01Purpose and principlesWhat the treatment does and how it fits into care.
Antiplatelet drugs reduce platelet-driven arterial thrombosis. Aspirin inhibits thromboxane generation, while clopidogrel and ticagrelor act through the platelet P2Y12 receptor. Combining mechanisms can improve protection during periods of high coronary thrombotic risk, but it also makes bleeding more likely. The net benefit changes over time: the days after a coronary intervention are not equivalent to several years after an uncomplicated myocardial infarction. A useful prescription therefore contains a temporal story. It identifies why treatment began, which early phase has already been completed, how long a combination is intended to continue, and which medicine remains afterwards. Without that story, repeat prescribing can perpetuate a combination long after its intended review.
Clinical decisions about antiplatelets cannot be made from tablet strength alone. A person taking aspirin 75 mg might have coronary disease, cerebrovascular disease, a pregnancy-related prevention indication or an outdated primary-prevention prescription. Another patient taking both aspirin and clopidogrel may have a deliberate short course, a recent stent or accidental duplication. Ask for the discharge plan and intervention record before inferring the reason. Likewise, bleeding should be described precisely: a small stable bruise, recurrent melaena and suspected intracranial haemorrhage demand different responses. Safe practice combines immediate assessment of the presenting problem with protection against the consequences of an unnecessary or prolonged interruption.
Key points
- Identify the event, intervention and date: acute coronary syndrome, coronary stent and previous non-cardioembolic stroke do not automatically share the same antiplatelet plan.
- For acute coronary syndrome, NICE recommends aspirin 300 mg orally as a loading dose unless clearly contraindicated; after myocardial infarction, aspirin is generally continued at 75 mg orally once daily indefinitely unless unsuitable.
- When ticagrelor is selected for ACS, its UK SmPC regimen is 180 mg orally once, then 90 mg orally twice daily, usually for 12 months, with low-dose aspirin unless a specialist-led alternative applies.
- Clopidogrel 75 mg orally once daily is a common maintenance regimen for established atherothrombotic disease. Any loading dose and combination duration must follow the actual acute indication and intervention pathway.
- Dual antiplatelet therapy means aspirin plus a P2Y12 inhibitor. Combining either with anticoagulation further increases bleeding risk and needs an explicit specialist indication, duration and review.
- Avoid omeprazole and esomeprazole with clopidogrel; if gastroprotection is needed, select a suitable alternative PPI such as lansoprazole or pantoprazole after reviewing the indication.
- Do not abruptly stop recent stent therapy for bruising, dental work or an uncoordinated procedure request. Assess urgency and bleeding severity, then agree interruption and restart with the responsible team.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
Distinguish established atherosclerotic disease from atrial-fibrillation embolic risk and from primary prevention. An antiplatelet does not supply equivalent stroke protection when oral anticoagulation is indicated for atrial fibrillation. Ask whether the documented stroke was haemorrhagic, cardioembolic or non-cardioembolic before renewing an apparently familiar medicine. The diagnostic label determines which guidance applies.
Determine the date of acute coronary syndrome, whether PCI or surgery occurred, the intended P2Y12 agent and the planned duration. A person may correctly receive a different regimen from a neighbour with the same diagnosis because bleeding risk, anticoagulation and the intervention differ. Recover the cardiology plan rather than averaging several guideline pathways into one.
Ask about melaena, haematemesis, haematuria, severe headache, falls and increasing fatigue, as well as nuisance bruising. Ticagrelor-associated dyspnoea is possible, but new breathlessness after an infarction also raises heart failure, recurrent ischaemia and pulmonary embolism. Do not assign a drug adverse effect until urgent alternative causes have been assessed appropriately.
Include NSAIDs, oral anticoagulants, corticosteroids and serotonergic medicines in a bleeding-risk review. Ask directly about non-prescription ibuprofen and combination cold or pain remedies. For clopidogrel, examine the particular PPI rather than treating all acid suppression as identical. An interaction review should produce a practical replacement or monitoring plan, not an unexplained warning on the record.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Full blood count with previous valuesFirst step - Why
- Assess anaemia and platelet count before or during treatment review.
