Drug interactions
Carbamazepine + Olanzapine / samidorphan
Severity: Major
Carbamazepine and Olanzapine / samidorphan: 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
Carbamazepine markedly lowers plasma levels of both olanzapine and samidorphan. This can reduce antipsychotic efficacy and weaken the opioid antagonist effect that mitigates weight gain.
What this interaction means in plain words
Carbamazepine and Olanzapine / samidorphan 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
Carbamazepine induces CYP3A4 (and other enzymes such as CYP1A2 and UGT) and accelerates clearance of both components.
What to do
Avoid concomitant use per labeling and consider an alternative mood stabilizer or anticonvulsant. If it cannot be avoided, monitor psychiatric 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 Carbamazepine
- Artemether / lumefantrine + Carbamazepine Contraindicated
- Cabotegravir + Carbamazepine Contraindicated
- Carbamazepine + Delamanid Contraindicated
- Carbamazepine + Dienogest / estradiol valerate Contraindicated
- Carbamazepine + Doravirine Contraindicated
- Carbamazepine + Elbasvir / grazoprevir Contraindicated
Frequently asked questions
Can I take Carbamazepine with Olanzapine / samidorphan?
MediHelp rates the interaction as major. Carbamazepine and Olanzapine / samidorphan 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. Carbamazepine markedly lowers plasma levels of both olanzapine and samidorphan. This can reduce antipsychotic efficacy and weaken the opioid antagonist effect that mitigates weight gain.
How serious is the interaction between Carbamazepine and Olanzapine / samidorphan?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid concomitant use per labeling and consider an alternative mood stabilizer or anticonvulsant. If it cannot be avoided, monitor psychiatric response closely.
What other medicines interact with Carbamazepine?
MediHelp also lists interactions of Carbamazepine with, for example, Artemether / lumefantrine, Cabotegravir, Delamanid. The full list is on the Carbamazepine page.
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