Clopidogrel

Clopidogrel is a prescription medication used to prevent blood clots in people who have recently been hospitalized with chest pain, or for people who have recently had a heart attack or stroke. Clopidogrel belongs to a group of drugs called antiplatelets, which help prevent harmful blood clots from forming in the body.

This medication comes in tablet form and is taken once a day, with or without food.

Common side effects of clopidogrel include bleeding, headache, dizziness, and nausea.

Clopidogrel gets converted to its active form by an enzyme in the body known as CYP2C19. Drugs such as clopidogrel that require activation by the body are known as prodrugs. Some patients have a deficiency in CYP2C19. Patients with a deficiency in CYP2C19 are known as "poor metabolizers" or "intermediate metabolizers."

CYP2C19 testing is done to determine whether clopidogrel is likely to be an effective treatment. Many factors can affect levels of clopidogrel in the blood, such as drug interactions. Without testing, clopidogrel may not be an effective treatment. If you are a poor or intermediate metabolizer, your doctor may adjust your dose of clopidogrel.

Without being activated, clopidogrel is not able to stop blood clots from forming. In poor or intermediate metabolizers, clopidogrel may not get converted to its active form, and may not be effective at preventing blood clots. Being a poor or intermediate metabolizer is associated with a higher risk of heart attack or stroke in patients being treated with clopidogrel.

Clopidogrel is a prescription medication used to prevent blood clots in people who have recently been hospitalized with chest pains, or for people who have recently had a heart attack or stroke. It is also used in people with certain heart and blood vessel disorders.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Clopidogrel may be found in some form under the following brand names:

• Plavix

Clopidogrel can cause serious side effects including:

• See "Drug Precautions" section
• A blood clotting problem called Thrombotic Thrombocytopenic Purpura (TTP). TTP can happen with clopidogrel, sometimes after a short time (less than 2 weeks). TTP is a blood clotting problem where blood clots form in blood vessels; and can happen anywhere in the body. TTP needs to be treated in a hospital right away, because it may cause death. Get medical help right away if you have any of these symptoms and they can not be explained by another medical condition:
  • purplish spots (called purpura) on the skin or in the mouth (mucous membranes) due to bleeding under the skin
  • your skin or the whites of your eyes are yellow (jaundice)
  • you feel tired or weak
  • your skin looks very pale
  • fever
  • fast heart rate or feeling short of breath
  • headache
  • speech changes
  • confusion
  • coma
  • stroke
  • seizure
  • low amount of urine, or urine that is pink or has blood in it
  • stomach area (abdominal) pain
  • nausea, vomiting, or diarrhea
  • vision changes

Tell your doctor if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of clopidogrel. For more information, ask your doctor or pharmacist.

Tell your doctor about all the medicines you take, including prescription, non-prescription medicines, vitamins and herbal supplements.

Clopidogrel may affect the way other medicines work, and other medicines may affect how clopidogrel works. 

Taking clopidogrel with certain other medicines may increase your risk of bleeding. Especially tell your doctor if you take:

• aspirin, especially if you have had a stroke. Always talk to your doctor about whether you should take aspirin along with clopidogrel to treat your condition.
• Non-steroidal anti-inflammatory drugs (NSAIDs). Ask your doctor or pharmacist for a list of NSAID medicines if you are not sure.
• warfarin (Coumadin, Jantoven)

Know the medicines you take. Keep a list of them to show your doctor or pharmacist when you get a new medicine.

Clopidogrel may not work as well in people who:

• have certain genetic factors that affect how the body breaks down clopidogrel. Your doctor may do genetic tests to make sure clopidogrel is right for you.
• take certain medicines, especially omeprazole (Prilosec) or esomeprazole (Nexium). Your doctor may change the medicine you take for stomach acid problems while you take clopidogrel.

Clopidogrel can cause bleeding which can be serious and can sometimes lead to death. Clopidogrel is a blood thinner medicine that lowers the chance of blood clots forming in your body. While you take clopidogrel:

• you may bruise and bleed more easily
• you are more likely to have nose bleeds
• it will take longer for any bleeding to stop

Call your doctor right away if you have any of these signs or symptoms of bleeding:

• unexpected bleeding or bleeding that lasts a long time
• blood in your urine (pink, red or brown urine)
• red or black stools (looks like tar)
• bruises that happen without a known cause or get larger
• cough up blood or blood clots
• vomit blood or your vomit looks like coffee grounds

Do not stop taking clopidogrel without talking to the doctor who prescribes it for you. People who are treated with a stent, and stop taking clopidogrel too soon, have a higher risk of getting a blood clot on the stent, having a heart attack, or dying. If you must stop clopidogrel because of bleeding, your risk of a heart attack may be higher.

Do not take clopidogrel if you:

• currently have a condition that causes bleeding, such as a stomach ulcer
• are allergic to clopidogrel or other ingredients in clopidogrel tablets.

Grapefruit and grapefruit juice may interact with clopidogrel and lead to potentially dangerous effects. Discuss the use of grapefruit products with your doctor.

Before you take clopidogrel, tell your doctor if you:

• have a history of bowel (gastrointestinal) or stomach ulcers
• have a history of bleeding problems
• plan to have surgery or a dental procedure. 
• are pregnant or plan to become pregnant. 
• are breastfeeding or plan to breastfeed. 

Tell all of your doctors and your dentist that you are taking clopidogrel. They should talk to the doctor who prescribed clopidogrel for you before you have any surgery or invasive procedure.

Tell your doctor about all the medicines you take, including prescription, non-prescription medicines, vitamins and herbal supplements.

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if clopidogrel will harm your unborn baby.

Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if clopidogrel passes into your breast milk. You and your doctor should decide if you will take clopidogrel or breastfeed. You should not do both without talking to your doctor.

• Take clopidogrel exactly as your doctor tells you.
• Do not change your dose or stop taking clopidogrel without talking to your doctor first. Stopping clopidogrel may increase your risk of heart attack or stroke.
• Take clopidogrel with aspirin as instructed by your doctor.
• You can take clopidogrel with or without food.
• If you miss a dose, take clopidogrel as soon as you remember. If it is almost time for your next dose, skip the missed dose. Take the next dose at your regular time. Do not take 2 doses of clopidogrel at the same time unless your doctor tells you to.
• If you take too much clopidogrel, call your doctor or go to the nearest emergency room right away.
• Talk with your doctor about stopping your clopidogrel before you have surgery. Your doctor may tell you to stop taking clopidogrel at least 5 days before you have surgery to avoid excessive bleeding during surgery.

The recommended daily dose of clopidogrel is 75 mg once daily orally, with or without food.

If you take too much clopidogrel call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If clopidogrel is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

• Store clopidogrel at 59°F to 86°F (15°C to 30°C).

Keep clopidogrel and all medicines out of the reach of children.

WARNING: DIMINISHED EFFECTIVENESS IN POOR METABOLIZERS  

The effectiveness of clopidogrel is dependent on its activation to an active metabolite by the cytochrome P450 (CYP) system, principally CYP2C19. Clopidogrel at recommended doses forms less of that metabolite and has a smaller effect on platelet function in patients who are CYP2C19 poor metabolizers. Poor metabolizers with acute coronary syndrome or undergoing percutaneous coronary intervention treated with clopidogrel at recommended doses exhibit higher cardiovascular event rates than do patients with normal CYP2C19 function. Tests are available to identify a patient's CYP2C19 genotype; these tests can be used as an aid in determining therapeutic strategy. Consider alternative treatment or treatment strategies in patients identified as CYP2C19 poor metabolizers.