Drug interactions
Istradefylline + Sildenafil
Severity: Minor
Istradefylline and Sildenafil: minor 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
At 40 mg daily istradefylline weakly inhibits CYP3A4 and can increase exposure to CYP3A4 substrates such as sildenafil. At 20 mg daily the effect has not been observed.
What this interaction means in plain words
Istradefylline and Sildenafil have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Istradefylline belongs to Central Nervous System; Sildenafil belongs to Genitourinary.
Why it happens
Dose-dependent CYP3A4 inhibition by istradefylline reduces sildenafil metabolism.
What to do
Consider a reduced sildenafil starting dose if istradefylline 40 mg daily is used, and monitor for hypotension and other adverse effects.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Sildenafil
- Amyl nitrite + Sildenafil Contraindicated
- Atazanavir + Sildenafil Contraindicated
- Cobicistat + Sildenafil Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Sildenafil Contraindicated
- Glyceryl trinitrate pr + Sildenafil Contraindicated
- Isosorbide dinitrate + Sildenafil Contraindicated
Other interactions of Istradefylline
Frequently asked questions
Can I take Istradefylline with Sildenafil?
MediHelp rates the interaction as minor. Istradefylline and Sildenafil have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. At 40 mg daily istradefylline weakly inhibits CYP3A4 and can increase exposure to CYP3A4 substrates such as sildenafil. At 20 mg daily the effect has not been observed.
How serious is the interaction between Istradefylline and Sildenafil?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider a reduced sildenafil starting dose if istradefylline 40 mg daily is used, and monitor for hypotension and other adverse effects.
What other medicines interact with Sildenafil?
MediHelp also lists interactions of Sildenafil with, for example, Amyl nitrite, Atazanavir, Cobicistat. The full list is on the Sildenafil page.
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