Drug interactions
Lorlatinib + Nafcillin
Severity: Major
Lorlatinib and Nafcillin: major 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
Nafcillin can induce CYP3A4 and lower lorlatinib exposure. Lorlatinib labeling contraindicates strong CYP3A inducers because of loss of efficacy and hepatotoxicity seen in healthy volunteers with rifampin. Nafcillin is a weaker or moderate inducer, but the loss of efficacy risk remains.
What this interaction means in plain words
Lorlatinib and Nafcillin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Induction of CYP3A4 increases the metabolism of lorlatinib, reducing its plasma concentrations.
What to do
Prefer a non-inducing antibiotic alternative. If nafcillin is essential, monitor liver enzymes and the tumour response closely.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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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 Nafcillin?
MediHelp rates the interaction as major. Lorlatinib and Nafcillin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Nafcillin can induce CYP3A4 and lower lorlatinib exposure. Lorlatinib labeling contraindicates strong CYP3A inducers because of loss of efficacy and hepatotoxicity seen in healthy volunteers with rifampin. Nafcillin is a weaker or moderate inducer, but the loss of efficacy risk remains.
How serious is the interaction between Lorlatinib and Nafcillin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer a non-inducing antibiotic alternative. If nafcillin is essential, monitor liver enzymes and the tumour response closely.
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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