# Antiplatelet Drugs in Cardiology

> Antiplatelet drugs in cardiology for NEET-PG Medicine covering aspirin, P2Y12 inhibitors and GP IIb/IIIa antagonists, with choice and bleeding risk.

- Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/antiplatelet-drugs-in-cardiology
- Exam / course: NEET-PG · Subject: Medicine
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-08
- Last updated: 2026-10-08
- Reference basis: Harrison's Principles of Internal Medicine; ESC Guidelines on acute coronary syndromes; Katzung's Basic and Clinical Pharmacology
- How to cite: "Antiplatelet Drugs in Cardiology", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/antiplatelet-drugs-in-cardiology

## Direct answer

Antiplatelet drugs in cardiology prevent platelet aggregation on ruptured atherosclerotic plaque. Aspirin irreversibly inhibits COX-1 and so blocks thromboxane A2, P2Y12 inhibitors such as clopidogrel, prasugrel and ticagrelor block ADP-mediated activation, and glycoprotein IIb/IIIa antagonists block final fibrinogen binding during percutaneous coronary intervention. Aspirin is the foundation of coronary therapy, and the choice of P2Y12 agent depends on the clinical scenario and the balance between ischaemic and bleeding risk.

## What you must remember

- **Aspirin:** irreversible COX-1 acetylation; 75 to 150 mg daily long term, with a loading dose of 150 to 300 mg in acute coronary syndrome.
- **Clopidogrel:** a prodrug activated by CYP2C19, so poor metabolisers respond poorly; omeprazole and esomeprazole impair its activation, and pantoprazole is the preferred protectant.
- **Prasugrel:** a more potent irreversible P2Y12 inhibitor, contraindicated after prior stroke or transient ischaemic attack, not generally advised at age 75 or older, and given at a reduced dose below 60 kg.
- **Ticagrelor:** a reversible agent with faster onset that causes dyspnoea; the maintenance aspirin dose must be 100 mg or less.
- **GP IIb/IIIa antagonists:** abciximab, eptifibatide and tirofiban are given intravenously during PCI in selected high-thrombus-burden cases, with major bleeding and thrombocytopenia as the main risks.
- **Dual antiplatelet therapy:** aspirin plus a P2Y12 inhibitor, usually for twelve months after acute coronary syndrome, shortened in high bleeding risk according to current guidance.

## A 66-year-old man with an inferior STEMI

A 66-year-old man presents with an inferior ST elevation infarction and is taken for primary PCI. The regimen follows a sequence, from the first dose to the follow-up review.

1. **Give the aspirin load:** Aspirin 150 to 300 mg is given before primary PCI.
2. **Choose the P2Y12 agent:** Ticagrelor or prasugrel is preferred over clopidogrel in acute coronary syndrome, because they produce faster and more consistent platelet inhibition and lower the risk of stent thrombosis. The loading dose is given at the time of the procedure.
3. **Limit maintenance aspirin:** When ticagrelor is used, maintenance aspirin is kept at 100 mg or less.
4. **Adjust for anticoagulation:** If the patient later needs warfarin for atrial fibrillation, a direct oral anticoagulant is generally preferred, and triple therapy is kept only briefly (aspirin dropped early) before an anticoagulant with clopidogrel alone.
5. **Add gastric protection:** A proton pump inhibitor is co-prescribed during dual therapy to reduce gastrointestinal bleeding, and the stent and bleeding risks are reviewed at each follow-up.
6. **Record the bleeding baseline:** Bleeding history, renal function and haemoglobin are recorded before the regimen is finalised, because they shape how long dual therapy can safely continue.

Clopidogrel remains the reasonable choice for stable chronic coronary syndrome and elective PCI, and it is also the cost-conscious option.

## Where the examiner tests the timing

Stopping rules and drug interactions are the favourite timing traps.

- **Trap:** assuming all antiplatelets are stopped together before surgery. — **Correct:** aspirin is irreversible, so platelet function recovers only as new platelets are produced; clopidogrel is usually stopped about five days before elective surgery, while aspirin for coronary disease is generally continued.
- **Trap:** keeping a higher maintenance aspirin dose with ticagrelor. — **Correct:** a higher aspirin dose blunts the antiplatelet effect of ticagrelor, so the dose stays at 100 mg or less.
- **Trap:** giving prasugrel to an elderly patient or one with prior stroke. — **Correct:** its bleeding risk is highest in these groups, which is why it is not used there.

## Frequently asked questions

### Why is maintenance aspirin kept at 100 mg or less with ticagrelor?

Higher maintenance aspirin doses reduce the antiplatelet effect of ticagrelor, so aspirin is limited to 100 mg or less when ticagrelor is given. This is a classic examiner point in acute coronary syndrome management.

### Which P2Y12 inhibitor is preferred in acute coronary syndrome?

Ticagrelor or prasugrel is preferred over clopidogrel in acute coronary syndrome because they produce faster and more consistent platelet inhibition. Clopidogrel remains reasonable in stable disease or when the other agents are unsuitable or unaffordable.

### Which patients should not receive prasugrel?

Prasugrel should be avoided in patients with a previous stroke or transient ischaemic attack because it raises the risk of intracranial bleeding. It is also used with caution in those aged 75 or older and in patients weighing less than 60 kg.

### How long before elective surgery is clopidogrel stopped?

Clopidogrel is usually stopped about five days before elective surgery, because platelet function recovers only as new platelets are produced. Aspirin given for coronary disease is generally continued, and any change is decided with the cardiologist.