Drug interactions
Clozapine + Fostemsavir
Severity: Moderate
Clozapine and Fostemsavir: 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
Fostemsavir has been linked to QT prolongation at supratherapeutic doses, and clozapine also prolongs the QT interval. The combination may add to arrhythmia risk, particularly in patients with other risk factors. At recommended fostemsavir doses the effect is expected to be small.
What this interaction means in plain words
Clozapine and Fostemsavir 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.
Clozapine belongs to Central Nervous System; Fostemsavir belongs to Anti Virals.
Why it happens
Additive QT interval prolongation.
What to do
Obtain a baseline ECG and monitor it in patients with risk factors such as cardiac disease, electrolyte disturbance or other QT-prolonging drugs. Correct potassium and magnesium abnormalities.
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 Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Other interactions of Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Fostemsavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Clozapine with Fostemsavir?
MediHelp rates the interaction as moderate. Clozapine and Fostemsavir 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. Fostemsavir has been linked to QT prolongation at supratherapeutic doses, and clozapine also prolongs the QT interval. The combination may add to arrhythmia risk, particularly in patients with other risk factors. At recommended fostemsavir doses the effect is expected to be small.
How serious is the interaction between Clozapine and Fostemsavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG and monitor it in patients with risk factors such as cardiac disease, electrolyte disturbance or other QT-prolonging drugs. Correct potassium and magnesium abnormalities.
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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