Tiagabine Hydrochloride

(TIE-egg-un-bine)

  Action:
Mechanism unknown; may block GABA uptake into presynaptic neurons, allowing more GABA to be available for binding with the GABA receptor of post-synaptic cells.

  Indications:
Adjunctive treatment in treatment of partial seizures.

  Contraindications:
Standard considerations.

  Route/Dosage:

Adolescents 12 to 18 yr:
PO Initial dose 4 mg qd. Increase dose by 4 mg after 1 week and thereafter by 4 to 8 mg at weekly intervals until response achieved or total of 32 mg/day.

Adults:
PO Initial dose 4 mg qd. Increase by 4 to 8 mg at weekly intervals until response achieved or total of 56 mg/day.

  Interactions:

Enzyme-inducing antiepileptic drugs (eg, carbamazepine, phenytoin, primidone, phenobarbital): Increased tiagabine clearance.

  Lab Test Interferences:
None well documented.

  Adverse Reactions:

CNS:

Dizziness; lightheadedness; somnolence; nervousness; irritability; agitation; hostility; language problem; tremor; abnormal gait; ataxia; abnormal thinking; concentration/attention difficulty; depression; confusion; insomnia; speech disorder; difficulty with memory; paresthesia; emotional lability.

DERM:

Rash; pruritus; occhymosis.

EENT:

Nystagmus; amblyopia; pharyngitis.

GI:

Nausea; abdominal pain; diarrhea; vomiting; increased appetite; mouth ulceration; gingivitis.

OTHER:

Asthenia; lack of energy; pain; cough; myasthenia; accidental injury; infection; flu syndrome; myalgia; urinary tract infection; vasodilation.

  Precautions:

Pregnancy: Category C.

Lactation: Undetermined.

Children: Safety and efficacy in children < 12 yr not established.

Hepatic function impairment: Dosage reduction or longer dosing interval may be necessary.

Serious adverse effects: During clinical trials some patients experienced status epilepticus, and 10 sudden unexplained deaths occurred. The association of these events with tiagabine use is unclear.

Withdrawal: Do not discontinue antiepileptic drugs abruptly because of possible increased seizure frequency on drug withdrawal.

EEG: Patients with a history of spike and wave discharges on EEG may have exacerbations of EEG abnormalities associated with cognitive/neuropsychiatric events, which may be a manifestation of underlying seizure activity. Dosage reduction of tiagabine may be necessary.

  Administration/Storage:

• Administer medication with food.
• Titrate dose at weekly intervals to effective or maximum dose.
• Administer initial dose as single daily dose. The total daily dose should be given as equally divided doses 2 to 4 times a day.
• Discontinue medication gradually over minimum of 1 wk.
• Store at room temperature, protected from light and moisture.

  Assessment/Interventions:

• Obtain patient history, including drug history and any known allergies. Note hepatic function impairment and seizure pattern.
• Assess baseline vital signs.
• Assess for development of side effects. Notify health care provider if noted.
• Withdraw medication gradually to avoid the possibility of increasing seizure frequency.

  Patient/Family Education:

• Advise patient that medication should be taken with food.
• Explain that missed dose should be taken as soon as possible but that 2 doses should not be taken together. Instruct patient to call health care provider if 2 doses are missed.
• Instruct patient to report these symptoms to health care provider: somnolence, excessive fatigue or weakness, dizziness, concentration or attention difficulty, difficulty with memory, speech disorder, ataxia.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
• Advise patient to use caution when taking these other drugs with CNS depressant effects (eg, alcohol, sedatives).
• Advise patient to notify their health care provider if they become pregnant, plan on becoming pregnant, or are breastfeeding while taking this medication.

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