Drug interactions
Cinacalcet + Phenytoin
Severity: Moderate
Cinacalcet and Phenytoin: 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
Phenytoin is an inducer of CYP3A4 and may lower cinacalcet exposure. This could reduce the calcium-lowering effect and allow parathyroid hormone to rise.
What this interaction means in plain words
Cinacalcet and Phenytoin 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.
Cinacalcet belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing the metabolic clearance of cinacalcet.
What to do
Monitor serum calcium and PTH after starting or stopping phenytoin and increase the cinacalcet dose if response is lost. Reduce the dose again if phenytoin is withdrawn.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Other interactions of Cinacalcet
- Cinacalcet + Etelcalcetide Contraindicated
- Cinacalcet + Eliglustat Major
- Cinacalcet + Metoclopramide Major
- Cinacalcet + Metoclopramide intranasal Major
- Cinacalcet + Tamoxifen Major
- Abiraterone + Cinacalcet Moderate
Frequently asked questions
Can I take Cinacalcet with Phenytoin?
MediHelp rates the interaction as moderate. Cinacalcet and Phenytoin 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. Phenytoin is an inducer of CYP3A4 and may lower cinacalcet exposure. This could reduce the calcium-lowering effect and allow parathyroid hormone to rise.
How serious is the interaction between Cinacalcet and Phenytoin?
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 serum calcium and PTH after starting or stopping phenytoin and increase the cinacalcet dose if response is lost. Reduce the dose again if phenytoin is withdrawn.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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