Mesantoin, also known as phenytoin, is an anticonvulsant medication used to treat epileptic seizures. There are several synonyms for mesantoin, including hydantoin, diphenylhydantoin, and 5,5-diphenyl-2,4-imidazolidinedione. These synonyms can be useful for patients and medical professionals alike, helping to identify the medication and prevent confusion with similar-sounding drugs. Phenytoin is commonly prescribed for long-term management of epilepsy, and may also be used to prevent seizures during neurosurgery or in the treatment of nerve pain. Despite its efficacy, this medication has been associated with several side effects and drug interactions, making careful dosing and monitoring essential.