What Is Ethosuximide?
Ethosuximide is an antiepileptic drug with the chemical formula C7H11NO2.
Ethosuximide exhibits anticonvulsant properties and has been shown to suppress seizures in preclinical studies with mice.
In Japan, it is marketed as Zarontin Syrup and Epileoptimal Spray 50%. It can be used alone or in combination with other antiepileptic drugs such as sodium valproate.
Uses of Ethosuximide
Ethosuximide is used as a therapeutic agent. Eisai markets Epileoptimal Spray 50%.
Indications include typical absence seizures (minor seizures) and minor (motor) seizures. Ethosuximide is administered orally to adult patients in doses of 450 to 1,000 mg (0.9 g to 2 g of the 50% epileoptimal spray formulation daily) in two to three divided doses per day.
The most common side effects of ethosuximide include SLE-like symptoms, pancytopenia, aplastic anemia, and Stevens-Johnson syndrome.
Properties of Ethosuximide
Ethosuximide is extremely soluble in methanol, ethanol, and N, N-dimethylformamide, and soluble in water. It is an odorless, white, paraffin-like powder with a melting point of 47.0-50.0°C and a boiling point of 265.3°C.
Together with its effects on blocking T-type calcium channels and other classes of ion channels, ethosuximide is thought to affect neuronal excitability. Ethosuximide was discovered to be a blocker of T-type calcium channels.
Subsequent experiments with recombinant T-type channels in cellular systems have demonstrated that ethosuximide blocks all T-type calcium channel isoforms.
Structure of Ethosuximide
Ethosuximide has a molecular weight of 141.17 and a density of 1.1522 g/cm3. It consists of a methyl group and an ethyl group attached to a cyclic imide, succinimide.
Ethosuximide has structural isomers: (S)-ethosuximide and (R)-ethosuximide. A 1:1 mixture of (S)-ethosuximide and (R)-ethosuximide is used in clinical practice.
Other Information on Ethosuximide
1. Ethosuximide Interactions
Ethosuximide’s blood levels are affected by sodium valproate. Its combination with valproate increases the protective index and may elevate the serum concentration of phenytoin compared to monotherapy. Blood levels of Ethosuximide may be reduced by carbamazepine or rufinamide.
2. Side Effects of Ethosuximide
Common side effects include insomnia, somnolence, headache, delirium, and ataxia. Digestive system side effects encompass indigestion, anorexia, nausea, vomiting, tongue swelling, sudden abdominal pain, weight loss, stomach pain, diarrhea, constipation, and gingival hyperplasia.
Adverse skin effects comprise Stevens-Johnson syndrome, systemic lupus erythematosus, hirsutism, urticaria, and pruritic erythematous rash. Possible urinary system effects include microscopic hematuria and genital malaise, while blood-related effects may include pancytopenia, leukopenia, agranulocytosis, and eosinophilia.
3. Compounds Related to Ethosuximide
Other succinimide compounds, such as phensuximide and mesuximide (Methosuximide), can be utilized in pharmaceutical substructures. Succinimide compounds have applications in forming covalent bonds in proteins, peptides, and plastics.