The relationship between vigabatrin dosage and plasma concentrations, platelet GABA-transaminase inhibition and seizure reduction in 16 children with refractory epilepsy was studied at the University of Cantabria, Santander, Spain. Vigabatrin dosages of 57 mg/kg/day and plasma concentrations of 8 mg/L reduced the GABA-T activity from 13.9 to 5.1 and seizures were reduced from 51 to 22 per month. Seizure reduction was correlated with the dosage but not with the plasma concentration or with platelet GABA inhibition. The initial dose of vigabatrin recommended was 50 mg/kg/day and was increased to 75 or 100 mg/kg/day. [1]

COMMENT. A study of vigabatrin in 43 children with intractable epilepsy is reported from the Royal Liverpool Children’s Hospital, England. The results showed that complex partial seizures, with or without secondary generalization, responded best with more than 1/2 achieving a greater than 50% reduction. Generalized tonic-clonic seizures also improved. Absence or myoclonic seizures were not benefited. Only 4 patients (10%) were seizure free on monotherapy with vigabatrin. [2]

In a study of 45 patients ages 2-21 years treated with vigabatrin in Paris, France, 20 (44%) showed no benefit and 24% were well controlled. Partial seizures were most responsive.