Drug interactions
Amobarbital + Phenindione
Severity: Major
Amobarbital and Phenindione: 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
Amobarbital can reduce the anticoagulant effect of phenindione. Subtherapeutic anticoagulation increases thrombosis risk, and stopping the barbiturate later can cause overanticoagulation and bleeding.
What this interaction means in plain words
Amobarbital and Phenindione 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
Barbiturate induction of hepatic microsomal enzymes increases the metabolism of phenindione.
What to do
Avoid the combination if possible. If used together, monitor INR frequently and adjust the phenindione dose when amobarbital is started or stopped.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Amobarbital and Phenindione, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
References
- Dindevan 10mg Tablets - SmPC sections 4.3/4.5 (class statement: Barbiturates; "Barbiturates, Carbamazepine; Griseofulvin, Phenytoin.") — electronic medicines compendium (UK SmPC)
Other interactions of Amobarbital
- Amobarbital + Calcium / magnesium / potassium / sodium oxybates Contraindicated
- Amobarbital + Doravirine Contraindicated
- Amobarbital + Elbasvir / grazoprevir Contraindicated
- Amobarbital + Isavuconazonium Contraindicated
- Amobarbital + Isocarboxazid Contraindicated
- Amobarbital + Lonafarnib Contraindicated
Frequently asked questions
Can I take Amobarbital with Phenindione?
MediHelp rates the interaction as major. Amobarbital and Phenindione 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. Amobarbital can reduce the anticoagulant effect of phenindione. Subtherapeutic anticoagulation increases thrombosis risk, and stopping the barbiturate later can cause overanticoagulation and bleeding.
How serious is the interaction between Amobarbital and Phenindione?
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 the combination if possible. If used together, monitor INR frequently and adjust the phenindione dose when amobarbital is started or stopped.
What other medicines interact with Amobarbital?
MediHelp also lists interactions of Amobarbital with, for example, Calcium / magnesium / potassium / sodium oxybates, Doravirine, Elbasvir / grazoprevir. The full list is on the Amobarbital page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