- Interpretation and limitations
- A declining haemoglobin may be clinically significant even if the current result remains inside the laboratory reference range. Interpret it alongside symptoms, fluid status and recent procedures. Thrombocytopenia requires a cause and treatment discussion; it cannot be resolved merely by choosing a different brand of aspirin.
- 02
Kidney function and hepatic assessment - Why
- Identify comorbidity that increases bleeding or limits agent suitability.
- Interpretation and limitations
- Renal impairment changes overall bleeding risk and may influence the wider ACS strategy even where a specific antiplatelet does not require routine renal dose reduction. Severe hepatic impairment is a contraindication to ticagrelor. Review the actual product and patient rather than inferring safety from the absence of an INR requirement.
- 03
Electrocardiogram and acute assessment when symptomatic - Why
- Investigate new chest pain, syncope or breathlessness appropriately.
- Interpretation and limitations
- Medication reconciliation must not delay assessment for a recurrent coronary event. A patient who missed several doses after PCI may need urgent specialist evaluation, but a normal single ECG does not settle that risk. Interpret serial clinical findings and investigations through the acute coronary pathway.
- 04
Discharge documentation and dispensing history - Why
- Verify the intended combination and detect unintended continuation or gaps.
- Interpretation and limitations
- The most valuable missing information may be a cardiology letter rather than a laboratory test. Compare the event date, medicine list, documented stop date and actual supply. A repeat template that predates admission should not overrule a clear subsequent specialist decision without clinical review.
04Treatment approachPreparation, options, escalation and aftercare.
01InitiationPrescribe after an acute coronary eventFirst stepAn adult has an agreed ACS treatment strategy and can receive oral medicines.+
- 1Check whether aspirin and a P2Y12 loading dose have already been administered by ambulance, emergency department or catheter laboratory staff. Obtain the administration record before prescribing another loading dose; a second prescription does not necessarily mean a second dose is required.
- 2Use the NICE strategy appropriate to the infarct presentation, intervention and anticoagulant status. When ticagrelor is selected, ensure its loading and twice-daily maintenance schedule match the product and the clinical plan, including aspirin co-treatment where intended.
- 3Record the maintenance medicines, start date, planned combination duration and responsible reviewing team. State any reason for a shortened or modified strategy so that a community prescriber does not automatically restore a standard but inappropriate combination.
- 4Before discharge, ask the patient to explain which medicine is taken once daily and which twice daily, how supply will continue and whom to contact about bleeding. Include clear advice that stopping recent stent treatment needs coordinated assessment.
02ReconciliationResolve an antiplatelet and PPI interactionA person taking clopidogrel is found to be taking omeprazole.+
- 1Confirm the clopidogrel indication and whether acid suppression remains justified by gastrointestinal history, concurrent medicines or another diagnosis. Neither medicine should be reflexively removed before understanding the clinical purpose of both.
- 2AlternativeExplain that omeprazole and esomeprazole can reduce activation of clopidogrel. If a PPI is still needed, choose an appropriate alternative such as lansoprazole or pantoprazole using its own dose and indication guidance, and document the change.
- 3Update the repeat list, discharge record and pharmacy supply so that the old PPI does not return through an automated refill. Check over-the-counter use and combination packaging, which may otherwise leave the interaction in place.
- 4Review symptoms and ongoing gastroprotection need at a suitable interval. Switching the interacting PPI addresses one hazard; it does not eliminate gastrointestinal bleeding risk from antiplatelets, anticoagulants or NSAIDs.
03Safety reviewManage a proposed interruption after coronary stentingA patient with a recent stent needs a procedure or reports bleeding.+
- 1Classify the problem first: active life-threatening bleeding needs emergency treatment, while minor bruising or an elective procedure allows coordinated planning. Establish the stent date, complete regimen, last doses and the consequences of delay.
- 2Contact the responsible cardiology and procedural teams to agree whether treatment can continue, which agent might need interruption, and the timing. Do not rely on an unspecific instruction to stop all blood thinners, especially when anticoagulants are also prescribed.
