Primidone, sold under various brand names, is a barbiturate medication that is used to treat partial and generalized seizures, as well as essential tremors. It is taken by mouth.Common side effects include sleepiness, poor coordination, nausea, and loss of appetite. Severe side effects may include suicide, psychosis, a lack of blood cells. Use during pregnancy may result in harm to the baby. Primidone is an anticonvulsant of the barbiturate class. How it works is not entirely clear.Primidone was approved for medical use in the United States in 1954. It is available as a generic medication. In 2017, it was the 238th most commonly prescribed medication in the United States, with more than two million prescriptions. Medical uses
Epilepsy
Licensed for generalized tonic-clonic and complex partial seizures in the United Kingdom. In the United States, primidone is approved for adjunctive (in combination with other drugs) and monotherapy (by itself) use in generalized tonic-clonic seizures, simple partial seizures, and complex partial seizures, and myoclonic seizures. In juvenile myoclonic epilepsy (JME), it is a second-line therapy, reserved for when the valproates or lamotrigine do not work and when other second-line therapies—acetazolamide work either.Open-label case series have suggested that primidone is effective in the treatment of epilepsy. Primidone has been compared to phenytoin, phenobarbital, mephobarbital, ethotoin, metharbital, and mephenytoin. In adult comparison trials, primidone has been found to be just as effective. Essential tremor
Primidone is considered to be a first-line therapy for essential tremor along with propranolol.
This is the only susceptibility factor that is generally agreed upon. Anticonvulsants do not seem to increase the incidence of Dupuytrens contracture in non-whites.Primidone has other cardiovascular effects in beyond shortening the QT interval. Both it and phenobarbital are associated with elevated serum levels (both fasting and six hours after methionine loading) of homocysteine, an amino acid derived from methionine. This is almost certainly related to the low folate levels reported in primidone users. Elevated levels of homocysteine have been linked to coronary heart disease. In 1985, both drugs were also reported to increase serum levels of high density lipoprotein (HDL) cholesterol, total cholesterol, and apolipoproteins A and B.It was first reported to exacerbate hepatic porphyria in 1975. In 1981, it was shown that phenobarbital, one of primidones metabolites, only induced a significant porphyrin at high concentrations in vitro. It can also cause elevations in hepatic enzymes such as gamma-glutamyl transferase and alkaline phosphatase.Less than 1% of primidone users will experience a rash. Compared to carbamazepine, lamotrigine, and phenytoin, this is very low. The rate is comparable to that of felbamate, vigabatrin, and topiramate. Primidone also causes exfoliative dermatitis, Stevens–Johnson syndrome, and toxic epidermal necrolysis. Primidone, along with phenytoin and phenobarbital, is one of the anticonvulsants most heavily associated with bone diseases such as osteoporosis, osteopenia (which can precede osteoporosis), osteomalacia and fractures. The populations usually said to be most at risk are institutionalized people, postmenopausal women, older men, people taking more than one anticonvulsant, and children, who are also at risk of rickets.