Vigabatrin

Drug class: Anticonvulsant

Vigabatrin (SABRIL)（中文：氯己烯酸）

Common Strengths of Vigabatrin

Vigabatrin are available in the following strengths:

• Tablet: 500 mg

Drug Trade Names of Vigabatrin

Sabril

Drug Usage

Vigabatrin is used for:

• Treatment of refractory complex partial seizures in adults and children aged 2 years and older.
• Treatment of infantile spasms in infants aged 1 month to 2 years.

Mechanism of Action

Vigabatrin works by irreversibly inhibiting GABA transaminase, the enzyme responsible for the breakdown of GABA (gamma-aminobutyric acid). This increases the levels of GABA in the brain, which helps stabilize electrical activity and reduce seizures.

Route of Administration

Oral

Dosages

• Adults:
  • Complex Partial Seizures: Start with 500 mg orally every 12 hours, increasing by 500 mg increments weekly to a target dose of 1.5 g every 12 hours.

• Children:
  • Infantile Spasms: Initial dose of 50 mg/kg/day, divided into two doses, with increments every 3 days to a maximum of 150 mg/kg/day.

• Renal Impairment:
  • Mild (CrCl >50 to 80 mL/min): Decrease dose by 25%.
  • Moderate (CrCl >30 to 50 mL/min): Decrease dose by 50%.
  • Severe (CrCl >10 to 30 mL/min): Decrease dose by 75%.

Side Effects

Frequency	Adverse reactions
Common Side Effects	Headache
	Somnolence (Sleepiness)
	Fatigue
	Dizziness
	Weight gain
	Tremor
	Visual field defects
Serious Side Effects	The most serious and concerning side effects of vigabatrin is permanent vision loss, including bilateral concentric visual field constriction and decreased visual acuity. This risk increases with higher doses and longer exposure to the drug there is no know safe dose or exposure duration that is free from this risk.
Other Serious side effects	Psychiatric symptoms like psychosis, depression, and suicidal ideation
	Respiratory depression, especially in overdose
	Peripheral neuropathy
	Edema
	Severe allergic reactions

Pharmacokinetics

• Absorption: Vigabatrin is rapidly absorbed; peak plasma concentrations occur approximately 1 hour after administration.
• Half-Life: About 5 to 8 hours.
• Metabolism: Not significantly metabolized; primarily eliminated unchanged.
• Excretion: Primarily through renal excretion; about 95% of the drug is excreted in urine.

Drug Precautions

Pregnancy

Potential risks to the fetus.

Breastfeeding

Excreted in breast milk; caution is advised.

Children and Elderly

Safety and efficacy established in children; elderly patients may require careful monitoring.

Monitoring Requirements

Monitor vision periodically, liver function, and signs of mood changes.

Drug Interactions

Vigabatrin can interact with other medications that affect GABA levels and may increase the risk of CNS depression.

FAQ

How Should I Take the Tablet?

Take exactly as prescribed, usually with or without food.

What Should I Avoid While Taking?

Avoid alcohol and other CNS depressants; be cautions when driving or operating machinery until you know how vigabatrin affect you.

What Happens if I Miss a Dose?

Take the missed dose as soon as you remember, but skip it if it is close to the next dose. Do not double up.