Kigabeq (Vigabatrin)

Vigabatrin acts on the GABAergic pathway to reduce seizure activity in specific epilepsy syndromes.

• Refractory complex partial seizures: reduces seizure frequency in patients whose seizures are not controlled by other antiepileptic drugs.
• Infantile spasms (West syndrome): helps control spasms and improve EEG patterns in infants with this severe epilepsy.
• Adjunctive therapy in focal epilepsy: used as an add‑on when monotherapy fails to achieve adequate seizure control.

• Vigabatrin irreversibly inhibits the enzyme GABA transaminase, the primary catabolic pathway for the inhibitory neurotransmitter gamma‑aminobutyric acid (GABA). By blocking this enzyme, cerebral GABA concentrations rise, enhancing inhibitory neurotransmission and stabilizing neuronal excitability, which contributes to seizure suppression in epilepsy.

Vigabatrin may be associated with several adverse reactions that vary in frequency and severity.

Common Side Effects

• Fatigue: persistent tiredness or lack of energy.
• Dizziness: sensation of light‑headedness or unsteadiness.
• Nausea: feeling of stomach upset, sometimes with vomiting.
• Headache: mild to moderate cranial pain.
• Somnolence: increased sleepiness during the day.

Serious or Rare Side Effects

• Visual field defects: loss of peripheral vision that may be irreversible.
• Depression or suicidal thoughts: mood changes requiring immediate medical attention.
• Severe skin reactions: such as Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Anaphylaxis: rare systemic allergic reaction with breathing difficulty.

Before initiating Vigabatrin therapy, several precautionary measures should be considered to ensure patient safety.

• Visual field monitoring: obtain baseline visual field testing and repeat periodically during treatment.
• Pregnancy and lactation: avoid use unless benefits outweigh potential risks; discuss with obstetric specialist.
• Renal function: assess renal clearance and adjust use in patients with impaired kidney function.
• Concomitant CNS depressants: use cautiously as combined effects may increase sedation.
• Discontinue if serious adverse reactions occur: stop therapy promptly if visual field loss or severe mood changes develop.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture and light.

Vigabatrin can interact with other medicines, altering its efficacy or increasing the risk of adverse effects.

Major Interactions (Avoid)

• Combined use with other GABAergic agents (e.g., benzodiazepines, barbiturates): may enhance central nervous system depression.
• Co‑administration with drugs that lower seizure threshold (e.g., tramadol, bupropion): may reduce overall seizure control.

Moderate Interactions (Monitor Closely)

• CYP450 enzyme inducers (e.g., carbamazepine, phenytoin): may decrease vigabatrin plasma levels, requiring efficacy monitoring.
• Anticoagulants (e.g., warfarin): may require INR monitoring due to potential pharmacodynamic changes.
• Antihistamines or anticholinergics: may increase sedation; observe patient response.