Consumer medicine information

Stelax

Baclofen

BRAND INFORMATION

Brand name

Stelax

Active ingredient

Baclofen

Schedule

SUMMARY CMI

STELAX Tablets

Consumer Medicine Information (CMI) summary

The full CMI on the next page has more details. If you are worried about using this medicine, speak to your doctor or pharmacist.

1. Why am I using Stelax?

Stelax contains the active ingredient baclofen. Stelax belongs to a group of medicines called muscle relaxants.

Stelax is used to reduce the stiffness or spasms in your muscles to help make you more mobile and able to manage your daily activities.

For more information, see Section 1. Why am I using Stelax? in the full CMI.

2. What should I know before I use Stelax?

Do not use if you have ever had an allergic reaction to Stelax or any of the ingredients listed at the end of the CMI.

Talk to your doctor if you have any other medical conditions, take any other medicines, or are pregnant or plan to become pregnant or are breastfeeding.

For more information, see Section 2. What should I know before I use Stelax? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with Stelax and affect how it works.

A list of these medicines is in Section 3. What if I am taking other medicines? in the full CMI.

4. How do I use Stelax?

Your doctor will tell you how many tablets of Stelax to take.
Do not exceed the recommended dose prescribed by your doctor.
Treatment is usually started in hospital with small doses of Stelax. The dose is then gradually increased to an amount that works best for you.

More instructions can be found in Section 4. How do I use Stelax? in the full CMI.

5. What should I know while using Stelax?

Things you should do	Remind any doctor, dentist or pharmacist you visit that you are using Stelax. Keep all doctor's appointments, so that your progress can be checked.
Things you should not do	Do not stop using this medicine suddenly, unless your doctor tells you to.
Driving or using machines	Be careful before you drive or use any machines or tools until you know how Stelax affects you. Stelax may cause sleepiness in some people, especially when you start taking it.
Drinking alcohol	Tell your doctor if you drink alcohol.
Looking after your medicine	Store the tablets in a cool dry place where temperature stays below 25°C. Keep out of reach of children.

For more information, see Section 5. What should I know while using Stelax? in the full CMI.

6. Are there any side effects?

Common side effects include daytime sleepiness, lack of energy, tiredness, dizziness or light-headiness, vertigo, confusion, headache, difficulty sleeping or nightmares, nausea, retching or vomiting, constipation, stomach cramps or diarrhoea, loss of appetite, stuffy nose, dry mouth, change in sense of taste, misuse, abuse and dependence, numbness, muscle weakness or spasms, swelling of ankles, blurred vision, ringing in the ears, frequent urination, excessive sweating, weight gain, impotence or inability to ejaculate, increased blood sugar, low body temperature.

For more information, including what to do if you have any side effects, see Section 6. Are there any side effects? in the full CMI.

FULL CMI

STELAX Tablets

Active ingredient(s): Baclofen

Consumer Medicine Information (CMI)

This leaflet provides important information about using Stelax. You should also speak to your doctor or pharmacist if you would like further information or if you have any concerns or questions about using Stelax.

Where to find information in this leaflet:

1. Why am I using Stelax?
2. What should I know before I use Stelax?
3. What if I am taking other medicines?
4. How do I use Stelax?
5. What should I know while using Stelax?
6. Are there any side effects?
7. Product details

1. Why am I using Stelax?

Stelax contains the active ingredient baclofen. Stelax belongs to a group of medicines called muscle relaxants.

Stelax is used to reduce the stiffness or spasms in your muscles to help make you more mobile and able to manage your daily activities. These spasms happen in various illnesses such as multiple sclerosis and diseases or injuries of the spinal cord.

2. What should I know before I use Stelax?

Warnings

Do not use Stelax if:

you are allergic to baclofen, or any of the ingredients listed at the end of this leaflet.

Always check the ingredients to make sure you can use this medicine.

