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an anticonvulsant used in the treatment of epilepsy; administered orally.


Apo-Primidone (CA), Mysoline

Pharmacologic class: Barbiturate

Therapeutic class: Anticonvulsant

Pregnancy risk category NR


Unknown. May raise seizure threshold by decreasing neuronal firing after being converted to phenobarbital.


Suspension: 250 mg/5 ml

Tablets: 50 mg, 250 mg

Indications and dosages

Grand mal, psychomotor, or focal epileptic seizures

Adults and children ages 8 and older: Initially, 100 to 125 mg P.O. at bedtime on days 1 to 3, then 100 to 125 mg P.O. b.i.d. on days 4 to 6, then 100 to 125 mg P.O. t.i.d. on days 7 to 9, followed by a maintenance dosage of 250 mg P.O. three or four times daily

Children younger than age 8: Initially, 50 mg P.O. at bedtime on days 1 to 3, then 50 mg P.O. b.i.d. on days 4 to 6, then 100 mg P.O. b.i.d. on days 7 to 9. For maintenance, 125 to 250 mg t.i.d. or 10 to 25 mg/kg/day in divided doses.

Dosage adjustment

• Renal impairment

Off-label uses

• Benign familial (essential) tremor


• Hypersensitivity to drug or phenobarbital

• Porphyria


Use cautiously in:

• hepatic, renal, or chronic obstructive pulmonary disease

• pregnant or breastfeeding patients

• hyperactive children.


• Don't change brands. Bioequivalency problems have occurred.

Don't stop therapy suddenly. Dosage must be tapered.

• Know that drug may be given alone or with other anticonvulsants.

Adverse reactions

CNS: headache, dizziness, stimulation, drowsiness, sedation, confusion, hallucinations, psychosis, ataxia, vertigo, hyperirritability, emotional disturbances, paranoid symptoms, coma

EENT: diplopia, nystagmus, eyelid edema

GI: nausea, vomiting, anorexia

GU: erectile dysfunction

Hematologic: megaloblastic anemia,


Skin: flushing, rash


Drug-drug. Acetazolamide, succinimide: decreased primidone blood level Carbamazepine: decreased primidone blood level, increased carbamazepine blood level

Hydantoins, isoniazid, nicotinamide: increased primidone blood level

Drug-diagnostic tests. Hemoglobin, platelets: decreased levels

Liver function tests: altered results

Patient monitoring

• Monitor primidone and phenobarbital blood levels.

• Monitor CBC and blood chemistry. Watch for evidence of blood dyscrasias.

• Assess neurologic status regularly. Stay alert for excessive drowsiness and emotional status changes.

Patient teaching

Caution patient not to discontinue therapy suddenly. Advise him to discuss dosage changes with prescriber.

Instruct patient to immediately report unusual bleeding, bruising, or rash.

• Tell patient drug may cause sexual dysfunction. Advise him to discuss this issue with prescriber.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration, vision, and alertness.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.


/prim·i·done/ (prim´ĭ-dōn) an anticonvulsant used in the treatment of generalized tonic-clonic, nocturnal myoclonic, and partial seizures.


an anticonvulsant.
indications It is prescribed in the treatment of seizure disorders, including tonic-clonic, psychomotor, and focal epilepsy-like seizures, and has an unlabeled use for treating familial (essential) tremor.
contraindications Porphyria, pregnancy, or known hypersensitivity to this drug or to phenobarbital, a metabolite of primidone, prohibits its use. The drug must be used with caution in those having renal, hepatic, or pulmonary insufficiency.
adverse effects The most serious adverse effect, seen on rare occasions, is megaloblastic anemia. Drowsiness, ataxia, and dizziness are common. Drug dependency and other adverse effects of phenobarbital may occur.


Desoxyphenobarbital Neurology An anticonvulsant used as a monotherapy for partial seizures–eg, secondary generalized seizures. See Phenobarbital, Seizures.


An ANTICONVULSANT drug used in the treatment of EPILEPSY. A brand name is Mysoline.


an anticonvulsant related to phenobarbital. Used in dogs to control seizures of epilepsy and encephalitis.
References in periodicals archive ?
A 68-year-old woman presented to our emergency department with nausea, vomiting, perspiration, and somnolence after taking a primidone (Mysoline, Keymen ilag San.
Moreover, a 2010 study of 223 ET patients in a clinical database revealed that more than half of patients taking primidone and/or propranolol had discontinued them, suggesting that the need for alternatives is great (Parkinsonism Relat.
Zesiewicz said in an interview, adding that patients not responding to primidone or propranolol, or in whom these are contraindicated, might benefit from any of the currently recommended second-line agents with level B evidence supporting them.
A comprehensive review of the evidence-based literature published since 1999 revealed that daily treatment with phenobarbital, primidone, and valproic acid--and intermittent treatment with oral diazepam at the time of fever--reduces the occurrence of recurrent febrile seizures, whereas daily carbamazepine and phenytoin do not.
to manufacture primidone tablets (50/250 mg), cyclobenzaprine tablets (10 mg) and demeclocycline tablets (150/300 mg).
food records, food frequency or typical intake interview) Table 2 Medication-Nutrient interactions associated with medications frequently prescribed for children with special healthcare needs Medications Use Drug Nutrient Interaction Carbamazepine (Tegretol), Anticonvulsants Decreased folic phentoin (Dilantin), acid levels with phenybarbital, primidone concurrent increased (Mysoline) Valproic Acid homocysteine levels.
The most commonly used drugs are carbamazepine (Calepsin[R]), benzodiazepines (for example, clonazepame [Klonopin[R]]), barbiturates (for example, phenobarbital [Luminal[R]]), primidone (Mysoline[R]), phenytoin (Dilantin[R]), ethosuximide (Zarontin[R]), gabapentin (Neurontin[R]), tiagabine (Gabitril[R]), topiramate (Topamax[R]), and valproate (Depacon[R]) (Glauser et al.
In their survey, less than 5% of respondents knew the pharmacokinetic drug interaction between oral contraceptives and six common antiepileptic drugs (carbamazepine, ethosuximide, phenytoin, phenobarbital, primidone, and valproic acid).
Backup contraception would be warranted when taking phenytoin, carbamazepine, primidone, ethosuximide, methylphenobarbital, paramethadione, Phenobarbital, topiramate, rifampin, or griseofulvin and St John's wort.
Beta blockers, normally used to treat high blood pressure, often work, as does Primidone, the antiseizure drug.
Acute diphenylhydantoin and primidone poisoning treated by peritoneal dialysis.