Vigabatrin in the Treatment of Infantile Spasms
Vigabatrin in the Treatment of Infantile Spasms
US Neurology, 2010;5(2):82-4
Abstract
Vigabatrin (VGB) is an effective treatment of infantile spasms (IS) that controls spasms of all etiologies in about 50% of patients when used as monotherapy. In tuberous sclerosis complex, VGB controls spasms in up to 95% of patients and should be used as the drug of choice. Higher VGB doses correlate with shorter times to response and higher response rates. Its most serious side effect is retinal toxicity characterized by irreversible bilateral concentric constriction of the visual fields (BCCVF). Maximum VGB dose, total VGB dose, and duration of VGB treatment constitute risk factors for BCCVF. In each particular patient, dose and duration of treatment should be kept at a minimum, while ensuring effectiveness and preventing relapse. Every effort should be made to evaluate retinal function, even though it may require specialized ophthalmological services. The addition of this new US Food and Drug Administration (FDA)-approved drug as an alternative in the treatment of IS represents a major contribution to an armamentarium that contains only one other treatment.
Keywords
Vigabatrin, tuberous sclerosis complex, infantile spasms, visual field constriction, children, side effect
Disclosure: The authors have no conflicts of interest to declare.
Received: April 22, 2009 Accepted: October 20, 2009
Correspondence: Susana E Camposano, MD, Herscot Center for Tuberous Sclerosis Complex, Neurology Department, Massachusetts General Hospital, 175 Cambridge Street, Suite 340, Boston, MA 02114. E: scamposano@partners.org
Vigabatrin in Infantile Spasms
Vigabatrin (VGB) was only recently approved by the US Food and Drug Administration (FDA) as monotherapy for infantile spasms (IS). Nonetheless, considerable experience is available, since VGB has been used for more than 10 years in other countries. The delay in approval in the US relates in part to its safety profile, since it can cause irreversible retinal toxicity.
VGB is an irreversible inhibitor of gamma-aminobutyric acid transaminase (GABA-T), which has a favorable pharmacokinetic profile since it is not metabolized by the liver, is excreted by the kidney, has low protein binding, and has a long effective half-life, allowing once- or twice-daily dosing. Interaction with other antiepileptic drugs is minimal.1
Ample evidence has been provided to support the use of VGB in the treatment of IS, and for many years European neurologists have considered VGB to be the drug of choice for the symptomatic treatment of IS.2–4 Used as a first line of treatment in monotherapy, the percentage of children who are rendered seizure-free averages around 50%.5–10 Efficacy is lower in refractory cases, but still approaches total control in 30% of children.11,12 Tuberous sclerosis complex (TSC) represents a particularly successful story for the use of VGB, since the drug controls spasms in up to 95% of patients.10,11,13
When VGB is compared with hormonal (corticosteroid) treatment for IS, the response to hormonal treatment is faster and initially benefits a higher percentage of patients. However, assessed again at 14 months of age, patients exhibit comparable response rates as a result of fewer subsequent relapses following VGB use.7,14 Early studies had suggested that symptomatic IS respond better to VGB than idiopathicIS,15 particularly IS resulting from cerebral malformations.16 These results have not been replicated in the more recent studies.
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Vigabatrin, tuberous sclerosis complex, infantile spasms, visual field constriction, children, side effect, epilepsy symptoms, epilepsy treatment, epilepsy drugs, tuberous sclerosis complex diagnosis, tuberous sclerosis complex 1 protein, tuberous sclerosis complex complication, tuberous sclerosis complex genetics, Vigabatrin tuberous sclerosis,
