Major
Acetylsalicylic acid × Ibuprofen
Antiplatelet agents (low dose) / NSAIDs (analgesic dose)×Non-steroidal anti-inflammatory drugs (NSAIDs)
Mechanism
Ibuprofen reversibly binds platelet cyclooxygenase-1 and transiently blocks aspirin access for acetylation. When taken together, aspirin's cardioprotective effect is lost; antiplatelet protection fails.
Symptoms
The patient feels no symptoms. Recurrent myocardial infarction and ischaemic stroke risk rises in patients on low-dose aspirin for cardiovascular indications. GI bleeding risk from two NSAIDs persists.
Management
If the patient takes aspirin for cardioprotection, give aspirin 30 minutes before or 8 hours after ibuprofen (FDA 2006 recommendation). Alternative analgesic without this issue: paracetamol or a selective COX-2 inhibitor (celecoxib).