Folic acid had been found to alleviate the symptoms of megaloblastic anemia in the 1940s, not long after it was discovered, but the typical patient only made a full recovery—cessation of CNS and PNS symptoms as well as anemia—on B12 therapy. Five years earlier, folic acid deficiency was linked to birth defects in rats. Primidone was seen by some as too valuable to withhold based on the slight possibility of this rare side effect and by others as dangerous enough to be withheld unless phenobarbital or some other barbiturate failed to work for this and other reasons (i.e., reports of permanent psychosis). Available forms
Primidone is available as a 250 mg/5mL suspension, and in the form of 50 mg, 125 mg, and 250 mg tablets. It is also available in a chewable tablet formulation in Canada.It is marketed as several different brands including Mysoline (Canada, Ireland, Japan, the United Kingdom, and the United States), Prysoline (Israel, Rekah Pharmaceutical Products, Ltd.), Apo-Primidone, Liskantin (Germany, Desitin), Resimatil (Germany, Sanofi-Synthélabo GmbH), Mylepsinum (Germany, AWD.pharma GmbH & Co., KG)., and Sertan (Hungary, 250 mg  tablets, ICN Pharmaceuticals Inc.[1])

Other animals
Primidone has veterinary uses, including the prevention of aggressive behavior and cannibalism in gilt pigs, and treatment of nervous disorders in dogs and other animals. References
Further reading
"Toxicology and Carcinogenesis Studies of Primidone in F344/N Rats and B6C3F1 Mice (Feed Studies)" (PDF). Department of Health and Human Services National Toxicology Program. September 2000. Lay summary. {{cite web}}: Cite uses deprecated parameter |lay-url= (help)

External links
"Primidone". Drug Information Portal. U.S. National Library of Medicine.
Because of this, primidone is a Category D medication.Primidone, like phenobarbital and the benzodiazepines, can also cause sedation in the newborn and also withdrawal within the first few days of life; phenobarbital is the most likely out of all of them to do that.In May 2005, Dr. M. Lopez-Gomezs team reported an association between the use of primidone and depression in epilepsy patients; this same study reported that inadequate seizure control, posttraumatic epilepsy, and polytherapy were also risk factors. Polytherapy was also associated with poor seizure control. Out of all of the risk factors, usage of primidone and inadequate seizure control were the greatest; with ORs of 4.089 and 3.084, respectively. They had been looking for factors associated with depression in epilepsy patients. Schaffer et al. 1999 reported that one of their treatment failures, a 45-year-old woman taking 50 mg a day along with lithium 600 mg/day, clozapine 12.5 mg/day, trazodone 50 mg/day, and alprazolam 4 mg/day for three and a half months experienced auditory hallucinations that led to discontinuation of primidone. It can also cause hyperactivity in children; this most commonly occurs at low serum levels. There is one case of an individual developing catatonic schizophrenia when her serum concentration of primidone went above normal.Primidone is one of the anticonvulsants associated with anticonvulsant hypersensitivity syndrome, others being carbamazepine, phenytoin, and phenobarbital.