Consumer medicine information

What is in this leaflet

This leaflet answers some common questions about Phenobarbitone Injection. It does not contain all of the available information. It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you using it against the benefits they expect it will have.

If you have any concerns about the use of this medicine ask your doctor or pharmacist.

Keep this leaflet with the medicine. You may need to read it again.

What Phenobarbitone Injection is used for

The active ingredient is called phenobarbital (phenobarbitone) sodium.

It belongs to a group of medicines called barbiturates, which act by inducing sleep and stopping convulsions.

Phenobarbitone Injection is used for treatment of grand mal and psychomotor epilepsy and sedation.

Ask your doctor if you have any questions about why Phenobarbitone Injection has been prescribed for you. Your doctor may have prescribed it for another purpose.

Phenobarbitone Injection is available only with a doctor’s prescription.

The use of barbiturates may lead to dependence on this medicine.

Before it is given

When it must not be used

Phenobarbitone Injection should not be used if you are allergic to:

• phenobarbital (phenobarbitone) sodium
• any of the other ingredients listed at the end of this leaflet
• any other barbiturate.

Some of the symptoms of an allergic reaction may include red, itchy skin rashes; difficulty breathing; hay fever; swelling of the face or throat or faintness.

Do not use if you have or have had any of the following medical conditions:

• porphyria (a rare blood pigment disorder)
• severe anaemia (a disease of the blood with reduced number of red blood cells) if it is due to folate deficiency
• uncontrolled severe asthma
• severe respiratory depression
• uncontrolled diabetes mellitus or sugar diabetes
• acute intoxication with alcohol, hypnotics or analgesics
• intoxication with stimulants or depressant psychotropic agents
• alcoholism or drug dependence
• severe liver or kidney problems
• severe depression or suicidal tendencies
• short or long term serious or chronic pain.

Phenobarbitone Injection should not be given to unusually overactive children.

Do not use after the expiry date (EXP) printed on the pack.

Do not use if the packaging is torn or shows signs of tampering.

Before you are given it

You must tell your doctor if you:

• are allergic to any other medicines or any foods, dyes or preservatives
• have or have had any other medical conditions or health problems, including:
  - high/low blood pressure
  - heart problems
  - lung problems
  - hyperthyroidism, an overactive thyroid gland
  - hypoadrenalism (borderline), an underfunction of the adrenal gland
  - a depressive illness
  - asthma
• are a heavy drinker
• have a drug dependency.

Tell your doctor immediately if you become pregnant or think you may be pregnant while on treatment with Phenobarbitone Injection. Phenobarbitone Injection may affect your developing baby if you take it during pregnancy. However, it is very important to control your fits while you are pregnant. If it is necessary for you to take Phenobarbitone Injection, your doctor can help you decide whether or not to take it during pregnancy.

Tell your doctor if you intend to become pregnant.

Your doctor may ask you to:

• undergo a pregnancy test to rule out pregnancy prior to starting on this medicine.
• use other effective contraceptive methods instead of the ‘pill’ as this medicine can interact with the oral contraceptive pill making it less effective.

Your doctor will advise you about other possible medication options prior to conception and before contraception is discontinued.

Use during breast-feeding

Tell your doctor if you are breastfeeding or plan to breastfeed. This medicine is not recommended for use while breastfeeding as it passes into breast milk and may cause serious side effects to your baby.

Use in the elderly

Elderly patients are more likely to have less effective kidney or liver function. This may increase the risk of side effects.

If you have not told your doctor about any of the above, tell them before Phenobarbitone Injection is used.

Taking other medicines

Tell your doctor if you are taking any other medicines, including medicines that you buy without a prescription from a pharmacy, supermarket or health food shop.

Some medicines may interact with Phenobarbitone Injection. These include:

• other medications used to treat epilepsy
• anticoagulants, medicines used to treat clots eg. warfarin
• painkillers, paracetamol and stronger narcotic agents
• antidepressants, medicines used to treat depression
• anti-arrhythmics, medicines used to treat irregular heart beats eg. quinidine, disopyramide
• antibiotics and antifungal agents, medicines used to treat infections including AIDS
• calcium channel blockers, medicines used to treat high blood pressure and angina
• antipsychotics, medicines used to treat certain mental and emotional conditions
• chemotherapy drugs, used to treat cancer
• corticosteroids, such as prednisolone, cortisone
• medicines used to treat heart failure eg. digoxin
• oral contraceptives
• immunosuppressive medicines, used to lower your body’s resistance to disease e.g. cyclosporin, tacrolimus
• medicines used to stop you from feeling pain, e.g. anaesthetic agents
• disulfiram, a medicine used to treat alcoholism
• urinary alkalinisers
• antihistamines, medicines used to prevent or relieve symptoms of allergy
• theophylline, a medicine used to treat asthma
• beta-blockers e.g. propranolol, used to treat high blood pressure and heart conditions
• other medications that interact with alcohol.

