Primidone is an anticonvulsant drug that is structurally related to phenobarbital. Primidone is metabolized to phenobarbital and therefore shares its anticonvulsant and sedative properties.
Primidone is effective in all types of seizure disorders except absence seizures.
Primidone may be used alone, in sub-hypnotic doses, or in combination with other anticonvulsants. Primidone was introduced as an anticonvulsant in 1952, and it was approved by the FDA in 1954. Like phenobarbital, primidone raises the seizure threshold and inhibits spread from a seizure focus. PEMA is the major metabolite and is a less potent anticonvulsant than phenobarbital, but it may potentiate the effects of phenobarbital. PEMA is more toxic than primidone.