Home Drug Guide Vigabatrin

Drug Guide

Generic Name

Vigabatrin

Brand Names Sabril, Vigadrone, Vigpoder, Vigafyde

Classification

Therapeutic: Anticonvulsant, Glutamate Antagonist

Pharmacological: GABA Transaminase Inhibitor

FDA Approved Indications

Partial onset seizures in adults and children ≥1 month with epilepsy
Infantile spasms in children aged 1 month and older

Mechanism of Action

Vigabatrin irreversibly inhibits gamma-aminobutyric acid (GABA) transaminase, leading to increased levels of GABA in the brain, which enhances inhibitory neurotransmission and suppresses seizure activity.

Dosage and Administration

Adult: Typically, 1 gram twice daily. Dose adjustments based on response and tolerability.

Pediatric: Starting dose usually 50-100 mg/kg/day divided twice daily, titrated up based on efficacy and tolerability.

Geriatric: Dose adjustment may be necessary; start at lower doses and titrate carefully.

Renal Impairment: Dose reduction is recommended in renal impairment; specific adjustments depend on degree of impairment.

Hepatic Impairment: No specific adjustment; caution advised as data are limited.

Pharmacokinetics

Absorption: Well absorbed orally with peak plasma concentrations in 1-2 hours.

Distribution: Widely distributed; crosses the blood-brain barrier.

Metabolism: Minimal hepatic metabolism; most is excreted unchanged by the kidneys.

Excretion: Primarily excreted unchanged in urine.

Half Life: Approximately 26 hours, allowing for twice daily dosing.

Contraindications

Hypersensitivity to vigabatrin or its components

Precautions

History of psychosis or depression; risk of visual field loss; monitor mental health; cautious use in renal impairment.

Adverse Reactions - Common

Somnolence (Common)
Dizziness (Common)
Fatigue (Common)

Adverse Reactions - Serious

Visual field constriction (Serious (can be permanent))
Psychiatric effects (depression, psychosis) (Serious)
Peripheral vision loss (Serious)

Drug-Drug Interactions

Other CNS depressants (additive sedative effects)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Baseline visual fields, mental health status, renal function.

Diagnoses:

Risk for visual impairment related to visual field constriction.
Risk for depression or psychiatric disturbance.

Implementation: Monitor visual fields regularly (e.g., every 3 months).

Evaluation: Assess for visual changes, mental health status, and seizure control.

Patient/Family Teaching

Report new visual disturbances immediately.
Do not stop medication abruptly.
Avoid driving or operating machinery if visual changes occur.
Discuss mental health status regularly.

Special Considerations

Black Box Warnings:

Persistent vision loss due to bilateral visual field constriction.
Potential for severe mental health disturbances, including psychosis and depression.

Genetic Factors: Genetic testing is not routinely required but consider in patients with family history.

Lab Test Interference: No known interference.

Overdose Management

Signs/Symptoms: Excessive sedation, hypotension, coma (rare).

Treatment: Supportive care; no specific antidote. Hemodialysis may be considered in severe cases to enhance elimination.

Storage and Handling

Storage: Store at room temperature, away from moisture and heat.

Stability: Stable for the duration of the expiry date provided.