These medicines may be affected by Phenobarbitone Injection or may affect how well it works. You may need different amounts of your medicine or you may need to take different medicines. Your doctor or pharmacist has more information on medicines to be careful with or avoid while being given Phenobarbitone Injection.

How it is given

How much is given

The recommended dose of Phenobarbitone Injection varies depending on your condition. Your doctor will determine how much is appropriate.

How it is given

Except under unusual circumstances, Phenobarbitone Injection should be administered by a health care professional.

How long to have it for

Phenobarbitone Injection should be given for as long as recommended by your doctor.

If symptoms persist, see your doctor.

If too much is given (overdose)

Immediately telephone your doctor or the Poisons Information Centre (telephone 13 11 26) for advice or go to casualty at your nearest hospital, if you think that you or anyone else may have been given too much Phenobarbitone Injection.

Do this even if there are no signs of discomfort or poisoning.

Also report any other medicine or alcohol (including any barbiturates or narcotics) which has been taken. You may need urgent medical attention.

Symptoms of overdose may include weakness, dizziness, lethargy, nausea, vomiting, sweating, underbreathing, shock, impairment of consciousness, collapse of circulation, mental confusion and hypotension.

While you are being given it

Things you must do

Tell your doctor if you become pregnant while you are being given Phenobarbitone Injection.

Tell your doctor if you want to take oral contraceptives while being given Phenobarbitone Injection. You may need a higher dose of oral contraceptives than usual to prevent pregnancy or you may need to consider other forms of contraception.

If you need any medical tests while you are being given Phenobarbitone Injection, tell your doctor as it may affect the results of some tests.

Always discuss with your doctor any problems or difficulties during or after being given Phenobarbitone Injection. Your doctor may want to take some tests from time to time to help prevent unwanted side effects.

Things you must not do

Do not use any other medicines while you are being given Phenobarbitone Injection without first telling your doctor.

Do not drive or operate machinery while being given this medicine. Phenobarbitone Injection may cause drowsiness or dizziness in some people and therefore may affect alertness.

Things to be careful of

Be careful drinking alcohol while using Phenobarbitone Injection. If you drink alcohol, it could make some of the unwanted side effects of this medicine worse. Your doctor may suggest that you avoid alcohol completely or reduce the amount of alcohol you drink while Phenobarbitone Injection is being given.

Some people may experience side effects such as nausea, vomiting, constipation, drowsiness and dizziness, which may further affect the risk when driving or using dangerous machinery.

Side effects

Tell your doctor or pharmacist as soon as possible if you do not feel well while Phenobarbitone Injection is being given.

All medicines have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some of the side effects.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor if you notice any of the following common side effects and they worry you:

• pain or irritation at the site of injection
• rapid heartbeat
• nausea (feeling sick)
• constipation
• dizziness
• lethargy
• vomiting
• skin rashes
• sweating
• dry mouth
• confusion
• faintness
• irritability
• restlessness
• dependency (habit-forming)
• mood changes
• drowsiness
• hyperexcitability
• hangover
• sleep disturbances.

Tell your doctor immediately or go to Accident and Emergency at your nearest hospital if you notice any of the following symptoms:

• signs of infection e.g. fever, chills, sore throat, swollen glands, mouth ulcers
• easy or unusual bleeding or bruising under the skin
• nosebleed
• yellowing of the skin and eyes (jaundice)
• other sudden signs of allergy
• severe skin rash, itching, hives, blisters or peeling skin.

These are very serious side effects.

Tell your doctor immediately or go to the Accident and Emergency department of your nearest hospital if you have any thoughts of harming yourself or committing suicide.

Tell your doctor if you notice anything else that is making you feel unwell, even if you think the problems are not connected with this medicine and are not referred to in this leaflet. Other side effects not listed above may also occur in some patients.

Do not be alarmed by this list of possible side effects. You may not experience any of them.

After being given it

Storage

Phenobarbitone Injection is stored in the pharmacy or on the ward. The injection is kept in a cool dry place, where the temperature stays below 25°C.

Product description

What it looks like

Phenobarbitone Injection is a clear, colourless solution in a clear glass 1 mL ampoule.

It is for single use in one patient only.

Available in packs of 5 ampoules.

Ingredients

Active ingredient:

Each 1 mL ampoule contains phenobarbital (phenobarbitone) sodium 219 mg, equivalent to phenobarbitone 200 mg.

