Dosing and uses of Gabitril (tiagabine)
Dosing Forms & Strength
tablet
- 2mg
- 4mg
- 12mg
- 16mg
Partial Seizures (With Hepatic Enzyme-Inducing Anticonvulsants)
Initial: 4 mg/day PO for 1Week
Titrate weekly by 4-8 mg, not to exceed 56 mg/day divided q8-12hr
Partial Seizures (Without Hepatic Enzyme-Inducing Anticonvulsants)
12-22 mg/day PO divided q8-12hr
Other Information
Take with food
Monitor seizure frequency, CBC, renal funtion tests, liver function tests
Pediatric dosage forms and strengths
Dosing Forms & Strength
tablet
- 2mg
- 4mg
- 12mg
- 16mg
Partial Seizures (With Hepatic Enzyme-Inducing Anticonvulsants)
<12 years
- Not established
>12 years
- Initial: 4 mg/day PO for one Week, THEN
- 4 mg PO q12hr for one Week
- Titrate weekly by 4-8 mg, not to exceed 32 mg/day divided q6-12hr
Partial Seizures (Without Hepatic Enzyme-Inducing Anticonvulsants)
<12 years: Not established
>12 years old: same as adult
Other Information
<12 years old: not recommended
Take with food
Geriatric dosage forms and strengths
Partial seizures (with hepatic enzyme-inducing anticonvulsants)
Initial: 4 mg/day PO for 1Week
Titrate weekly by 4-8 mg, not to exceed 56 mg/day divided q8-12hr
Partial seizures (without hepatic enzyme-inducing anticonvulsants)
12-22 mg/day PO divided q8-12hr
Gabitril (tiagabine) adverse (side) effects
>10%
Dizziness (26-30%)
Asthenia (16-20%)
Somnolence (16-20%)
Nausea (11-15%)
1-10%
Abdominal pain (6-10%)
Diarrhea (6-10%)
Vomiting (6-10%)
Nervousness (6-10%)
Pharyngitis (6-10%)
Tremor (6-10%)
Insomnia (6-10%)
Rash (1-5%)
Pruritis (1-5%)
Ataxia (1-5%)
Confusion (1-5%)
Speech d/o (1-5%)
Paresthesia (1-5%)
Depr'n (1-5%)
Pain (1-5%)
Increased appetite (1-5%)
Hostility (1-5%)
Nystagmus (1-5%)
Postmarketing Reports
Bullous dermatitis
Vision blurred
Warnings
Contraindications
Hypersensitivity
Cautions
Antiepileptic drugs (AED) increase risk of suicidal thoughts or behavior in patients taking them for any indication; patients treated with any AED for any indication should be monitored for emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior
Risk of seizures if used in patients without epilepsy (when used off-label in psychiatric disorder); in nonepileptic patients who develop seizures while on therapy, discontinue therapy and evaluate patients for underlying seizure disorder
Should not be abruptly discontinued because of possibility of increasing seizure frequency
Use without enzyme-inducing antiepileptic drugs results in about twice the blood levels than what dosage recommendations are based on
Because clearance of tiagabine is reduced in patients with liver disease, dosage reduction may be necessary in these patients
Adverse events most often associated with therapy were related to central nervous system; the most significant of these can be classified into 2 general categories: 1) impaired concentration, speech or language problems, and confusion (effects on thought processes); and 2) somnolence and fatigue (effects on level of consciousness)
Moderately severe to incapacitating generalized weakness reported; resolves after reduction in dose or discontinuation of thearpy
Pregnancy and lactation
Pregnancy category: C
Lactation: Unknown; use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Gabitril (tiagabine)
Mechanism of action
Blocks reuptake of gamma aminobutyric acid (GABA) by presynaptic neuron thereby enhancing its neurotransmitter inhibitory activity in the nervous system
Pharmacokinetics
Bioavailability: 90%
Peak Plasma Time: 45 min
Protein Bound: 96%
Hepatic cytochrome P450 enzymes, mainly CYP3A4
Metabolites: Inactive
Half-Life: 7-9 hr; (with concomitant CYP3A4 inducers): 4-7 hr
Total Body Clearance: 109 mL/min
Excretion: Feces 63%; urine 25%
