Drug interactions
Pentobarbital + Promethazine
Severity: Major
Pentobarbital and Promethazine: major 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
Pentobarbital is a barbiturate with strong sedative and respiratory depressant effects. Promethazine adds sedation and may increase the risk of excessive CNS depression and hypotension.
What this interaction means in plain words
Pentobarbital and Promethazine 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 CNS depression from GABA-A potentiation and H1 receptor blockade.
What to do
Reduce doses and monitor level of consciousness, respiratory rate and blood pressure. Avoid in patients with compromised respiratory function unless monitoring is available.
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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Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Frequently asked questions
Can I take Pentobarbital with Promethazine?
MediHelp rates the interaction as major. Pentobarbital and Promethazine 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. Pentobarbital is a barbiturate with strong sedative and respiratory depressant effects. Promethazine adds sedation and may increase the risk of excessive CNS depression and hypotension.
How serious is the interaction between Pentobarbital and Promethazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Reduce doses and monitor level of consciousness, respiratory rate and blood pressure. Avoid in patients with compromised respiratory function unless monitoring is available.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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