- 3Give the patient a written plan that names each medicine and its stop and restart dates, including what to do if the procedure is cancelled. Make one team accountable for any unresolved decision before the patient leaves.
- 4After the event, reconcile actual administration against the plan and confirm resumption or the documented long-term change. An uncompleted restart instruction is a medication error even if the original interruption was appropriate.
05Regimens, contraindications and interactionsTreatment details and the circumstances that modify them.
Aspirin in acute coronary syndrome and after myocardial infarction
NICE ACS loading: 300 mg orally once unless contraindicated. After myocardial infarction, maintenance is generally 75 mg orally once daily indefinitely unless an alternative is required.Confirm prior loading, true allergy and active bleeding. Combined treatment and procedure decisions depend on the specialist plan; assess gastrointestinal protection and avoid casually adding over-the-counter NSAIDs.
Ticagrelor for selected acute coronary syndromes
UK SmPC: 180 mg orally as one loading dose, then 90 mg orally twice daily, generally for 12 months; usually with aspirin 75–150 mg daily unless a documented specialist strategy differs.Avoid active pathological bleeding, previous intracranial haemorrhage, severe hepatic impairment and strong CYP3A4 inhibitors. Assess dyspnoea and bradyarrhythmia symptoms; extended 60 mg twice-daily therapy is a separate selected indication.
Clopidogrel for established atherothrombotic disease
75 mg orally once daily as maintenance; duration follows the vascular indication. Acute loading and combination schedules require the specific stroke or coronary pathway.Contraindicated in active pathological bleeding or severe hepatic impairment; use caution in moderate hepatic disease with a bleeding diathesis. Omeprazole and esomeprazole impair activation; pregnancy or breastfeeding requires individual specialist assessment rather than assuming class interchangeability.
06Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- Ask at follow-up about bleeding that the patient may have normalised, including dark stools and persistent epistaxis. Relate symptoms to haemoglobin trends and functional change; prolonged fatigue may be a presentation of blood loss rather than recovery from the original event.
- Review adherence in a non-judgemental way, especially when twice-daily treatment, breathlessness or prescription costs in the relevant setting create barriers. Identifying the reason for missed doses enables a safer plan than simply documenting non-compliance.
- Check the antiplatelet combination at each anticoagulant initiation, hospital transfer and procedural referral. Name the clinician responsible for any overlap and put the stop or reassessment date where repeat prescribers will see it.
- At the intended end of dual therapy, confirm the future regimen rather than stopping both agents by accident. Some people need an extended specialist strategy; others need removal of an unnecessary second agent after the planned course.
07Special situationsVariants, exceptions and circumstances that change the usual approach.
A loading dose solves a timing problem
Loading achieves the desired antiplatelet effect earlier than maintenance alone. It is not a larger daily dose to be repeated at every transfer. Trace actual administrations when the patient passes through several acute teams.
Primary prevention requires a separate decision
The familiarity of low-dose aspirin should not turn an undocumented preventive prescription into lifelong treatment. Establish whether there is known vascular disease and review an unclear indication against current guidance and the individual bleeding risk.
Dyspnoea needs clinical interpretation
Ticagrelor can be associated with breathlessness, but a recent ACS patient has several serious competing explanations. Timing, examination and targeted investigation help distinguish an adverse effect from deterioration that needs urgent treatment.
Stopping is an active prescription decision
A planned end date is useful only if it reaches the medication record and the person taking the tablets. Verify that the supply system implements the decision and that any retained antiplatelet remains available.
08Common pitfallsFrequent interpretation and management errors.
- 01
Giving aspirin 300 mg again because an ambulance dose is absent from the ward chart ignores an administration that may already have occurred.
- 02
Treating every PPI as equivalent with clopidogrel misses a medicine-specific interaction that can usually be addressed while preserving needed gastroprotection.
- 03
Stopping all antithrombotic medicines for an elective procedure without establishing the stent history can expose the patient to avoidable thrombosis.
- 04
Renewing dual antiplatelet therapy indefinitely because no stop date appears on a repeat screen transfers an unresolved decision into every subsequent prescription.