Drug interactions
Clozapine + Fosaprepitant
Severity: Minor
Clozapine and Fosaprepitant: 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
Fosaprepitant is converted to aprepitant, a moderate CYP3A4 inhibitor, which may raise clozapine levels transiently. With a single dose the effect is likely small, since clozapine is mainly cleared by CYP1A2. Both drugs may also affect QT in susceptible patients.
What this interaction means in plain words
Clozapine and Fosaprepitant have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Clozapine belongs to Central Nervous System; Fosaprepitant belongs to Gastrointestinal Tract.
Why it happens
Temporary inhibition of CYP3A4 by aprepitant slightly reduces clozapine clearance.
What to do
No dose change is generally needed for single-dose use; watch for sedation or hypotension in the days after dosing. Consider a clozapine level if multi-day regimens are repeated.
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 Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Other interactions of Fosaprepitant
- Flibanserin + Fosaprepitant Contraindicated
- Fosaprepitant + Pimozide Contraindicated
- Alprazolam + Fosaprepitant Moderate
- Amiodarone + Fosaprepitant Moderate
- Amobarbital + Fosaprepitant Moderate
- Apalutamide + Fosaprepitant Moderate
Frequently asked questions
Can I take Clozapine with Fosaprepitant?
MediHelp rates the interaction as minor. Clozapine and Fosaprepitant have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Fosaprepitant is converted to aprepitant, a moderate CYP3A4 inhibitor, which may raise clozapine levels transiently. With a single dose the effect is likely small, since clozapine is mainly cleared by CYP1A2. Both drugs may also affect QT in susceptible patients.
How serious is the interaction between Clozapine and Fosaprepitant?
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 dose change is generally needed for single-dose use; watch for sedation or hypotension in the days after dosing. Consider a clozapine level if multi-day regimens are repeated.
What other medicines interact with Clozapine?
MediHelp also lists interactions of Clozapine with, for example, Deferiprone, Irinotecan, Pimozide. The full list is on the Clozapine page.
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