[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antiseizure medicines](https://durgical.com/en/pharmacology/classes/antiseizure-medicines/) › Felbamate

[Pharmacology](https://durgical.com/en/pharmacology/) · [Antiseizure medicines](https://durgical.com/en/pharmacology/classes/antiseizure-medicines/)

# Felbamate

A last-resort antiseizure medicine for severe epilepsy. It can cause aplastic anaemia and liver failure, so it is used only when the benefit justifies it.

Updated 2026-11-01

- Class: [Antiseizure medicines](https://durgical.com/en/pharmacology/classes/antiseizure-medicines/)
- Receptor: NMDA receptor, glycine site (GluN1)
- ATC code: N03AX10

## Mechanism of action

Felbamate blocks the NMDA type of glutamate receptor by acting at its strychnine-insensitive glycine site, reducing excitatory signalling. Its exact antiseizure mechanism is not fully known.

- Acts at the glycine site of the NMDA receptor
- NMDA-mediated excitation is reduced
- Neuronal hyperexcitability falls
- Severe seizures become less frequent

## Pharmacokinetics

**Absorption**
Absorbed by mouth

**Elimination**
Partly by the kidneys; clearance falls and half-life lengthens in kidney disease

**Half-life**
About 20 to 23 hours

## Indications

- Severe focal seizures in adults not controlled by other medicines [Epilepsy and seizures →](https://durgical.com/en/conditions/epilepsy-and-seizures/)
- Seizures of Lennox-Gastaut syndrome in children, when other treatments fail

## Adverse effects

### Common

- Loss of appetite and weight loss
- Heartburn, vomiting, constipation and diarrhoea
- Difficulty sleeping and nervousness
- Drowsiness

### Serious (rare, important)

- Aplastic anaemia, at a rate that may be more than 100 times that of the general population
- Liver failure
- Suicidal thoughts

## Contraindications

- Hypersensitivity to felbamate or other carbamates
- History of any blood dyscrasia
- Liver dysfunction

## Key interactions

**Phenytoin**
Felbamate raises phenytoin levels

**Valproate**
Felbamate raises valproate levels

**Carbamazepine**
Lower carbamazepine but higher carbamazepine epoxide levels

**Low-dose combined oral contraceptives**
Lower hormone levels

## What is monitored

- Complete blood count before and during treatment
- Liver tests before and during treatment
- Signs of infection, bleeding, jaundice or dark urine
- Mood and suicidal thoughts

## Administration and safety

- Given by mouth as tablets or suspension
- Used only after the patient or guardian has been informed of the risks, with written acknowledgement
- Withdrawn gradually: stopping suddenly can trigger seizures

## Nursing care

- Confirm the risk acknowledgement has been signed before starting
- Teach to report fever, sore throat, bruising, bleeding or yellow skin at once
- Check that blood and liver tests are done on schedule
- Watch appetite and weight

## Pregnancy and breastfeeding

Human data are limited; benefits and risks are weighed with specialist care.

## Memory aid

Felbamate: «Fel-BAD-mate» – works when others fail, but can empty the marrow and fail the liver.

## Test yourself

Think of the answer, then tap the question to see it.

## What are the two boxed warnings of felbamate?

Aplastic anaemia and hepatic failure, which is why it is reserved for severe epilepsy when the benefit justifies the risk.

## At which receptor site does felbamate act?

The strychnine-insensitive glycine site of the NMDA glutamate receptor.

## What does felbamate do to phenytoin and valproate levels?

It raises both, so their doses are often reduced when felbamate is started.

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## Related drugs

- [Clobazam](https://durgical.com/en/pharmacology/clobazam/)

## Related conditions

- [Epilepsy and seizures](https://durgical.com/en/conditions/epilepsy-and-seizures/)

[← Back to the class: Antiseizure medicines](https://durgical.com/en/pharmacology/classes/antiseizure-medicines/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Felbamate: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a606011.html) (MedlinePlus (U.S. National Library of Medicine), 2020); [DailyMed - FELBAMATE tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f2edb3ed-da20-4093-88ea-00fe781e47e0) (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 20 (McGraw Hill, 2023).

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