Overview
DESCRIPTION Tiagabine hydrochloride USP is an antiepilepsy drug available as 2 mg, 4 mg, 12 mg, and 16 mg tablets for oral administration. Its chemical name is (-)-(R)-1-[4,4-Bis(3-methyl-2-thienyl)-3 butenyl]nipecotic acid hydrochloride, its molecular formula is C 20 H 25 NO 2 S 2 HCl, and its molecular weight is 412.01. Tiagabine HCl, USP is a white to off-white powder.
Mechanism of Action
CLINICAL PHARMACOLOGY Mechanism of Action The precise mechanism by which tiagabine exerts its antiseizure effect is unknown, although it is believed to be related to its ability, documented in in vitro experiments, to enhance the activity of gamma aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. These experiments have shown that tiagabine binds to recognition sites associated with the GABA uptake carrier. It is thought that, by this action, tiagabine blocks GABA uptake into presynaptic neurons, permitting more GABA to be available for receptor binding on the surfaces of post-synaptic cells. Inhibition of GABA uptake has been shown for synaptosomes, neuronal cell cultures, and glial cell cultures.
Indications
- INDICATIONS AND USAGE Tiagabine hydrochloride tablet is indicated as adjunctive therapy in adults and children 12 years and older in the treatment of partial seizures.
Common Doses
- 4 mg
- 8 mg
- 32 mg
- 56 mg
Dosage
DOSAGE AND ADMINISTRATION General: The blood level of tiagabine obtained after a given dose depends on whether the patient also is receiving a drug that induces the metabolism of tiagabine. The presence of an inducer means that the attained blood level will be substantially reduced. Dosing should take the presence of concomitant medications into account. Tiagabine hydrochloride tablet is recommended as adjunctive therapy for the treatment of partial seizures in patients 12 years and older.
Contraindications
- CONTRAINDICATIONS Tiagabine hydrochloride is contraindicated in patients who have demonstrated hypersensitivity to the drug or its ingredients.
Side Effects
- ADVERSE REACTIONS The most commonly observed adverse events in placebo-controlled, parallel-group, add-on epilepsy trials associated with the use of tiagabine hydrochloride in combination with other antiepilepsy drugs not seen at an equivalent frequency among placebo-treated patients were dizziness/light-headedness, asthenia/lack of energy, somnolence, nausea, nervousness/irritability, tremor, abdominal pain, and thinking abnormal/difficulty with concentration or attention.
Interactions
- Drug Interactions In evaluating the potential for interactions among co-administered antiepilepsy drugs (AEDs), whether or not an AED induces or does not induce metabolic enzymes is an important consideration. Carbamazepine, phenytoin, primidone, and phenobarbital are generally classified as enzyme inducers; valproate and gabapentin are not. Tiagabine hydrochloride is considered to be a non-enzyme inducing AED (see PRECAUTIONS, General, Use in Non-Induced Patients ).