeding from conditions such as a hemorrhage in the brain or a peptic ulcer. 

People with hypersensitivity

Clopidogrel is not appropriate for people with an allergy (including a previous allergic reaction) to any of the drug’s active or inactive ingredients.

Long-term use of clopidogrel

Depending on the condition, doctors may prescribe clopidogrel for a few weeks to several months. However, some people need to take clopidogrel for longer, especially those who have undergone a heart procedure. In some cases, clopidogrel is taken for a lifetime.

Clopidogrel is often used long-term, particularly for patients at high risk for heart attack, blood clots, and stroke, and it works well as a maintenance drug. It is typically taken together with aspirin after cardiac stent placement, although this depends on the patient’s risk factors for bleeding and other health conditions.

Your doctor will weigh your risks and the drug’s potential benefits to determine how long you should take clopidogrel.

Missed doses

If you miss a dose of clopidogrel, take it as soon as you remember unless it’s nearly time for your next dose. If that’s the case, skip the missed dose and resume your regular dosing schedule.

Don’t take a double dose to make up for a missed one. If you struggle with remembering your medications, set a timer or reminder to help you.

Overdoses

Overdose symptoms may vary from person to person. One serious sign of an overdose is excessive bleeding, which could occur anywhere in the body. Other signs include vomiting, difficulty breathing, and extreme weakness. If you experience bleeding or any other signs of an overdose while taking clopidogrel, seek emergency medical care.²

What to discuss with your doctor before you start taking clopidogrel

Clopidogrel is generally well-tolerated and safe, but there are some things you’ll need to discuss with your doctor before starting the medication. Tell your doctor if you:¹

• Are taking other drugs, prescribed or over the counter, regularly or even occasionally 

• Take any supplements or vitamins

• Have any medical conditions, particularly liver or kidney disease

• Have a bleeding disorder (hemophilia or von Willebrand disease) 

• Have a history of bleeding (GI tract, eye, or brain)

• Have gastrointestinal problems, including stomach ulcers

• Have allergies to medications

• Are pregnant or planning to become pregnant

• Are breastfeeding

• Recently experienced a serious traumatic injury

• Have recently had (or plan to have) surgery or any medical procedures, including dental surgery

Ask your doctor if you should avoid certain foods while taking clopidogrel. If you drink alcohol, ask your doctor how much is safe.

Stopping clopidogrel

Don’t stop taking clopidogrel without consulting your doctor. Suddenly stopping the drug may increase your risk of having a heart attack, blood clot, or stroke.¹

It may need to be temporarily discontinued if you have a bleeding problem or a few days before and after any surgical procedure. In those cases, your doctor will let you know when to restart your medication.

Clopidogrel in pregnancy and breastfeeding

Clopidogrel is a pregnancy category B drug, according to the US FDA. Although studies on animals show no harm, there have been no adequate human studies indicating the drug is safe during pregnancy. You must speak with your doctor to determine the risks and benefits of taking clopidogrel while pregnant, as it can trigger excessive bleeding during delivery. Depending on the medical condition you are being treated for, your doctor may advise you to stop taking the drug before your due date.²

If you become pregnant while taking clopidogrel, schedule an appointment with your doctor to discuss how or if you’ll continue to take the medication throughout your pregnancy.

Animal studies show that clopidogrel may pass through breast milk; however, there are no studies proving this is the case in humans. Speak with your doctor well ahead of your due date to lay out your treatment plan.

Interactions with other drugs

Clopidogrel is known to interact with certain drugs, including the following:²

• Opioids, which may affect the body’s absorption of clopidogrel

• Non-steroidal anti-inflammatories (NSAIDs), which increase the risk of intestinal bleeding

• Warfarin, which increases the likelihood of abnormal bleeding

• Antidepressants, which increase the risk of bleeding

• Repaglinide, as clopidogrel can boost its side effects

• CYP2C19 inducers, which increase the body’s uptake of clopidogrel⁵

• CYP2C19 inhibitors, which decrease the body’s uptake of clopidogrel⁶

• St. John’s wort, which may increase clopidogrel concentrations in the blood, increasing the risk of bleeding

Allergy information

It’s not common, but some people may be allergic to clopidogrel or its components. A few of the common side effects, including certain skin rashes and itching, may be mild and are no cause for concern. However, if you experience severe allergy symptoms, you’ll need to seek urgent medical care. Signs of a severe allergic reaction may include any of the following:

• Severe skin rash all over the body that peels

• Swelling in the eyelids, mouth, tongue, throat, hands, or feet

• Difficulty breathing

• Vomiting

• Loss of consciousness

Drug approval history

• 1997: The US FDA approves clopidogrel under the brand name Plavix²

• 2012: The US FDA approves several generic versions of the drug⁷

Tips and advice for taking clopidogrel

Here is some advice for taking clopidogrel:

• You can take clopidogrel with or without food

• Never chew, split, or crush the tablet

• Take it with a full glass of water

• Don’t combine clopidogrel with aspirin unless your doctor advises it

• Take clopidogrel around the same time every day

• Do not eat grapefruit or drink grapefruit juice while taking this medication, as it can increase the risk of severe side effects

• Take care to prevent injuries and bleeding; avoid contact sports

• Be aware of and watch out for the signs of bleeding, including hemorrhagic stroke and gastrointestinal bleeding

• Check all of your medication labels to see if they contain NSAIDs, such as ibuprofen, aspirin, and naproxen (many over-the-counter medicines for cold symptoms or pain relief include these) because they could increase your risk of bleeding while taking clopidogrel

• Do not start on a course of steroids without letting your doctor know you are taking clopidogrel

• This medication is not suitable for people under 18 as its safety has not been established in this age group

• Keep your medication in a closed container at room temperature and away from direct heat and light

• Well before any surgical procedure, tell your doctor you are taking clopidogrel; you may be instructed to stop it at least five days beforehand

• Do not stop taking the medication or change your dose without guidance from your prescriber