Moderate
Amiodarone × Diclofenac
Class III antiarrhythmics (Vaughan Williams)×Non-steroidal anti-inflammatory drugs (NSAIDs)
Mechanism
No direct pharmacokinetic interaction. Additive bleeding risk in patients on concurrent warfarin or amiodarone (the latter enhances anticoagulation via CYP2C9 inhibition).
Symptoms
Epigastric pain, heartburn, black or tarry stools, gum bleeding, bruising. Higher risk in older patients and prior peptic ulcer disease.
Management
For short diclofenac courses (3–7 days), no specific adjustment needed. For long-term needs, consider paracetamol up to 2 g/day, topical NSAIDs, or physiotherapy. Avoid NSAIDs on a warfarin-amiodarone regimen.