This may be due to a decrease in methionine levels, according to a study published in March 2001. In 2005, a study conducted at the University of Catania was published stating that rats whose mothers had consumed 250–1000 mg/kg/day had poorer performance in the water maze and open-field tasks, rats in the 750-mg group were underweight at birth and did not catch up to the control group, and rats in the 1000 mg group did not survive pregnancy.There is no controlled teratology data in humans to date. Sensory
In 2003, vigabatrin was shown by Frisén and Malmgren to cause irreversible diffuse atrophy of the retinal nerve fiber layer in a retrospective study of 25 patients. This has the most effect on the outer area (as opposed to the macular, or central area) of the retina. Visual field defects had been reported as early as 1997 by Tom Eke and others, in the UK. Some authors, including Comaish et al. believe that visual field loss and electrophysiological changes may be demonstrable in up to 50% of Vigabatrin users. The retinal toxicity of vigabatrin can be attributed to a taurine depletion.Due to safety issues, the Vigabatrin REMS Program is required by the FDA to ensure informed decisions before initiating and to ensure appropriate use of this drug.
Others
Vigabatrin reduced cholecystokinin tetrapeptide-induced symptoms of panic disorder, in addition to elevated cortisol and ACTH levels, in healthy volunteers.Vigabatrin is also used to treat seizures in succinic semialdehyde dehydrogenase deficiency (SSADHD), which is an inborn GABA metabolism defect that causes intellectual disability, hypotonia, seizures, speech disturbance, and ataxia through the accumulation of γ-Hydroxybutyric acid (GHB). Vigabatrin helps lower GHB levels through GABA transaminase inhibition. However, this is in the brain only; it has no effect on peripheral GABA transaminase, so the GHB keeps building up and eventually reaches the brain. Adverse effects
Central nervous system
Sleepiness (12.5%), headache (3.8%), dizziness (3.8%), nervousness (2.7%), depression (2.5%), memory disturbances (2.3%), diplopia (2.2%), aggression (2.0%), ataxia (1.9%), vertigo (1.9%), hyperactivity (1.8%), vision loss (1.6%) (See below), confusion (1.4%), insomnia (1.3%), impaired concentration (1.2%), personality issues (1.1%). Out of 299 children, 33 (11%) became hyperactive.Some patients develop psychosis during the course of vigabatrin therapy, which is more common in adults than in children. This can happen even in patients with no prior history of psychosis. Other rare CNS side effects include anxiety, emotional lability, irritability, tremor, abnormal gait, and speech disorder. Gastrointestinal
Abdominal pain (1.6%), constipation (1.4%), vomiting (1.4%), and nausea (1.4%). Dyspepsia and increased appetite occurred in less than 1% of subjects in clinical trials. Body as a whole
Fatigue (9.2%), weight gain (5.0%), asthenia (1.1%). Teratogenicity
A teratology study conducted in rabbits found that a dose of 150 mg/kg/day caused cleft palate in 2% of pups and a dose of 200 mg/kg/day caused it in 9%.