Check with your doctor if you:

have any other medical conditions including mental illness, Parkinson's disease, seizures, stiffness and restriction of movement in a group of muscles, stomach ulcers, stroke or blood circulation problems, diabetes, a blood disorder known as porphyria, high blood pressure, difficulty urinating.
have problems with your heart, kidney, liver or lungs.
have a history of alcoholism, drink large amounts of alcohol, or have a history of drug abuse or dependence
have had thoughts of self-harm or and suicidal thoughts
take any medicines for any other condition
have any questions about why this medicine has been prescribed to you.

During treatment, you may be at risk of developing certain side effects. It is important you understand these risks and how to monitor for them. See additional information under Section 6. Are there any side effects?

Pregnancy and breastfeeding

Check with your doctor if you are pregnant or intend to become pregnant.

Talk to your doctor if you are breastfeeding or intend to breastfeed.

3. What if I am taking other medicines?

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

Some medicines may interfere with Stelax and affect how it works. These include:

any medicines that make you sleepy such as medicines used to help you sleep or calm you, pain relievers and medicines for cold or allergies
medicines used to treat mood disorders, including tricyclic antidepressants, lithium and monoamine oxidase inhibitors (MAOIs)
medicines used to treat diabetes
medicines for high blood pressure
medicines used to treat Parkinson's disease, including selegiline and levodopa and carbidopa.

Check with your doctor or pharmacist if you are not sure about what medicines, vitamins or supplements you are taking and if these affect Stelax.

4. How do I use Stelax?

How much to take

Your doctor will tell you how many tablets of Stelax to take.
Do not exceed the recommended dose prescribed by your doctor.
Treatment is usually started in hospital with small doses of Stelax. The dose is then gradually increased to an amount that works best for you.
If you are under the age of 16 or over 65, or you have kidney disease, your doctor may start you on a lower dose and increase slowly to prevent unwanted side effects.
Follow the instructions provided and use Stelax until your doctor tells you to stop.

When to take Stelax

Stelax is usually taken in 3 divided doses throughout the day.
Your doctor may tell you to take it more or less often, depending on your situation.

How to take Stelax

Swallow the tablets whole during meals with a glass of water or other liquid.

If you forget to take Stelax

If it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to.

Otherwise, take it as soon as you remember and then go back to taking it as you would normally.

Do not take a double dose to make up for the dose you missed.

If you use too much Stelax

If you think that you have used too much Stelax, you may need urgent medical attention.

You should immediately:

phone the Poisons Information Centre
(by calling 13 11 26), or
contact your doctor, or
go to the Emergency Department at your nearest hospital.

You should do this even if there are no signs of discomfort or poisoning.

Symptoms of overdose include:

Main symptoms such as drowsiness, breathing difficulties and being unconscious (coma).
Other symptoms such as feeling confused, hallucinations, agitation, convulsions, blurred vision, unusual low muscle tone, sudden and involuntary muscle spasm, poor or absent reflexes, high or low blood pressure, slow, fast or irregular heartbeat, low body temperature, nausea, vomiting, diarrhoea, excessive salivation, trouble breathing during sleep (sleep apnoea), severe muscle pain with fever and dark urine (rhabdomyolysis) and ringing in the ears.
If you have kidney disease and have accidentally taken more tablets than your doctor has prescribed, you may feel drowsy, confused, have hallucinations.

5. What should I know while using Stelax?

Things you should do

Keep all doctor's appointments, so that your progress can be checked.

Call your doctor straight away if you:

Become pregnant or think you might be pregnant.

Remind any doctor, dentist or pharmacist you visit that you are using Stelax.

Call your doctor straight away or go to a hospital if you have thoughts of harming or killing yourself.

Some people treated with Stelax have had suicidal thoughts. Ask a relative or close friend to tell you if they are worried about any changes in your behaviour.

Things you should not do

Do not stop using this medicine suddenly unless your doctor tells you to.
Do not use this medicine to treat any other problems unless your doctor tells you to.
Do not give this medicine to anyone else. Even if they have the same condition as you.

Driving or using machines

Be careful before you drive or use any machines or tools until you know how Stelax affects you.

Stelax may cause sleepiness and decreased alertness in some people, especially when you start taking it.

Drinking alcohol

Tell your doctor if you drink alcohol.

