Drug interactions
Fostemsavir + Mirtazapine
Severity: Moderate
Fostemsavir and Mirtazapine: 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
Mirtazapine has been associated with QT prolongation, mainly in overdose or with other risk factors. Fostemsavir's active metabolite prolonged QTc at supratherapeutic doses, so combined use adds a modest theoretical arrhythmia risk.
What this interaction means in plain words
Fostemsavir and Mirtazapine 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 belongs to Anti Virals; Mirtazapine belongs to Central Nervous System.
Why it happens
Additive QTc interval prolongation.
What to do
Consider baseline and follow-up ECG in patients with other QT risk factors such as electrolyte disturbance, structural heart disease or additional 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 Mirtazapine
- Isocarboxazid + Mirtazapine Contraindicated
- Mirtazapine + Phenelzine Contraindicated
- Mirtazapine + Pimozide Contraindicated
- Mirtazapine + Procarbazine Contraindicated
- Mirtazapine + Rasagiline Contraindicated
- Mirtazapine + Selegiline Contraindicated
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 Fostemsavir with Mirtazapine?
MediHelp rates the interaction as moderate. Fostemsavir and Mirtazapine 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. Mirtazapine has been associated with QT prolongation, mainly in overdose or with other risk factors. Fostemsavir's active metabolite prolonged QTc at supratherapeutic doses, so combined use adds a modest theoretical arrhythmia risk.
How serious is the interaction between Fostemsavir and Mirtazapine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider baseline and follow-up ECG in patients with other QT risk factors such as electrolyte disturbance, structural heart disease or additional QT-prolonging drugs. Correct potassium and magnesium abnormalities.
What other medicines interact with Mirtazapine?
MediHelp also lists interactions of Mirtazapine with, for example, Isocarboxazid, Phenelzine, Pimozide. The full list is on the Mirtazapine page.
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