Inactive ingredients:

• propylene glycol
• ethanol
• water for injections.

Sponsor

Aspen Pharmacare Australia Pty Ltd
34-36 Chandos St
St Leonards NSW 2065
Australia

Australian Registration Number: AUST R 175471

This leaflet was revised in February 2022.

Published by MIMS May 2022

1 Name of Medicine

Phenobarbital (phenobarbitone) sodium.

2 Qualitative and Quantitative Composition

Phenobarbitone Injection contains phenobarbital (phenobarbitone) sodium 219 mg (equivalent to phenobarbitone 200 mg) per 1 mL ampoule.
Excipients include ethanol. For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Phenobarbitone Injection is a clear, colourless solution.

4 Clinical Particulars

4.9 Overdose

Clinical features. Overdosage of barbiturates produces CNS depression ranging from sleep to profound coma to death; respiratory depression which may progress to Cheyne-Stokes respiration, central hypoventilation, and cyanosis; cold, clammy skin and/or hypothermia or later fever, areflexia, tachycardia, hypotension, and decreased urine formation. Pupils are usually slightly constricted but may be dilated in severe poisoning. Patients with severe overdosage often experience typical shock syndrome; apnea, circulatory collapse, respiratory arrest and death may occur. Complications such as pneumonia, pulmonary oedema or renal failure may also prove fatal. Other complications which may occur are congestive heart failure, cardiac arrhythmias and urinary tract infections. Some patients have developed bullous cutaneous lesions which heal slowly.
Treatment. Treatment of overdosage is mainly supportive including maintenance of an adequate airway and assisted respiration and oxygen administration if needed. Standard treatment for shock should be administered if necessary. Activated charcoal may reduce absorption of phenobarbitone if given within one or two hours after ingestion. In patients who are not fully conscious or have impaired gag reflex, consideration should be given to administering activated charcoal via a nasogastric tube, once the airway is protected. Multiple dose, nasogastric administration of activated charcoal has been used effectively to treat phenobarbitone overdose; activated charcoal enhances the elimination of the drug and shortens the duration of coma. The patient's vital signs and fluid intake should be monitored closely. Analeptic drugs should not be administered because they may produce paroxysmal cerebral activity which may result in generalised seizures. In addition, it has been demonstrated that analeptics are incapable of stimulating respiration and exerting an arousal effect in patients with severe barbiturate poisoning and profound CNS depression. If renal function is normal, forced diuresis may be of benefit. In addition, alkalinisation of the urine increases renal excretion of phenobarbitone. Peritoneal dialysis or haemodialysis may be useful in severe barbiturate intoxication and/or if the patient is anuric or in shock.
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.3 Preclinical Safety Data

Published studies reported teratogenic effects (morphological defects) in rodents exposed to phenobarbital. Cleft palate is reported consistently in all preclinical studies, but other malformations are also reports (e.g. umbilical hernia, spina bifida, exencephaly, exomphalos plus fused ribs) in single studies or species. In addition, although data from the published studies are inconsistent, phenobarbital given to rats/mice during gestation or early postnatal period was associated with adverse neurodevelopment effects, including alterations in locomotor activity, cognition and learning patterns.
Genotoxicity. Genotoxicity studies for gene mutations and chromosome aberrations have given mixed results, however, tests for DNA damage or repair have been negative.
Carcinogenicity. Phenobarbitone sodium is carcinogenic in mice and in rats after lifetime administration. In mice, it produced benign and malignant liver cell tumours; in rats, benign liver cell tumours were observed. Phenobarbitone was negative in a 26 week bioassay in p53 heterozygous mice.
In a 29 year epidemiologic study of 9,136 patients who were treated on an anticonvulsant protocol that included phenobarbitone, results indicated a higher than normal incidence of hepatic carcinoma. Previously, some of these patients had been treated with thorotrast, a drug known to produce hepatic carcinomas. When patients who had received thorotrast were excluded, there was a nonsignificant increase in the number of liver tumours, and, unlike the mouse liver tumours, were mostly associated with cirrhosis.

6 Pharmaceutical Particulars

6.7 Physicochemical Properties

Phenobarbital (phenobarbitone) sodium is a white, odourless, hygroscopic powder, granules or flakes. It is very soluble in water and soluble in alcohol, practically insoluble in chloroform and ether. A 10% solution in water has a pH of not more than 10.2. Store in airtight containers.
Chemical structure.
https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSPHBSOD.gif Its molecular formula is C₁₂H₁₁N₂NaO₃. The molecular weight is 254.2.
CAS number. 57-30-7.

7 Medicine Schedule (Poisons Standard)

S4 (Prescription Only Medicine).

Summary Table of Changes

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