Alcohol may make you feel more sleepy when taking Stelax.

Looking after your medicine

Keep your tablets in the original container until it is time to take them.

Follow the instructions in the carton on how to take care of your medicine properly.

Store it in a cool dry place away from moisture, heat or sunlight; for example, do not store it:

in the bathroom or near a sink, or
in the car or on window sills.

Keep it where young children cannot reach it.

When to discard your medicine

If your doctor tells you to stop taking Stelax or the expiry date on the medicine has passed, ask your pharmacist what to do with any tablets you have left over.

Getting rid of any unwanted medicine

If you no longer need to use this medicine or it is out of date, take it to any pharmacy for safe disposal.

Do not use this medicine after the expiry date.

6. Are there any side effects?

All medicines can have side effects. If you do experience any side effects, most of them are minor and temporary. However, some side effects may need medical attention.

Side effects happen mainly at the start of treatment with Stelax or if the dose is too high or increased too quickly. Your doctor will adjust your dose if necessary.

See the information below and, if you need to, ask your doctor or pharmacist if you have any further questions about side effects.

Less serious side effects

Less serious side effects

What to do

Brains and nerves:

daytime sleepiness or drowsiness
lack of energy, tiredness
dizziness or light-headedness
spinning sensation (vertigo)
mental confusion
headache
difficulty sleeping or nightmares
change in sense of taste
blurred or double vision
ringing in the ears

Airways:

stuffy or blocked nose
dry mouth

Stomach Problems:

nausea (feeling sick), retching or vomiting
constipation, stomach cramps or diarrhoea
loss of appetite

General Problems:

numbness or tingling in hands and feet
muscle weakness, spasms or pain
problems with coordination and balance
difficulty in speaking
swelling of the ankles due to fluid build-up
frequent urination or bed wetting
excessive sweating
weight gain
impotence or inability to ejaculate
increased blood sugar
feeling cold

Speak to your doctor if you have any of these less serious side effects and they worry you.
If these side effects become severe, tell your doctor, pharmacist or healthcare provider.

Serious side effects

Serious side effects

What to do

Skin or Muscle Problems:

signs of allergy such as rash, itching or hives on the skin; swelling of the face, lips, tongue or other parts of the body; shortness of breath or wheezing
uncontrollable muscle spasms affecting the eyes, head, neck or body

Chest Problems:

slow or difficulty breathing
irregular heart beat (fast or slow)
chest pain

Neurological Problems:

fainting or seizures (fits)
depression or other severe mood, behaviour or mental changes
hallucinations (hearing or seeing things that are not there)
thoughts of suicide
anxiety, confusion, paranoia and other mental problems following sudden discontinuation of the medicine (drug withdrawal syndrome).

Other Problems:

being unable to urinate or pain when urinating; blood in the urine

Call your doctor straight away or go straight to the Emergency Department at your nearest hospital if you notice any of these serious side effects.

Tell your doctor or pharmacist if you notice anything else that may be making you feel unwell.

Other side effects not listed here may occur in some people.

Reporting side effects

After you have received medical advice for any side effects you experience, you can report side effects to the Therapeutic Goods Administration online at www.tga.gov.au/reporting-problems. By reporting side effects, you can help provide more information on the safety of this medicine.

Always make sure you speak to your doctor or pharmacist before you decide to stop taking any of your medicines.

7. Product details

This medicine is only available with a doctor's prescription.

What Stelax contains

Active ingredient (main ingredient)	Baclofen
Other ingredients (inactive ingredients)	Microcrystalline cellulose Maize starch Povidone Colloidal anhydrous silica Magnesium stearate
Potential allergens	None

The tablets are gluten free.

Do not take this medicine if you are allergic to any of these ingredients.

What Stelax looks like

Stelax 10 is a round off-white tablet marked BL│10 on one side, and plain on the other. Bottle of 100 tablets (Aust R 92251).

Stelax 25 is a round off-white tablet marked BL│25 on one side, and plain on the other. Bottle of 100 tablets (Aust R 92252).

