Drug interactions
Nortriptyline + Phenobarbital
Severity: Moderate
Nortriptyline and Phenobarbital: 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
Both drugs depress the central nervous system, so combined use can cause excessive drowsiness and impaired psychomotor performance. Phenobarbital also induces hepatic enzymes and can lower nortriptyline concentrations, which may reduce antidepressant effect. Tricyclics can also lower the seizure threshold, which may counteract anticonvulsant control.
What this interaction means in plain words
Nortriptyline and Phenobarbital 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.
Why it happens
Additive CNS depression plus phenobarbital induction of CYP enzymes that metabolize nortriptyline.
What to do
Monitor sedation and clinical response to nortriptyline, and consider checking nortriptyline plasma levels if response is lost. Adjust the nortriptyline dose as needed and counsel patients about driving and alcohol.
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 Nortriptyline
- Disopyramide + Nortriptyline Contraindicated
- Dofetilide + Nortriptyline Contraindicated
- Dronedarone + Nortriptyline Contraindicated
- Ibutilide + Nortriptyline Contraindicated
- Isocarboxazid + Nortriptyline Contraindicated
- Methylene blue + Nortriptyline Contraindicated
Frequently asked questions
Can I take Nortriptyline with Phenobarbital?
MediHelp rates the interaction as moderate. Nortriptyline and Phenobarbital 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. Both drugs depress the central nervous system, so combined use can cause excessive drowsiness and impaired psychomotor performance. Phenobarbital also induces hepatic enzymes and can lower nortriptyline concentrations, which may reduce antidepressant effect. Tricyclics can also lower the seizure threshold, which may counteract anticonvulsant control.
How serious is the interaction between Nortriptyline and Phenobarbital?
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 sedation and clinical response to nortriptyline, and consider checking nortriptyline plasma levels if response is lost. Adjust the nortriptyline dose as needed and counsel patients about driving and alcohol.
What other medicines interact with Nortriptyline?
MediHelp also lists interactions of Nortriptyline with, for example, Disopyramide, Dofetilide, Dronedarone. The full list is on the Nortriptyline page.
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