Primidone

Primidone, sold under various brand names (including Mysoline), is a barbiturate medication that is used to treat partial and generalized seizures and essential tremors. It is taken by mouth. Its common side effects include sleepiness, poor coordination, nausea, and loss of appetite. Severe side effects may include suicide and psychosis. Use during pregnancy may result in harm to the fetus. Primidone is an anticonvulsant of the barbiturate class; however, its long-term effect in raising the seizure threshold is likely due to its active metabolite, phenobarbital. The drug’s other active metabolite is Phenylethylmalonamide (PEMA). Primidone was approved for medical use in the United States in 1954. It is available as a generic medication. In 2023, it was the 239th most commonly prescribed medication in the United States, with more than 1 million prescriptions.