Tiagabine (Gabitril, Abbott and Novo-Nordisk)
Tiagabine is a "designer drug" formulated to block inactivation (uptake) of the brain's main inhibitory neurotransmitter, GABA. When more GABA accumulates in the brain, seizures are harder to initiate and sustain. Gabitril is useful for partial and secondarily generalized seizures. It is not effective for absence or myoclonic seizures.
The side effect profile is acceptable, with some sedation, abnormal thinking, and dizziness. Scattered reports have detailed paradoxical worsening of seizures from tiagabine, and a few serious psychiatric complications. Tiagabine has a short half-life, but has been documented to be effective on a twice-daily basis.
Summary Data for Tiagabine
Pill sizes:
2 mg tablet
4 mg (yellow tablet, not scored)
12 mg (green tablet, not scored)
16 mg (blue tablet, not scored)
20 mg (pink tablet, not scored)
Liquid for oral: none.
Injectable: none.
Typical adult dose: Begin with 4 mg at bedtime for a week, then increase 4 mg each week to 16 - 56 mg/d in two divided doses.
Typical pediatric dose: 4-32 mg/d in 2 - 4 divided doses.
Metabolism: liver metabolism by the CYP 3A4 system.
Half-life: 4 - 10 hours.
Serum levels: not established.
Pregnancy: Category C - can cause birth defects in animals, unknown in humans.
Drugs that lower TGB levels: Dilantin, phenobarbital, Tegretol.
Dangerous Side Effects
Rare induction of nonconvulsive status epilepticus (prolonged confusional seizures); rare psychosis or hallucinations.
Common Side Effects
Sleepiness, dizziness, imbalance, thinking difficulty, stomach upset.
Other Side Effects
Personality change, tremor.