P2Y12 inhibitors
Blocking the platelet ADP receptor P2Y12, so platelets clump less.
Also called P2Y12 receptor antagonists and ADP receptor antagonists.
Class card
- Drugs
- Clopidogrel, Ticagrelor and Prasugrel
- Used for
- Acute coronary syndromes, including stenting (PCI)
- Preventing heart attacks after a heart attack
- Lowering stroke risk after ischemic stroke or TIA
- Peripheral artery disease
- Known for
- Bleeding, sometimes fatal
- Name stems
- -grel-, -grel
4 cards: the class, and each drug in it.
Mechanism of action
How do P2Y12 inhibitors work?
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.
The drugs
P2Y12 inhibitors with a card
- ClopidogrelIts effect depends on activation by CYP2C19, so a person's genes and drugs such as omeprazole can weaken it.
- TicagrelorNot a prodrug and binds reversibly, so it works within hours without needing activation; breathlessness is its best-known side effect.
- PrasugrelIn PCI patients it prevented more heart attacks than clopidogrel (TRITON-TIMI 38) but caused more bleeding, including bleeding after bypass surgery.
Uses
What are P2Y12 inhibitors used for?
- Acute coronary syndromes, including stenting (PCI)
- Preventing heart attacks after a heart attack
- Lowering stroke risk after ischemic stroke or TIA
- Peripheral artery disease
Side effects
Side effects of P2Y12 inhibitors
- Bleeding, sometimes fatalKnown forSerious
- Gastrointestinal bleedingSerious
- Thrombotic thrombocytopenic purpura (TTP)Serious
- Breathlessness (ticagrelor)
- Slow heart rhythms and pauses (ticagrelor)Serious
- Raised uric acid (ticagrelor)
- Angioedema and other allergic reactionsSerious
- Rash
- Liver injury (clopidogrel, rarely)Serious
- Agranulocytosis and aplastic anemia (clopidogrel, rarely)Serious
What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.
Watch for
Cautions
- Before elective surgery they are stopped 5 days (clopidogrel, ticagrelor) or 7 days (prasugrel) ahead if an antiplatelet effect is not wanted.
- Stopping early, above all soon after a coronary stent, raises the risk of stent thrombosis, heart attack and death.
- Contraindicated with active pathological bleeding such as a bleeding peptic ulcer or intracranial hemorrhage.
- Aspirin, anticoagulants, NSAIDs, SSRIs and SNRIs all add to the bleeding risk.
Remember them
A way to remember them
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
Name stems
-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
Don't mix them up
Classes easily confused with these
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Clopidogrel tablets: label (DailyMed)
- Ticagrelor tablets: label (DailyMed)
- Prasugrel tablets: label (DailyMed)
- P2Y12 Inhibitor (NCI Thesaurus)
- Ticagrelor (NCI Thesaurus)
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
Practice P2Y12 inhibitors with the other classes in this group: what each drug is, how it works, what it treats and what it's known for.
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