Drug interactions
Fostamatinib + Loperamide
Severity: Moderate
Fostamatinib 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
Fostamatinib's active metabolite R406 inhibits P-glycoprotein and can raise exposure to P-gp substrates such as loperamide. Higher loperamide levels may increase constipation and, at high exposure, central opioid effects and cardiac toxicity.
What this interaction means in plain words
Fostamatinib 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.
Fostamatinib belongs to Oncology; Loperamide belongs to Gastrointestinal Tract.
Why it happens
R406 inhibits P-gp efflux, increasing intestinal absorption and reducing loperamide efflux across the blood-brain barrier.
What to do
Use the lowest effective loperamide dose and avoid exceeding labeled maximums; watch for constipation, abdominal distension, sedation and palpitations.
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 Fostamatinib
- Colchicine + Fostamatinib Major
- Fostamatinib + Phenytoin Major
- Amobarbital + Fostamatinib Moderate
- Apalutamide + Fostamatinib Moderate
- Atorvastatin + Fostamatinib Moderate
- Bosentan + Fostamatinib Moderate
Frequently asked questions
Can I take Fostamatinib with Loperamide?
MediHelp rates the interaction as moderate. Fostamatinib 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. Fostamatinib's active metabolite R406 inhibits P-glycoprotein and can raise exposure to P-gp substrates such as loperamide. Higher loperamide levels may increase constipation and, at high exposure, central opioid effects and cardiac toxicity.
How serious is the interaction between Fostamatinib 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: Use the lowest effective loperamide dose and avoid exceeding labeled maximums; watch for constipation, abdominal distension, sedation and palpitations.
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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