Generic
Primidone
2 brands available in the market
At a glance
Primidone, used alone or with other anticonvulsants, is indicated for the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy.
Description
Primidone raises electro- or chemoshock seizure thresholds or alters seizure patterns in experimental animals. The mechanism of primidone's antiepileptic action is not known. Primidone per se has anticonvulsant activity as do its two metabolites, phenobarbital and phenylethylmalonamide (PEMA). PEMA potentiates the anticonvulsant activity of phenobarbital in experimental animals.
Indications
- Grand mal seizures
- Psychomotor seizures
- Focal epileptic seizures
Therapeutic class
Adjunct anti-epileptic drugs
Pharmacological class
Barbiturate (Anticonvulsant)
Pharmacology
Primidone raises electro- or chemoshock seizure thresholds in animal models. Primidone itself has anticonvulsant activity, as do its metabolites phenobarbital and PEMA. PEMA potentiates the anticonvulsant activity of phenobarbital.
Mechanism of action
Raises seizure threshold and controls seizure activity.
Dosage
Adults and ≥8 years (Oral):
- Days 1-3: 100-125 mg at bedtime
- Days 4-6: 100-125 mg twice daily
- Days 7-9: 100-125 mg three times daily
- Day 10-maintenance: 250 mg three times daily
- Usual maintenance: 250 mg 3-4 times daily (max 500 mg four times daily)
- Maximum daily dose: 2 g
Administration
- Take at the same time each day
- Gradually increase dose as prescribed by your doctor
Missed dose
If you miss a dose, take it as soon as you remember; skip if it's almost time for next dose; do not double the dose.
Side effects
Common Side Effects:
- Ataxia
- Vertigo
- Nausea
- Anorexia
- Vomiting
- Fatigue
- Hyperirritability
- Emotional disturbances
- Diplopia
- Nystagmus
- Drowsiness
- Morbilliform skin eruptions
- Granulocytopenia
- Agranulocytosis
- Aplastic anemia
- Megaloblastic anemia
Precautions & warnings
- Complete blood count and SMA-12 test every 6 months with prolonged therapy
- Substantial amounts excreted in breast milk; discontinue nursing if newborn shows undue somnolence
Contraindications
- Hypersensitivity to primidone or any component
Drug interactions
- Other sedative drugs or alcohol: Effects potentiated
Food interactions
It is not known whether it is safe to consume alcohol with Primidone.
Use in pregnancy
Use in Pregnancy: Effects in pregnancy unknown; animal studies have shown fetal abnormalities; use if potential benefit justifies potential risk.
Pregnancy Category: D — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Substantial amounts excreted in milk; discontinue nursing if newborn shows undue somnolence.
Pediatric use
Pediatric dose based on age; consult your doctor.
Geriatric use
Caution required in elderly patients; dose adjustment may be needed.
Renal / hepatic impairment
Renal Impairment: Caution in kidney disease; dose adjustment may be needed; consult your doctor.
Hepatic Impairment: Caution in liver disease; dose adjustment may be needed; consult your doctor.
Overdose effects
Overdose: Ataxia, drowsiness, diplopia, nystagmus, coma, respiratory depression; treatment: gastric lavage, activated charcoal, supportive care.
Storage conditions
Store below 30°C, away from light and moisture; keep out of reach of children.
Chemical structure
Primidone