Primidone

Registered South African indications: 

• Epilepsy 
• Myoclonic jerks
• Akinetic attacks 

Contraindications

• Hypersensitivity to the active ingredient or any of its excipients 
• Acute intermittent porphyria  

Cautions

• Pregnancy 
• Breastfeeding 
• Renal impairment 
• Hepatic impairment 
• Elderly 
• Children
• Debilitated patients
• Impaired respiratory function 
• Prolonged use 
• Abrupt withdrawal

Forms avail. in SA and covered in this monograph: tab 

Generalized tonic-clonic seizures
Partial seizures with or without secondary generalization
Myoclonic jerks
Akinetic attacks

• Oral (tab): Initial: 125mg, dly at night; Titrate by 125mg at intervals of 3 days, until patient receiving 500mg/day, in 2 divided doses; Then titrate by 250mg at intervals of 3 days; Maintenance: 750-1500mg/day, in 2 divided doses; Max: 1500mg/24hrs

In certain patients, it may be considered advisable to give a larger dose when the seizures are more frequent

When used with or to replace existing anticonvulsant therapy, the dosage should be increased gradually while the other medication is maintained or decreased gradually over a period of 2 weeks in order to maintain seizure control

Paed. forms avail. in SA and covered in this monograph: tab 

Generalized tonic-clonic seizures
Partial seizures with or without secondary generalization
Myoclonic jerks
Akinetic attacks

Younger than 2 years

• Oral (tab): Day 1-3: 50mg, dly at night; Day 4-6: 50mg, 12hrly; Day 7-9: 100mg, 12hrly; Maintenance: 250-500/day, in 2 divided doses; Max: 1000mg/24hrs

Between 2-5 years

• Oral (tab): Day 1-3: 50mg, dly at night; Day 4-6: 50mg, 12hrly; Day 7-9: 100mg, 12hrly; Maintenance: 500-750/day, in 2 divided doses; Max: 1000mg/24hrs

Between 5-8 years 

• Oral (tab): Day 1-3: 50mg, dly at night; Day 4-6: 50mg, 12hrly; Day 7-9: 100mg, 12hrly; Maintenance: 750-1000mg/day, in 2 divided doses; Max: 1000mg/24hrs

Older than 8 years

• See adult dosage 

In certain patients, it may be considered advisable to give a larger dose when the seizures are more frequent 

When used with or to replace existing anticonvulsant therapy, the dosage should be increased gradually while the other medication is maintained or decreased gradually over a period of 2 weeks in order to maintain seizure control 

Pregnancy

• FDA Pregnancy Category Not Rated (NR) 

Breastfeeding

• Caution

Renal Impairment 

• Caution; no dose adjustment recommended

Hepatic Impairment 

• Caution; no dose adjustment recommended

Elderly 

• Caution; no dose adjustment recommended

Central Nervous System Disorders

• Listlessness
• Ataxia
• Nystagmus
• Headache
• Dizziness
• Personality changes
• Psychotic reactions

Gastrointestinal Disorders

• Nausea and vomiting

Hepatobiliary Disorders

• Increased hepatic enzymes 

Musculoskeletal Disorders 

• Arthralgia
• Osteomalacia
• Dupuytren's contracture

Skin and Subcutaneous Tissue Disorders

• Maculopapular rash
• Morbilliform rash
• Scarlatiniform rash
• Exfoliative dermatitis
• Stevens-Johnson syndrome
• Toxic epidermal necrolysis
• Lupus erythematosus

Immune, Blood and Lymphatic System Disorders

• Allergic reactions
• Megaloblastic anaemia
• Blood dyscrasias

Sensory Disorders 

• Visual disturbances

• CYP3A4 inhibitors 
• CYP450 inducers 
• St. John's Wort 
• Theophylline 
• Central nervous system depressants 
• Beta blockers
• Carbamazepine
• Cyclosporin
• Clozapine
• Chloramphenicol
• Corticosteroids
• Cyclophosphamide
• Dicoumarins
• Doxycycline
• Ethosuxamide
• Etoposide
• Felbamate
• Granisetron
• Lamotrigine
• Losartan
• Metronidazole
• Mianserin
• Nimodipine
• Oral contraceptives
• Oxcarbazepine
• Phenytoin
• Quinidine
• Rocuronium
• Sodium valproate
• Tiagabine
• Topiramate
• Tricyclic antidepressants
• Vecuronium
• Warfarin
• Zonisamide
• Paracetamol
• Androgens
• Montelukast
• Nelfinavir
• Methadone
• Digoxin 

• Full blood count
• Blood glucose 
• Serum lipids

Specific cases may require

• Renal function
• Serum primidone concentration
• Serum phenobarbital concentration

Primidone is a barbiturate with two active metabolites, phenobarbital and phenylethylmalonamide, which each have anticonvulsant properties. It raises the seizure threshold, decreases neuron excitability and alters seizure patterns. In addition to its anticonvulsant activity, primidone may potentiate the action of phenobarbital.

Tablet 250mg

• Mysoline (Pharmaplan)