Drug interactions
Lorlatinib + Phenobarbital
Severity: Contraindicated
Lorlatinib and Phenobarbital: contraindicated interaction.
Last updated Sources: US FDA label
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
Phenobarbital strongly induces CYP3A4 and can substantially reduce lorlatinib exposure, compromising anticancer efficacy. Strong inducers combined with lorlatinib have also produced hepatotoxicity. The combination is contraindicated in labeling.
What this interaction means in plain words
Lorlatinib and Phenobarbital are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Why it happens
Induction of CYP3A4 increases lorlatinib clearance.
What to do
Avoid the combination and use a non-inducing anticonvulsant such as levetiracetam. Allow washout of about 3 inducer half-lives before starting lorlatinib.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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References
Other interactions of Lorlatinib
- Amobarbital + Lorlatinib Contraindicated
- Apalutamide + Lorlatinib Contraindicated
- Butabarbital + Lorlatinib Contraindicated
- Carbamazepine + Lorlatinib Contraindicated
- Enzalutamide + Lorlatinib Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
Frequently asked questions
Can I take Lorlatinib with Phenobarbital?
MediHelp rates the interaction as contraindicated. Lorlatinib and Phenobarbital are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Phenobarbital strongly induces CYP3A4 and can substantially reduce lorlatinib exposure, compromising anticancer efficacy. Strong inducers combined with lorlatinib have also produced hepatotoxicity. The combination is contraindicated in labeling.
How serious is the interaction between Lorlatinib and Phenobarbital?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and use a non-inducing anticonvulsant such as levetiracetam. Allow washout of about 3 inducer half-lives before starting lorlatinib.
What other medicines interact with Lorlatinib?
MediHelp also lists interactions of Lorlatinib with, for example, Amobarbital, Apalutamide, Butabarbital. The full list is on the Lorlatinib page.
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