Who distributes Stelax

Stelax is supplied in Australia by:

Arrotex Pharmaceuticals Pty Ltd
15-17 Chapel Street
Cremorne VIC 3121
www.arrotex.com.au

This leaflet was prepared in September 2023.

Published by MIMS November 2023

BRAND INFORMATION

Brand name

Stelax

Active ingredient

Baclofen

Schedule

1 Name of Medicine

Baclofen.

2 Qualitative and Quantitative Composition

Stelax tablets come in two strengths and contain either 10 mg or 25 mg of baclofen.
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Stelax 10.

Round, off-white tablet, marked BL/10 on one side and plain on the other.

Stelax 25.

Round, off-white tablet, marked BL/25 on one side and plain on the other.

4 Clinical Particulars

4.1 Therapeutic Indications

Suppression of voluntary muscle spasm in: multiple sclerosis;
spinal lesions of traumatic, infectious, degenerative, neoplastic and unknown origin, causing: skeletal hypertonus, spastic dyssynergic bladder dysfunction.
Not recommended in Parkinson's disease or spasticity arising from strokes, cerebral palsy or rheumatoid disorders.

4.2 Dose and Method of Administration

Treatment with baclofen should always be started in hospital, using small doses which are then gradually increased stepwise. The lowest dose compatible with an optimal response is recommended. The optimum daily dosage should be individually adapted to each patient's requirements so that clonus, flexor and extensor spasms, and spasticity are reduced, at the same time retaining enough muscle tone to permit active movements and avoiding adverse effects as far as possible.
In order to prevent excessive weakness and falling, baclofen should be used with caution when spasticity is needed to sustain upright posture and balance in locomotion or whenever spasticity is used to maintain function. It may be important to maintain some degree of muscle tone and allow occasional spasms to help support circulatory function.
Abrupt discontinuation of treatment should be avoided (see Section 4.4 Special Warnings and Precautions for Use).
In adults baclofen should be given in at least three divided doses daily.

Dosage regimen.

As a rule, treatment should be started with a dose of 5 mg three times daily, subsequently increased at 3-day intervals by 5 mg three times daily (i.e. the dosage regimen is 5 mg three times a day for 3 days, then 10 mg three times a day for 3 days, etc.) until the optimum response has been attained. In certain patients reacting sensitively to drugs, it may be advisable to begin with a lower daily dose (5 mg or 10 mg), increased by smaller steps at longer intervals (see Section 4.4 Special Warnings and Precautions for Use). The optimum dosage generally ranges from 30 mg to 75 mg daily, although occasionally in hospitalised patients daily doses up to 100 mg may be necessary.
If no benefit is apparent within 6 to 8 weeks of achieving the maximum dosage, a decision should be taken whether or not to continue treatment with baclofen.
Discontinuation of the treatment should always be gradual by successively reducing the dosage over a period of approximately 1 to 2 weeks, except in overdose-related emergencies, or where serious adverse effects have occurred (see Section 4.4 Special Warnings and Precautions for Use).

Special populations.

Renal impairment.

In patients with impaired renal function or undergoing chronic haemodialysis, low doses (i.e. approx. 5 mg daily) should be used. These patients should be closely monitored for prompt diagnosis of early signs and/or symptoms of toxicity (e.g. somnolence, lethargy) (see Section 4.4 Special Warnings and Precautions for Use; Section 4.9 Overdose). Signs and symptoms of overdosage have been reported with doses at and above 5 mg daily in this setting (see Section 4.9 Overdose).

Hepatic impairment.

No studies have been performed in patients with hepatic impairment under baclofen therapy. Baclofen should be prescribed with caution in patients with hepatic impairment (see Section 4.4 Special Warnings and Precautions for Use).

Elderly patients (aged 65 years and above).

Since unwanted effects are more likely to occur in elderly patients (due to increased risk of renal function impairment and CNS toxicity), a very cautious dosage schedule should be adopted and the patient kept under appropriate surveillance.
Toxicity due to baclofen may be taken for uraemic encephalopathy.

Paediatric patients.

Baclofen should be given with extreme caution to children under 16 years, as only limited data are available. Baclofen tablets are not suitable for use in children with a body weight below 33 kg.

