Pharmacology · Antiplatelet drugs
Ticagrelor !
An oral antiplatelet drug that blocks P2Y12 directly and reversibly, with no liver activation. Shortness of breath is a typical side effect.
Updated 2026-11-01
The figure shows the human P2Y12 receptor with AZD1283, an experimental P2Y12 blocker; no structure of the receptor with ticagrelor is available.
Mechanism of action
Ticagrelor is a cyclopentyltriazolopyrimidine, not a thienopyridine. It does not need to be activated: ticagrelor and its main metabolite, which are about equally potent, bind the P2Y12 receptor reversibly and stop ADP from activating the platelet. Because the binding is reversible, platelet function recovers as drug levels fall, without waiting for new platelets.
- Ticagrelor binds P2Y12 directly, with no activation step
- ADP signalling and platelet activation are blocked
- Binding is reversible: function returns as the drug is cleared
Pharmacokinetics
- Absorption
- Oral bioavailability about 36%; crushed tablets in water, by mouth or nasogastric tube, are equivalent to whole tablets.
- Distribution
- More than 99% bound to plasma proteins.
- Metabolism
- In the liver by CYP3A; its main metabolite is about as potent as ticagrelor.
- Elimination
- Mostly by hepatic metabolism, with recovery mainly in the faeces.
- Onset and duration
- Maximum platelet inhibition about 2 hours after a loading dose; it fades back to placebo levels by about 5 days after stopping.
Indications
- Acute coronary syndrome or past myocardial infarction, with low-dose aspirin, including after a stent. Myocardial Infarction (Heart Attack) →
- Coronary artery disease at high risk of a first heart attack or stroke. Stable angina →
- Mild acute ischaemic stroke or high-risk transient ischaemic attack. Transient ischaemic attack →
Adverse effects
Common
- Bleeding
- Shortness of breath (dyspnoea), usually mild and self-limiting
- Dizziness, nausea, diarrhoea
- Rise in uric acid
Contraindications
- History of intracranial haemorrhage
- Active pathological bleeding
- Hypersensitivity to ticagrelor
Key interactions
- Strong CYP3A inhibitors (ketoconazole, itraconazole, clarithromycin)
- Greatly raise ticagrelor levels, with more bleeding and dyspnoea; avoided.
- Strong CYP3A inducers (such as rifampicin)
- Greatly lower ticagrelor levels and its protection; avoided.
- Higher-dose aspirin
- In the main trial, results favoured ticagrelor only with low aspirin maintenance doses.
- Opioids
- Delay and reduce its absorption.
- Simvastatin, lovastatin and digoxin
- Their levels rise; digoxin levels are checked.
What is monitored
- Signs of bleeding
- Breathlessness, and heart rate or ECG if symptoms suggest slow rhythms
- Liver function; it is avoided in severe liver impairment
- Digoxin levels when combined
Administration and safety
- Oral, twice a day; crushed tablets can be given by mouth or nasogastric tube
- Given with low-dose aspirin only; other aspirin-containing products are avoided
- Not started before urgent coronary bypass surgery; usually paused for several days before major surgery, as planned by the team
- Platelet function tests for heparin-induced thrombocytopenia can be falsely negative while on it
Nursing care
- Ask about history of brain bleeding, slow heart rhythms and other medicines before the first dose
- Explain that mild shortness of breath is common and often settles; worsening or resting breathlessness is reported
- Watch for bleeding signs and for fainting or a slow pulse
- Teach the patient not to stop it without the cardiology team
Pregnancy and breastfeeding
Case reports have not shown a drug-related risk of birth defects, but human data are limited; breastfeeding is not recommended.
Test yourself
Think of the answer, then tap the question to see it.
Why does ticagrelor not depend on CYP2C19 genotype the way clopidogrel does?
It is not a prodrug: ticagrelor itself (and its active metabolite) blocks P2Y12, so no CYP2C19 activation step is needed.
Which typical side effect of ticagrelor is not seen with clopidogrel?
Shortness of breath (dyspnoea), usually mild, which often settles during treatment.
Which past event is a contraindication to ticagrelor?
A previous intracranial haemorrhage.
What kind of aspirin regimen accompanies ticagrelor?
Only low-dose aspirin: in the main trial, ticagrelor's benefit was seen with low aspirin maintenance doses.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - TICAGRELOR tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Ticagrelor: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); 4NTJ: Structure of the human P2Y12 receptor in complex with an antithrombotic drug (RCSB Protein Data Bank, 2014).
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Representative model, for educational purposes only.