Moderate
Amlodipine × Sildenafil
Calcium channel blockers (dihydropyridines)×Phosphodiesterase type 5 inhibitors (PDE5)
Mechanism
Additive hypotension via different mechanisms – calcium channel blockade (amlodipine) + PDE5 blockade (sildenafil). Clinically significant in patients with prior hypotension.
Symptoms
Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.
Management
The combination is acceptable in stable hypertension. Take the first sildenafil dose lying down; do not exceed 25–50 mg. Warn the patient about orthostatic hypotension.