Method of administration.

Baclofen should be taken during meals with a little liquid.

Monitoring advice.

Since in rare instances elevated AST, alkaline phosphatase or glucose levels in the serum have been recorded, appropriate laboratory tests should be performed periodically in patients with liver diseases or diabetes mellitus, in order to ensure that no drug induced changes in these underlying diseases have occurred.
Careful monitoring of respiratory and cardiovascular function is essential especially in patients with cardiopulmonary disease and respiratory muscle weakness.

4.3 Contraindications

Known hypersensitivity to baclofen or to any of the components of the formulation.

4.4 Special Warnings and Precautions for Use

Psychiatric and nervous system disorders.

Patients suffering not only from spasticity but also from psychotic disorders, schizophrenia, depressive or manic disorders or confusional states should be treated cautiously with baclofen and kept under careful surveillance, because exacerbations of these conditions may occur.
Suicide and suicide-related events have been reported in patients treated with baclofen. In most cases, the patients had additional risk factors associated with an increased risk of suicide including alcohol use disorder, depression and/or a history of previous suicide attempts. Close supervision of patients with additional risk factors for suicide should accompany drug therapy. Patients (and caregivers of patients) should be alerted about the need to monitor for clinical worsening, suicidal behaviour or thoughts or unusual changes in behaviour and to seek medical advice immediately if these symptoms present.
Cases of misuse, abuse and dependence have been reported with baclofen. Caution should be exercised in patients with a history of substance abuse and the patient should be monitored for symptoms of baclofen misuse, abuse or dependence e.g. dose escalation, drug-seeking behaviour, development of tolerance.

Epilepsy or other potential convulsive conditions.

Caution is needed in patients with epilepsy or other convulsive conditions, cortical or subcortical brain damage or significant EEG abnormalities, since ingestion of baclofen may cause deterioration of seizure control and EEG changes and may precipitate convulsions. In patients with epilepsy and muscle spasticity, baclofen can be employed under appropriate supervision, provided adequate anticonvulsive therapy is continued.
Lowering of the convulsion threshold may occur and seizures have been reported occasionally after cessation of baclofen or with overdosage.

Patients with other concomitant conditions.

Baclofen should be used with caution in patients with:
peptic ulcers or with a history of peptic ulcers;
cerebrovascular diseases or respiratory, hepatic or renal failure (due to increased risk of central nervous system, respiratory and cardiovascular depression);
porphyria;
a history of alcoholism;
diabetes mellitus (baclofen may increase blood glucose concentrations);
hypertension (see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions).
Since unwanted effects are more likely to occur, a cautious dosage schedule should be adopted in elderly and patients with spasticity. Baclofen is not recommended in Parkinson's disease or spasticity arising from strokes, cerebral palsy or rheumatoid disorders.

Changes in muscle tone.

Baclofen should be used with caution in patients who use spasticity to maintain upright posture and balance in moving. If an undesirable degree of muscular hypotonia occurs, making it more difficult for patients to walk or fend for themselves, this can usually be relieved by adjusting the dosage (i.e. by reducing the doses given during the day and possibly increasing the evening dose).
During treatment with baclofen, neurogenic disturbances affecting emptying of the bladder may improve, whereas in patients with pre-existing sphincter hypertonia, acute retention of urine may occur. The drug should, therefore, be used with caution in such cases.

Abrupt discontinuation.

Anxiety and confusional states, delirium, hallucinations, psychotic disorders, mania or paranoid states, convulsions (status epilepticus), dyskinesia, tachycardia, hyperthermia and, as a rebound phenomenon - temporary aggravation of spasticity have been reported upon the abrupt withdrawal of baclofen, especially after long-term medication.
Drug withdrawal reactions including postnatal convulsions in neonates have been reported after intrauterine exposure to oral baclofen. (See Section 4.6 Fertility, Pregnancy and Lactation, Use in pregnancy.)
For the intrathecal formulation of baclofen, it has been reported that clinical characteristics of withdrawal may resemble autonomic dysreflexia, infection (sepsis), malignant hyperthermia, neuroleptic-malignant syndrome, or other conditions associated with a hypermetabolic state or widespread rhabdomyolysis.
Except in overdose related emergencies or where serious adverse effects have occurred, treatment should, therefore, always be gradually withdrawn by successive dosage reduction over a period of approx. 1 to 2 weeks.
If withdrawal symptoms occur, restarting baclofen therapy and withdrawing over a longer period may help to resolve withdrawal problems.

