Drug interactions
Fostemsavir + Loperamide
Severity: Moderate
Fostemsavir and Loperamide: 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
Both drugs can prolong the QT interval; fostemsavir does so mainly at supratherapeutic doses, while loperamide does so mainly in overdose or misuse. The combined risk of arrhythmia such as torsades de pointes is small at standard doses but rises with high loperamide use.
What this interaction means in plain words
Fostemsavir and Loperamide 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; Loperamide belongs to Gastrointestinal Tract.
Why it happens
Additive QT prolongation through cardiac potassium channel (hERG) effects.
What to do
Keep loperamide at labeled doses and avoid high-dose use; consider ECG monitoring in patients with other QT risk factors or electrolyte 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 Loperamide
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 Loperamide?
MediHelp rates the interaction as moderate. Fostemsavir and Loperamide 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. Both drugs can prolong the QT interval; fostemsavir does so mainly at supratherapeutic doses, while loperamide does so mainly in overdose or misuse. The combined risk of arrhythmia such as torsades de pointes is small at standard doses but rises with high loperamide use.
How serious is the interaction between Fostemsavir and Loperamide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Keep loperamide at labeled doses and avoid high-dose use; consider ECG monitoring in patients with other QT risk factors or electrolyte abnormalities.
What other medicines interact with Loperamide?
MediHelp also lists interactions of Loperamide with, for example, Amiodarone, Amisulpride, Anagrelide. The full list is on the Loperamide page.
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