Primidone

Primidone, sold under various brand names, is a medication used to treat seizures including partial and generalized seizures. It may also be used for essential tremors. The dose may be based on levels measured in the blood. It is taken by mouth. Primidone, sold under various brand names, is a medication used to treat seizures including partial and generalized seizures. It may also be used for essential tremors. The dose may be based on levels measured in the blood. 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. A month supply in the United Kingdom costs the NHS about 68.40 £ as of 2019. In the United States the wholesale cost of this amount is about US$13.20. In 2016 it was the 237th most prescribed medication in the United States with more than 2 million prescriptions. 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. Primidone is considered to be a first-line therapy for essential tremor along with propranolol. In terms of tremor amplitude reduction, it is just as effective as propranolol, reducing it by 50%. Both drugs are well studied for this condition, unlike other therapies, and are recommended for initial treatment. 25 mg/day (low-dose therapy) is just as good as 75 mg/day (high-dose therapy). Primidone is not the only anticonvulsant used for essential tremor; the others include topiramate and gabapentin. Other pharmacological agents include alprazolam, clonazepam, atenolol, sotalol, nadolol, clozapine, nimodipine, and botilinum toxin A. Many of these drugs were less effective (according to Table 1), but a few were not. Only propranolol has been compared to primidone in a clinical trial. In 1965, Monroe and Wise reported using primidone along with a phenothiazine derivative antipsychotic and chlordiazepoxide in treatment-resistant psychosis. What is known is that ten years later, Monroe went on to publish the results of a meta-analysis of two controlled clinical trials on people displaying out-of-character and situationally inappropriate aggression, who had abnormal EEG readings, and who responded poorly to antipsychotics; one of the studies was specifically mentioned as involving psychosis patients. When they were given various anticonvulsants not only did their EEGs improve, but so did the aggression. In March 1993, S.G. Hayes of the University of Southern California School of Medicine reported that nine out of twenty-seven people (33%) with either treatment-resistant depression or treatment-resistant bipolar disorder had a permanent positive response to primidone. A plurality of subjects were also given methylphenobarbital in addition to or instead of primidone.