primidone: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
primidone: clinical details
Prescribing considerations
- Introduce and adjust cautiously to limit dizziness, ataxia, nausea and sedation.
- Avoid abrupt withdrawal because seizures or status epilepticus may occur.
- Review renal, hepatic and respiratory impairment, frailty and older age.
- Undertake a comprehensive interaction review.
- For epilepsy, maintain continuity of a specific manufacturer’s product.
- Discuss pregnancy risks, effective contraception and pre-conception review where relevant.
Contraindications and cautions
- Hypersensitivity to primidone, phenobarbital or product excipients
- Acute intermittent porphyria
- Contraindicated interacting medicines specified in current product information
- Previous primidone- or phenobarbital-associated SJS, TEN or DRESS
Monitoring
- Clinical response, adherence, seizure pattern or tremor control
- Sedation, ataxia, visual effects and falls risk
- Rash or systemic hypersensitivity, particularly early in treatment
- Mood, suicidal thoughts and behavioural change
- Renal and hepatic status where impairment affects handling
- Blood counts if symptoms suggest cytopenia or megaloblastic anaemia
- Bone health and vitamin D risk during long-term treatment
- Interactions and loss of efficacy when co-medication changes
Clinical pharmacology
Primidone is rapidly absorbed and partly metabolised in the liver to phenobarbital and PEMA, both with antiseizure activity. Primidone and phenobarbital induce hepatic enzymes; phenobarbital has substantially more prolonged elimination than primidone.
Formulation and product differences
- The selected Enodama product is a white to off-white, uncoated, unscored tablet intended to be swallowed whole with water.
primidone preparations and strengths
Tablet
Route: Oral
Strengths: 50 mg, 125 mg, 250 mg
primidone interactions
Primidone and phenobarbital strongly induce liver enzymes and can reduce the effectiveness of many medicines. An interaction check is important when anything is started, stopped or changed.
Hormonal contraceptives
May be less effective; discuss alternative or additional contraception.
Warfarin and related vitamin K antagonists
Anticoagulant effect may change and closer INR monitoring may be needed when primidone is started, stopped or changed.
Apixaban, dabigatran and rivaroxaban
May reduce anticoagulant exposure and protection against clots; these combinations are not recommended in the selected product information.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.