Moderate
Amlodipine × Fluoxetine
Calcium channel blockers (dihydropyridines)×Selective serotonin reuptake inhibitors
Mechanism
Fluoxetine and its active metabolite norfluoxetine moderately block CYP3A4 – the main amlodipine metabolic route. Amlodipine plasma levels may rise modestly. In older patients: additive hypotension.
Symptoms
Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.
Management
The combination is acceptable in most patients without dose change. In older patients, monitor blood pressure and hypotension symptoms 2 weeks after start.