Drug interactions
Chlordiazepoxide + Phenobarbital
Severity: Major
Chlordiazepoxide and Phenobarbital: major interaction.
Last updated Sources: UK SmPC
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 and chlordiazepoxide cause additive sedation and respiratory depression. Phenobarbital also induces hepatic enzymes and can reduce chlordiazepoxide levels over time.
What this interaction means in plain words
Chlordiazepoxide and Phenobarbital 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
Additive GABA-A mediated CNS depression plus phenobarbital induction of CYP3A4 and other hepatic enzymes.
What to do
Avoid combining unless intended, as in supervised alcohol withdrawal or seizure management. Monitor sedation and respiratory status and reassess benzodiazepine dose as induction develops or wanes.
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
- Librium 10 mg Capsules - SmPC sections 4.3/4.5 (class statement: barbiturates; "particularly with hydantoins or barbiturates or combinations including them.") — electronic medicines compendium (UK SmPC)
Other interactions of Chlordiazepoxide
Frequently asked questions
Can I take Chlordiazepoxide with Phenobarbital?
MediHelp rates the interaction as major. Chlordiazepoxide and Phenobarbital 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. Phenobarbital and chlordiazepoxide cause additive sedation and respiratory depression. Phenobarbital also induces hepatic enzymes and can reduce chlordiazepoxide levels over time.
How serious is the interaction between Chlordiazepoxide and Phenobarbital?
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 combining unless intended, as in supervised alcohol withdrawal or seizure management. Monitor sedation and respiratory status and reassess benzodiazepine dose as induction develops or wanes.
What other medicines interact with Chlordiazepoxide?
MediHelp also lists interactions of Chlordiazepoxide with, for example, Alfentanil, Alprazolam, Amobarbital. The full list is on the Chlordiazepoxide page.
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