Drug interactions
Pitolisant + Promethazine
Severity: Moderate
Pitolisant and Promethazine: moderate 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
Pitolisant is an H3 receptor inverse agonist that promotes wakefulness by increasing brain histamine. Promethazine is a centrally acting H1 antagonist and can counteract this effect, reducing pitolisant's efficacy.
What this interaction means in plain words
Pitolisant and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Pitolisant belongs to Central Nervous System; Promethazine belongs to Respiratory.
Why it happens
Pharmacodynamic antagonism, with central H1 receptor blockade by promethazine opposing histamine-mediated wakefulness.
What to do
Avoid centrally acting sedating antihistamines in patients taking pitolisant. Use a non-sedating alternative and monitor control of narcolepsy symptoms.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Other interactions of Pitolisant
- Alfuzosin + Pitolisant Major
- Amiodarone + Pitolisant Major
- Amisulpride + Pitolisant Major
- Anagrelide + Pitolisant Major
- Asenapine + Pitolisant Major
- Bupropion + Pitolisant Major
Frequently asked questions
Can I take Pitolisant with Promethazine?
MediHelp rates the interaction as moderate. Pitolisant and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Pitolisant is an H3 receptor inverse agonist that promotes wakefulness by increasing brain histamine. Promethazine is a centrally acting H1 antagonist and can counteract this effect, reducing pitolisant's efficacy.
How serious is the interaction between Pitolisant and Promethazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid centrally acting sedating antihistamines in patients taking pitolisant. Use a non-sedating alternative and monitor control of narcolepsy symptoms.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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