Clopidogrel
An oral thienopyridine P2Y12 inhibitor used in acute coronary syndromes and after a heart attack, stroke or peripheral artery disease.
Drug card
- Class
- P2Y12 inhibitor
- How it works
- Blocking the platelet ADP receptor P2Y12, so platelets clump less
- Used for
- Acute coronary syndromes (unstable angina, NSTEMI, STEMI)
- Preventing heart attacks after a recent heart attack
- Preventing stroke after a recent ischemic stroke
- Established peripheral artery disease
- Known for
- Bleeding, sometimes life-threatening
- Its name
- -grel-, -grel means an antiplatelet drug (mostly P2Y12 blocker)
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does clopidogrel work?
A thienopyridine prodrug. CYP450 enzymes, chiefly CYP2C19, make an active metabolite that binds the platelet P2Y12 ADP receptor irreversibly, so ADP cannot activate glycoprotein IIb/IIIa and the platelet aggregates less for the rest of its 7 to 10 day life. People who are CYP2C19 poor metabolizers form less of the active drug.
Like other P2Y12 inhibitors: They block P2Y12, the platelet receptor for ADP. ADP then cannot switch on the glycoprotein IIb/IIIa complex, so fibrinogen does not bridge platelets together and aggregation falls. Clopidogrel and prasugrel are prodrugs whose active metabolites bind irreversibly, for the platelet's 7 to 10 day life; ticagrelor is active itself and binds reversibly, at a site apart from where ADP binds.
Uses
What is clopidogrel used for?
- Acute coronary syndromes (unstable angina, NSTEMI, STEMI)
- Preventing heart attacks after a recent heart attack
- Preventing stroke after a recent ischemic stroke
- Established peripheral artery disease
Side effects
Side effects of clopidogrel
- Bleeding, sometimes life-threateningKnown forSerious
- Gastrointestinal bleedingSerious
- Thrombotic thrombocytopenic purpura (TTP)Serious
- Itching
- Rash
- Stevens-Johnson syndrome, TEN and DRESSSerious
- AngioedemaSerious
- Agranulocytosis and aplastic anemiaSerious
- Hepatitis and acute liver failureSerious
- Diarrhea
- Taste disorders
- Headache
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Boxed warning: CYP2C19 poor metabolizers form less active metabolite and have more cardiovascular events, so another treatment is considered.
- Avoid omeprazole and esomeprazole, which cut its antiplatelet effect; pantoprazole and lansoprazole affect it less.
- Stop it 5 days before elective surgery if an antiplatelet effect is not wanted; stopping early otherwise raises cardiac risk.
- Aspirin, warfarin, NSAIDs, SSRIs and SNRIs add to the bleeding risk.
Good to know: Its effect depends on activation by CYP2C19, so a person's genes and drugs such as omeprazole can weaken it.
Remember it
A way to remember it
Ticagrelor ticks on and off; clopidogrel and prasugrel lock on for life.
Ticagrelor binds P2Y12 reversibly. The active metabolites of clopidogrel and prasugrel bind it irreversibly, so their effect lasts the platelet's 7 to 10 day lifetime, which is why they are stopped days before surgery.
Written for biofideX
Its name
-grel-, -grel means antiplatelet drug (mostly P2Y12 blocker)
Clopidogrel, prasugrel and ticagrelor block the platelet P2Y12 (ADP) receptor. The stem may end the name or sit inside it, as in ticagrelor and cangrelor.
- Every drug name stem
Its class
P2Y12 inhibitors
Other P2Y12 inhibitors with a card:
Easily mixed up with non-steroidal anti-inflammatory drugs and direct factor Xa inhibitors.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Blood clots and cholesterol
Clopidogrel is one of 19 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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