Ethosuximide, sold under the brand name Zarontin among others, is a medication used to treat absence seizures. It may be used by itself or with other antiseizure medications such as valproic acid. Ethosuximide is taken by mouth.Ethosuximide is usually well tolerated. Common side effects include loss of appetite, abdominal pain, diarrhea, and feeling tired. Serious side effects include suicidal thoughts, low blood cell levels, and lupus erythematosus. It is unclear if it is safe for the baby during pregnancy. Ethosuximide is in the succinimide family of medications. Its mechanism of action is thought to be due to antagonism of the postsynaptic T-type voltage-gated calcium channel.Ethosuximide was approved for medical use in the United States in 1960. It is on the World Health Organizations List of Essential Medicines. Ethosuximide is available as a generic medication. As of 2019 its availability was limited in many countries with concerns of price fixing in the United States. Medical uses
It is approved for absence seizures. Ethosuximide is considered the first choice drug for treating absence seizures in part because it lacks the idiosyncratic hepatotoxicity of the alternative anti-absence drug, valproic acid. Adverse effects
As with other anticonvulsants, ethosuximide carries a warning about use during pregnancy. Although a causal relationship with birth defects has not be established, the potential for harm to the baby is weighed against the known harm caused by a mother having even minor seizures.
The next year, they showed that anticonvulsant succinimides did this and that the pro-convulsant ones did not. The first part was supported by Kostyuk et al. in 1992, who reported a substantial reduction in current in dorsal root ganglia at concentrations ranging from 7 μmol/L to 1 mmol/L.That same year, however, Herrington and Lingle found no such effect at concentrations of up to 2.5 mmol/L. The year after, a study conducted on human neocortical cells removed during surgery for intractable epilepsy, the first to use human tissue, found that ethosuximide had no effect on Ca2+ currents at the concentrations typically needed for a therapeutic effect.In 1998, Slobodan M. Todorovic and Christopher J. Lingle of Washington University reported a 100% block of T-type current in dorsal root ganglia at 23.7 ± 0.5 mmol/L, far higher than Kostyuk reported. That same year, Leresche et al. reported that ethosuximide had no effect on T-type currents, but did decrease noninactivating Na+ current by 60% and the Ca2+-activated K+ currents by 39.1 ± 6.4% in rat and cat thalamocortical cells. It was concluded that the decrease in Na+ current is responsible for the anti-absence properties.In the introduction of a paper published in 2001, Dr. Juan Carlos Gomora and colleagues at the University of Virginia in Charlottesville pointed out that past studies were often done in isolated neurons that had lost most of their T-type channels.