Barbiturate-derived antiepileptic
Primidone
Brand names: Mysoline
Adult dose
Dose: Initial 125mg ON, increase by 125mg every 3 days; usual 0.5–1.5g/day in 2 divided doses. Essential tremor: 25–250mg ON
Route: PO
Frequency: BD or ON
Clinical pearls
- Essential tremor (2nd-line after propranolol); generalised tonic-clonic seizures
- Largely superseded; metabolised to phenobarbital
Contraindications
- Acute porphyria
- Severe respiratory disease
- Hypersensitivity
Side effects
- Sedation
- Ataxia
- Megaloblastic anaemia
- Osteomalacia
- Connective tissue disorders
- Withdrawal seizures
Interactions
- Many — strong enzyme inducer
- Hormonal contraceptives
- Anticoagulants
- Many AEDs
Monitoring
- FBC
- LFTs
- Drug levels (rarely)
Reference: BNF; NICE NG217; https://bnf.nice.org.uk/drugs/primidone/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Pathways
- Acute Stroke / TIA Assessment · NICE NG128; RCP Stroke Guidelines 2023
- Status Epilepticus (Adults) · NICE CG137; ESEM guidelines; RCP Neurology Guidelines
- Suspected Subarachnoid Haemorrhage · NICE NG228; RCEM 2023; AHA/ASA 2023
- Adult Head Injury · NICE NG232 (2023)
- Bell's Palsy / Facial Nerve Palsy · ENT UK 2017; AAN
- Vertigo Workup · ENT UK; NICE CKS