Drug interactions
Liothyronine + Selpercatinib
Severity: Moderate
Liothyronine and Selpercatinib: 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
Selpercatinib has been associated with reduced efficacy of levothyroxine, probably because it impairs peripheral conversion of T4 to T3. Patients on thyroid replacement may develop hypothyroid features. Liothyronine, which supplies T3 directly, may be needed to restore thyroid status.
What this interaction means in plain words
Liothyronine and Selpercatinib 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.
Liothyronine belongs to Endocrine; Selpercatinib belongs to Oncology.
Why it happens
Selpercatinib may inhibit deiodinase-mediated peripheral conversion of T4 to T3, so liothyronine bypasses this step.
What to do
Monitor TSH and free T3/T4 after starting selpercatinib in patients on thyroid replacement. Adjust the thyroid regimen, including adding liothyronine, according to results and symptoms.
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 Selpercatinib
Other interactions of Liothyronine
- Alogliptin-metformin + Liothyronine Moderate
- Amitriptyline + Liothyronine Moderate
- Amobarbital + Liothyronine Moderate
- Canagliflozin-metformin + Liothyronine Moderate
- Carbamazepine + Liothyronine Moderate
- Carbonyl iron + Liothyronine Moderate
Frequently asked questions
Can I take Liothyronine with Selpercatinib?
MediHelp rates the interaction as moderate. Liothyronine and Selpercatinib 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. Selpercatinib has been associated with reduced efficacy of levothyroxine, probably because it impairs peripheral conversion of T4 to T3. Patients on thyroid replacement may develop hypothyroid features. Liothyronine, which supplies T3 directly, may be needed to restore thyroid status.
How serious is the interaction between Liothyronine and Selpercatinib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor TSH and free T3/T4 after starting selpercatinib in patients on thyroid replacement. Adjust the thyroid regimen, including adding liothyronine, according to results and symptoms.
What other medicines interact with Selpercatinib?
MediHelp also lists interactions of Selpercatinib with, for example, Amiodarone, Amisulpride, Amitriptyline. The full list is on the Selpercatinib page.
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