Pharmacology · Antiseizure medicines
Tiagabine !
An add-on medicine for focal seizures that blocks the GABA transporter GAT-1, so GABA stays longer in the synapse.
Updated 2026-11-01
The figure shows tiagabine bound to the human GABA transporter GAT-1 in its inward-open state.
Mechanism of action
Tiagabine blocks GAT-1, the transporter that takes GABA back into neurons and glia after release. GABA stays longer in the synaptic cleft and inhibits neurons more strongly.
- Binds the GABA transporter GAT-1
- GABA reuptake into neurons and glia is blocked
- GABA stays longer in the synapse
- Inhibition is stronger and seizures less frequent
Pharmacokinetics
- Absorption
- Well absorbed by mouth; food slows absorption but not the amount
- Distribution
- Highly bound to plasma proteins
- Metabolism
- In the liver, mainly by CYP3A
- Half-life
- About 7 to 9 hours; about 2 to 5 hours with enzyme-inducing antiseizure medicines
Indications
- Add-on treatment of focal seizures in adults and adolescents Epilepsy and seizures →
Adverse effects
Common
- Dizziness and lack of energy
- Sleepiness
- Nausea and abdominal pain
- Nervousness, irritability and tremor
- Difficulty concentrating
Contraindications
- Hypersensitivity to tiagabine
Key interactions
- Enzyme-inducing antiseizure medicines (carbamazepine, phenytoin, phenobarbital)
- Much faster clearance and lower tiagabine levels
- Other highly protein-bound drugs
- Possible displacement
- Alcohol and other sedatives
- More sleepiness and dizziness
What is monitored
- Seizure control and any new seizure type
- Dizziness and concentration
- Mood and suicidal thoughts
Administration and safety
- Given by mouth
- Not used outside epilepsy: in people without epilepsy it has caused seizures
- Withdrawn gradually
Nursing care
- Check whether the patient also takes enzyme inducers, which change its effect
- Warn about dizziness and sleepiness before driving
- Teach to report new or different seizures
Pregnancy and breastfeeding
Human data are limited; benefits and risks are weighed with specialist care.
Test yourself
Think of the answer, then tap the question to see it.
What is the target of tiagabine?
GAT-1, the GABA transporter that takes GABA back into neurons and glia.
Why can tiagabine be dangerous in people without epilepsy?
Off-label use has been linked to new seizures and status epilepticus in people without epilepsy.
How do enzyme inducers change tiagabine?
Carbamazepine, phenytoin and phenobarbital speed its clearance and shorten its half-life.
Related drugs
Related conditions
← Back to the class: 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: Tiagabine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - TIAGABINE HYDROCHLORIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.