
(pri’ mi done)
Apo-Primidone (CAN), Mysoline
PREGNANCY CATEGORY D
Drug Classes
Anticonvulsant
Antiepileptic
Barbiturate
Therapeutic Actions
Mechanism of action not understood; primidone and its two metabolites, phenobarbital and phenylethylmalonamide, all have antiepileptic activity.
Indications
Control of tonic-clonic, psychomotor, or focal epileptic seizures, either alone or with other antiepileptics; may control tonic-clonic seizures refractory to other antiepileptics
Unlabeled use: Treatment of benign familial tremor (essential tremor)—750 mg/day
Contraindications and Cautions
Contraindicated with hypersensitivity to barbiturates and primidone, porphyria, lactation (somnolence and drowsiness may occur in breast-feeding newborns).
Use cautiously with pregnancy (association between use of antiepileptics and an elevated incidence of birth defects; however, do not discontinue antiepileptic therapy in pregnant women who are receiving such therapy to prevent major seizures; discontinuing medication is likely to precipitate status epilepticus, with attendant hypoxia and risk to both mother and fetus; to prevent neonatal hemorrhage, primidone should be given with prophylactic vitamin K1 therapy for 1 mo before and during delivery); sleep apnea, depression, history of substance abuse, renal or hepatic impairment.
Available Forms
Tablets—50, 250 mg
Dosages
Adults
Regimen for patients who have received no previous therapy: Days 1–3, 100–125 mg PO at bedtime; days 4–6, 100–125 mg PO bid; days 7–9, 100–125 mg PO tid; day 10–maintenance, 250 mg tid. The usual maintenance dosage is 250 mg tid–qid. If required, increase dosage to 250 mg five to six times daily, but do not exceed dosage of 500 mg qid (2 g/day).
Regimen for patients already receiving other antiepileptics: Start primidone at 100–125 mg PO at bedtime. Gradually increase to maintenance level as the other drug is gradually decreased. Continue this regimen until satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn. When use of primidone alone is desired, the transition should not be completed in less than 2 wk.Stay updated, free articles. Join our Telegram channel
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