Drug interactions
Saquinavir + Tadalafil
Severity: Major
Saquinavir and Tadalafil: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Saquinavir, usually boosted with ritonavir, inhibits CYP3A4 and can raise tadalafil exposure considerably. This increases the risk of hypotension, visual disturbance, priapism and other adverse effects.
What this interaction means in plain words
Saquinavir and Tadalafil can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Saquinavir inhibits CYP3A4, reducing tadalafil clearance.
What to do
For erectile dysfunction, limit tadalafil to 2.5 mg daily or 10 mg no more often than every 72 hours. Avoid in pulmonary arterial hypertension unless carefully dose-adjusted.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Tadalafil
- Amyl nitrite + Tadalafil Contraindicated
- Isosorbide dinitrate + Tadalafil Contraindicated
- Isosorbide mononitrate + Tadalafil Contraindicated
- Nitroglycerin po + Tadalafil Contraindicated
- Nitroglycerin rectal + Tadalafil Contraindicated
- Nitroglycerin sublingual + Tadalafil Contraindicated
Frequently asked questions
Can I take Saquinavir with Tadalafil?
MediHelp rates the interaction as major. Saquinavir and Tadalafil can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Saquinavir, usually boosted with ritonavir, inhibits CYP3A4 and can raise tadalafil exposure considerably. This increases the risk of hypotension, visual disturbance, priapism and other adverse effects.
How serious is the interaction between Saquinavir and Tadalafil?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: For erectile dysfunction, limit tadalafil to 2.5 mg daily or 10 mg no more often than every 72 hours. Avoid in pulmonary arterial hypertension unless carefully dose-adjusted.
What other medicines interact with Tadalafil?
MediHelp also lists interactions of Tadalafil with, for example, Amyl nitrite, Isosorbide dinitrate, Isosorbide mononitrate. The full list is on the Tadalafil page.
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