MajorCentral α2-adrenergic agonist×Phosphodiesterase type 5 inhibitors (PDE5)
Updated · Methodology
Mechanism
Additive hypotensive effect. Sildenafil vasodilates by blocking phosphodiesterase-5; clonidine lowers blood pressure via central α2-agonism. Combined action can cause symptomatic hypotension.
Symptoms
Sudden blood pressure drop: postural dizziness, syncope. Particularly dangerous in older patients and in ischaemic heart disease.
Management
The combination is acceptable in stable hypertension. Cap sildenafil at 25 mg (instead of 50–100 mg). Warn the patient about orthostatic hypotension; take the first dose lying down.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
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Sources
- FDA: Viagra section 7 (2014)– ; DailyMed setid 0b0be196-0c62-461c-94f4-9a35339b4501