Drug interactions
Istradefylline + Norethisterone
Severity: Minor
Istradefylline and Norethisterone: 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 sensitive substrates; this was not seen at 20 mg daily. Any rise in norethisterone levels is expected to be small.
What this interaction means in plain words
Istradefylline and Norethisterone 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; Norethisterone belongs to Endocrine.
Why it happens
Dose-dependent CYP3A4 inhibition by istradefylline reduces norethisterone clearance.
What to do
No routine change is needed; monitor for increased progestogenic adverse effects, especially if istradefylline 40 mg daily is used.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Istradefylline and Norethisterone, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Norethisterone
- Acitretin + Norethisterone Contraindicated
- Amobarbital + Norethisterone Major
- Apalutamide + Norethisterone Major
- Belzutifan + Norethisterone Major
- Bosentan + Norethisterone Major
- Brigatinib + Norethisterone Major
Other interactions of Istradefylline
Frequently asked questions
Can I take Istradefylline with Norethisterone?
MediHelp rates the interaction as minor. Istradefylline and Norethisterone 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 sensitive substrates; this was not seen at 20 mg daily. Any rise in norethisterone levels is expected to be small.
How serious is the interaction between Istradefylline and Norethisterone?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine change is needed; monitor for increased progestogenic adverse effects, especially if istradefylline 40 mg daily is used.
What other medicines interact with Norethisterone?
MediHelp also lists interactions of Norethisterone with, for example, Acitretin, Amobarbital, Apalutamide. The full list is on the Norethisterone page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
