Acetylsalicylic acid × Rivaroxaban

Aspirin irreversibly blocks platelet cyclooxygenase; rivaroxaban directly inhibits factor Xa. No clinically significant pharmacokinetic or pharmacodynamic interaction was found with acetylsalicylic acid 500 mg. But the EMA SmPC lists acetylsalicylic acid among drugs that typically increase bleeding risk, and the effects on haemostasis add up.

Gum bleeding, epistaxis, bruising without trauma, blood in urine or stool, menorrhagia. Severe cases include gastrointestinal or intracranial haemorrhage. Risk rises in patients over 65 and with prior peptic ulcer disease.

The combination itself is an approved use of rivaroxaban. Rivaroxaban 2.5 mg twice daily with acetylsalicylic acid 75–100 mg daily is given after acute coronary syndrome (EMA SmPC). The same regimen is used in coronary artery disease or peripheral artery disease at high risk of ischaemic events (EMA SmPC and FDA label). The EMA SmPC contraindicates the combination in two groups: acute coronary syndrome in patients with prior stroke or transient ischaemic attack, and coronary or peripheral artery disease in patients with prior haemorrhagic or lacunar stroke or any stroke within the past month. On full-dose rivaroxaban (atrial fibrillation, deep vein thrombosis), add aspirin only for a separate indication and with caution. Patients at risk of peptic ulcer may receive gastric prophylaxis (EMA SmPC). Add NSAIDs to this pair only if the benefit outweighs the bleeding risk.