tiagabine hydrochloride

Action

Unknown. Thought to raise seizure threshold by enhancing activity of gamma-aminobutyric acid (a major inhibitory neurotransmitter in CNS).

Availability

Tablets: 2 mg, 4 mg, 12 mg, 16 mg, 20 mg

Indications and dosages

➣ Adjunctive treatment of partial seizures

Adults older than age 18: Initially, 4 mg P.O. once daily for 1 week; may increase as needed by 4 to 8 mg/day at weekly intervals, up to 56 mg/day in two to four divided doses

Adolescents ages 12 to 18: Initially, 4 mg P.O. once daily. May increase total daily dosage by 4 mg at start of week 2; thereafter, may increase by 4 to 8 mg q week until clinical response occurs or patient is receiving up to 32 mg/day. Give total daily dosage in two to four divided doses.

Dosage adjustment

• Hepatic impairment

Off-label uses

• Anxiety

Contraindications

• Hypersensitivity to drug or its components

Precautions

Use cautiously in:

• hepatic impairment

• pregnant or breastfeeding patients

• children younger than age 12 (safety not established).

Administration

Don't stop drug suddenly. Dosage must be tapered.

• Be aware that concomitant anticonvulsant therapy need not be modified unless indicated.

Adverse reactions

CNS: dizziness, insomnia, drowsiness, nervousness, asthenia, confusion, poor concentration, impaired memory, depression, emotional lability, hostility, agitation, ataxia, abnormal gait, tremors, paresthesia, speech disorder, language problems

CV: vasodilation

EENT: nystagmus, epistaxis, pharyngitis

GI: nausea, vomiting, diarrhea, abdominal pain, mouth ulcers

Musculoskeletal: myasthenia

Respiratory: increased cough

Skin: rash, pruritus

Other: increased appetite, weight changes, pain, allergic reaction

Interactions

Drug-drug. Carbamazepine, phenobarbital, phenytoin, primidone: increased tiagabine clearance, decreased blood level

Patient monitoring

Watch for signs or symptoms of depression and suicidal ideation.

• Assess vital signs and cardiovascular status.

• Monitor closely for severe generalized weakness. If present, consult prescriber regarding possible dosage reduction.

Patient teaching

• Tell patient to take on regular schedule with food.

Caution patient not to stop therapy suddenly. Dosage must be tapered.

• Instruct patient to report signs or symptoms of depression.

Advise patient to report neurologic reactions. Tell him to contact prescriber immediately if severe overall weakness or severe depression occurs.

• Advise female patient to tell prescriber if she suspects she is pregnant.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs mentioned above.