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NERVOUS SYSTEM › ANTIEPILEPTICS › ANTIEPILEPTICS › Barbiturates and derivatives
primidone
N03AA03
Forms & Strengths
- Tablets: 50 mg, 250 mg
- Oral suspension
Adult Dosing
- Initial dose: 100-125 mg at bedtime, increasing to 250 mg/day after 3 days, then 250-375 mg/day in 2-3 divided doses
- Maximum dose: 500-750 mg/day
- Maintenance dose: 250-1000 mg/day in 2-3 divided doses
Pediatric Dosing
- Initial dose: 50 mg at bedtime, increasing to 125-250 mg/day after 3 days
- Children under 8 years: 50-100 mg/day in 2 divided doses
- Children 8-16 years: 100-250 mg/day in 2 divided doses
Indications
- Epilepsy, including partial seizures, generalized seizures, and seizures associated with Lennox-Gastaut syndrome
- Essential tremor
Mechanism of Action
- Inhibits post-tetanic potentiation at synapses
- Enhances inhibitory neurotransmission via GABA
- Blocks repetitive neuronal discharges
Contraindications
- Porphyria
- Hypersensitivity to primidone, phenobarbital, or other barbiturates
Adverse Reactions
- Drowsiness
- Ataxia
- Nausea and vomiting
- Dizziness
- Rash
- Bone marrow suppression
- Megaloblastic anemia
Drug Interactions
- Phenobarbital, carbamazepine, and phenytoin: decreased primidone levels
- Valproic acid, isoniazid, and certain antidepressants: increased primidone levels
- Concomitant use with other CNS depressants: increased sedation
Curated Content: Needs Vetting Before Put to Clinical Use