CriticalLong-acting organic nitrate×Phosphodiesterase type 5 inhibitors (PDE5)
Updated · Methodology
Mechanism
Sildenafil inhibits PDE-5; isosorbide mononitrate releases nitric oxide. Both pathways converge on cGMP accumulation in vascular smooth muscle, causing severe systemic vasodilation. Blood pressure drops to shock levels with risk of myocardial infarction and stroke. FDA contraindicates PDE-5 inhibitors with any nitrate.
Symptoms
Sudden hypotension within an hour: dizziness, syncope, tachycardia, pallor, loss of consciousness. Cardiac arrest possible.
Management
Combination contraindicated. Allow at least 24 hours between the last sildenafil dose and any nitrate (48 hours for tadalafil). A patient with angina who has taken sildenafil should not receive nitrates – use morphine, oxygen and urgent angiography.
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 →
Medicine list: everything you take in one place →
Sources
- FDA: Viagra section 7 (2014)– ; DailyMed setid 0b0be196-0c62-461c-94f4-9a35339b4501
- AEMPS: Ficha técnica: Mononitrato de isosorbida (nº registro 63397), sección 4.3 (2022)– AEMPS, CIMA, nº registro 63397, revisión 02/2022, sección 4.3