Names and pronunciation
(tie-ah-ga′been) Gabitril
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Drug reference
(tie-ah-ga′been) Gabitril
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Func. class.: Anticonvulsant
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Do not confuse: tiaGABine/tiZANidine
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ACTION: Inhibits reuptake and metabolism of GABA, may increase seizure threshold; structurally similar to GABA; tiaGABine binding sites in neocortex, hippocampus
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USES: Adjunct treatment of partial seizures in adults and children ≥12 yr
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CONTRAINDICATIONS: Hyper- sensitivity Precautions: Pregnancy, breastfeeding, children <12 yr, geriatric patients, renal/ hepatic disease, suicidal thoughts/behav- iors, status epilepticus, mania, bipolar disorder, abrupt discontinuation, depression
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SIDE EFFECTS CNS: Dizziness, anxiety, somnolence, ataxia, confusion, asthenia, unsteady gait, depression, suicidal ideation, seizures, tremors, hostility, EEG changes, insomnia CV: Vasodilation, tachycardia, hypertension ENDO: Goiter, hypothyroidism GI: Nausea, vomiting, diarrhea, increased appetite INTEG: Pruritus, rash, Stevens-Johnson syndrome, alopecia, hyperhidrosis MS: Myalgia RESP: Pharyngitis, coughing
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INTERACTIONS • Lower doses may be needed when used with valproate Increase: CNS depression—CNS depres- sants, alcohol Decrease: tiaGABine effect—sevelamer Decrease: effect—carBAMazepine, PHE- Nobarbital, phenytoin, primidone Drug/Food Decrease: rate of absorption—high-fat meal
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DOSAGE AND ROUTES • Adult (those receiving an enzyme- inducing antiepileptic product): PO 4 mg/day in divided doses, may increase by 4-8 mg/wk until desired response, max 56 mg/day • Child 12-18 yr: PO 4 mg/day, may in- crease by 4 mg at beginning of wk 2; may increase by 4-8 mg/wk until desired re- sponse; max 32 mg/day Hepatic dose • Adult: PO reduce dose or increase dosing interval
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Available forms: Tabs 2, 4, 12, 16 mg
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Administer: • Store at room temperature, away from heat and light • Use with food
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Assess: • Hepatic studies: ALT, AST, bilirubin at baseline and periodically • Seizures: location, duration, presence of aura; assess for weakness • Withdraw gradually to prevent seizures • May cause status epilepticus and un explained death • Mental status: mood, sensorium, af fect, behavioral changes, suicidal thoughts/ T behaviors; if mental status changes, notify prescriber, hypomania may be present be fore suicide attempt • Assistance with ambulation during early part of treatment; dizziness occurs • Seizure precautions: padded side rails; move objects that may harm patient • Pregnancy/breastfeeding: use only if benefits outweigh fetal risks, may be fetal toxic; pregnant women should enroll in the North American Antiepileptic Drug Pregnancy Registry at 1-888-233-2334; avoid breastfeeding, likely to be excreted in breast milk • Beers: avoid in older adults unless safer alternatives are unavailable; may cause ataxia, impaired psychomotor function
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Evaluate: • Therapeutic response: decreased sei- zure activity; document on patient’s chart
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • To carry emergency ID stating patient’s name, products taken, condition, pre- scriber’s name and phone number • To avoid driving, other activities that require alertness, until response is known • Not to discontinue medication quickly after long-term use • To take with food • To notify prescriber if pregnancy is planned or suspected; to avoid breast feeding • To report suicidal thoughts, behaviors immediately HIGH ALERT
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PHARMACOKINETICS Absorption >95%; peak 45 min; protein binding 96%; metabolized in the liver via CYP3A4; half-life 7-9 hr without enzyme inducers, 2-5 hr with enzyme inducers
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• Child 12-18 yr: PO 4 mg/day, may in- crease by 4 mg at beginning of wk 2; may increase by 4-8 mg/wk until desired re- sponse; max 32 mg/day Hepatic dose
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