Phenobarbitone

Registered South African indications: 

• Prophylactic treatment of epilepsy of a convulsive type
• General sedative

Registered South African contraindications

• Hypersensitivity to the active ingredient or any of its excipients
• Hypersensitivity to barbiturates
• Acute intermittent porphyia
• Severe respiratory depression
• Severe renal or hepatic impairment

• Pregnancy
• Breastfeeding
• Mild to moderate renal impairment
• Mild to moderate hepatic impairment
• Elderly
• Respiratory depression
• Young patients
• Debilitated patients
• Senile patients
• Abrupt withdrawal
• Acute on chronic pain
• Prolonged use
• History of drug abuse
• Alcoholism
• Galactose intolerance
• Lapp lactase deficiency 
• Glucose-galactose malabsorption
• May impair ability to drive and operate machinery

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

South African registered indications and dosages

Prophylactic treatment of epilepsy of a convulsive type

• Oral (tab): 30mg, taken morning and at night

General sedative

• Oral (tab): 30mg, taken 3 times a day

Hypnotic

• Oral (tab): 30mg, taken 1hr before bedtime

Abrupt withdrawal of phenobarbitone may result in a severe abstinence syndrome, which includes grand mal seizures and delirium. Withdrawal of treatment in these cases should be cautious and gradual

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

Paed. dosages below include:

• South African Standard Treatment Guidelines indications and dosages
• South African registered indications and dosages

South African Standard Treatment Guidelines indications and dosages

• Click here for the Alimentary Tract Chapter (Standard Treatment Guidelines And Essential Medicines List For South Africa, Hospital Level, Paediatrics, 2023 Edition)
• Click here for the Nervous System Chapter (Standard Treatment Guidelines And Essential Medicines List For South Africa, Hospital Level, Paediatrics, 2023 Edition)
• Click here for the Child and Adolescent Psychiatry Chapter (Standard Treatment Guidelines And Essential Medicines List For South Africa, Hospital Level, Paediatrics, 2023 Edition)
• Click here for the Prematurity and Neonatal Conditions Chapter (Standard Treatment Guidelines And Essential Medicines List For South Africa, Hospital Level, Paediatrics, 2023 Edition)

South African registered indications and dosages

• No specific recommendation provided

Pregnancy

• Caution; positive evidence of risk
• Phenobarbital therapy in epileptic pregnant women presents a risk to the foetus in terms of major and minor congenital defects such as congenital craniofacial, digital abnormalities and, less commonly, cleft lip and palate. The risk of teratogenic effects developing appears to be greater if more than one antiepileptic drug is administered. The risk to the mother, however, is greater if phenobarbital is withheld and seizure control is lost. The risk: benefit balance, in this case, favours continued use of the drug during pregnancy at the lowest possible level to control seizures
• Patients taking phenobarbital should be adequately supplemented with folic acid before conception and during pregnancy. Folic acid supplementation during pregnancy can help to reduce the risk of neural defects to the infant
• Phenobarbital readily crosses the placenta following oral administration and is distributed throughout foetal tissue, the highest concentrations being found in the placenta, fetal liver and brain. Adverse effects on neurobehavioral development have also been reported
• Haemorrhage at birth and addiction are also a risk. Prophylactic treatment with vitamin K1 for the mother before delivery (as well as the neonate) is recommended, the neonate should be monitored for signs of bleeding

Breastfeeding

• Caution; not recommended
• Phenobarbital is excreted into breast milk and there is a small risk of neonatal sedation. Breastfeeding is therefore not advisable

South African recommendations

• Mild to moderate: Caution; no dose adjustment recommended
  Phenobarbitone should be used with care in patients with impaired renal function
• Severe: Contraindicated

South African recommendations

• Mild to moderate: Caution; no dose adjustment recommended
  Phenobarbitone should be used with care in patients with impaired hepatic function
• Severe: Contraindicated

South African recommendations

• Caution; dose adjustment recommended
  Phenobarbitone should be administered cautiously to the elderly; reduced dosage should be employed until tolerance is assessed

Central Nervous System Disorders

• Hyperactivity
• Behavioural disturbances in children
• Ataxia
• Nystagmus
• Paradoxical reactions
• Hallucinations
• Restlessness 
• Confusion in the elderly
• Mental depression
• Memory and cognitive impairment
• Drowsiness
• Lethargy

Cardiovascular Disorders

• Hypotension

Respiratory Disorders

• Respiratory depression

Hepatobiliary Disorders

• Hepatitis
• Cholestasis

Musculoskeletal Disorders

• Osteomalacia
• Rickets
• Decreased bone mineral density
• Osteopenia
• Osteoporosis
• Fractures

Skin and Subcutaneous Tissue Disorders

• Allergic skin reactions 
• Exfoliative dermatitis
• Erythema multiforme
• Stevens-Johnson syndrome 
• Toxic epidermal necrolysis

Immune, Blood and Lymphatic System Disorders

• Megaloblastic anaemia 
• Agranulocytosis
• Thrombocytopenia
• Hypersensitivity syndrome

• Central nervous system depressants 
• Antidepressants 
• Antiepileptics
• Antipsychotics
• Folic acid
• Memantine 
• Methylphenidate
• St John's wort 
• Anti-arrhythmics
• Antibacterials
• Anticoagulants
• Antifungals
• Antivirals 
• Anxiolytics
• Hypnotics
• Aprepitant
• Beta blockers
• Calcium channel blockers 
• Cardiac glycosides
• Ciclosporin 
• Tacrolimus
• Corticosteroids
• Cytotoxics
• Diuretics 
• Hormone antagonists
• Methadone
• Montelukast
• Oestrogens
• Progestogens
• Sodium oxybate
• Theophylline
• Thyroid hormones
• Tibolone
• Tropisetron
• Vitamins 

• Renal function
• Hepatic function
• Full blood count

Specific cases may require

• Phenobarbital serum concentrations

Phenobarbitone is a long acting barbituate acting by depression of the central nervous system.

Tablet 30mg 

• Lethyl (Pharmacare) 
• Sedabarb (Ranbaxy)

COMBINATION PREPARATIONS

Thiamine/ Nicotinamide/ Phenobarbital/ Pyridoxine (Vit B6)/ Riboflavin (Vit B2)

Syrup (per 5ml) 3mg/10mg/16mg/0.25mg/1mg

• Adco-Phenobarb Vitalet (Adcock)

Caffeine/ Codeine/ Paracetamol/ Diphenhydramine/ Phenobarbital

Tablet 50mg/10mg/400mg/5mg/8mg

• Propain Forte (Adcock) originator

Atropine/ Hyoscine Hbr/ Hyoscine Sulphate/ Phenobarbitone

Tablet 0.02mg/0.006mg/0.104mg/15mg

• Millerspas (Pharmacare)