Switching from oral to intrathecal baclofen and vice versa.

An attempt should be made to discontinue concomitant antispastic medication to avoid possible overdose or adverse drug interactions. This should preferably be done before switching from oral to intrathecal baclofen or vice versa and requires careful monitoring by the doctor. Abrupt reduction or discontinuation of concomitant antispastics during chronic therapy with baclofen should be avoided.

Posture and balance.

Baclofen should be used with caution when spasticity is needed to sustain upright posture and balance in locomotion (see Section 4.2 Dose and Method of Administration).

Use in hepatic impairment.

Because baclofen is partially metabolised in the liver, patients with impaired liver function should be periodically monitored with laboratory tests (see Section 4.2 Dose and Method of Administration).

Use in renal impairment.

Since baclofen is largely eliminated by the kidneys, a dosage reduction is advised to avoid drug accumulation. Baclofen should be used with caution in patients with renal impairment and should be administered to end stage renal failure patients only if the expected benefit outweighs the potential risk (see Section 4.2 Dose and Method of Administration, Renal impairment).
Neurological signs and symptoms of overdose including clinical manifestations of toxic encephalopathy (e.g. confusion, somnolence, hallucination) have been observed in patients with renal impairment taking baclofen at doses at and above 5 mg daily. Patients with renal impairment should be closely monitored for prompt diagnosis of early signs and symptoms of toxicity (see Section 4.9 Overdose).
Particular caution is required when combining baclofen to drugs or medicinal products that can significantly impact renal function. Renal function shall be closely monitored and baclofen daily dosage adjusted accordingly to prevent baclofen toxicity.
Besides discontinuing treatment, unscheduled haemodialysis might be considered as a treatment alternative in patients with severe baclofen toxicity. Haemodialysis effectively removes baclofen from the body, alleviates clinical symptoms of overdose and shortens the recovery time in these patients.

Use in the elderly.

Paediatric use.

Baclofen should be given with extreme caution to children under 16 years of age, as only limited data are available. Baclofen tablets are not suitable for use in children with a body weight below 33 kg.

Effects on laboratory tests.

No data available.

4.5 Interactions with Other Medicines and Other Forms of Interactions

Levodopa/dopa decarboxylase (DDC) inhibitor (carbidopa).

In patients with Parkinson's disease receiving treatment with baclofen and levodopa (alone or in combination with DDC inhibitor, carbidopa), there have been reports of mental confusion, hallucinations, headaches, nausea and agitation. Worsening of the symptoms of Parkinsonism has also been reported. Hence, caution should be exercised during concomitant administration of baclofen and levodopa/carbidopa.

Drugs causing central nervous system (CNS) depression.

Increased sedation may occur when baclofen is taken concomitantly with other drugs causing CNS depression including other muscle relaxants (such as tizanidine), with synthetic opiates or with alcohol (see Section 4.4 Special Warnings and Precautions for Use). The risk of respiratory depression is also increased. In addition, hypotension has been reported with concomitant use of morphine and intrathecal baclofen. Careful monitoring of respiratory and cardiovascular functions is essential, especially in patients with cardiopulmonary disease and respiratory muscle weakness.

Antidepressants.

During concurrent treatment with tricyclic antidepressants, the effect of baclofen may be potentiated, resulting in pronounced muscular hypotonia.

Lithium.

Concurrent use of oral baclofen and lithium resulted in aggravated hyperkinetic symptoms. Thus, caution should be exercised when baclofen is used concomitantly with lithium.

Antihypertensives.

Since concomitant treatment with antihypertensives is likely to enhance the fall in blood pressure, the dosage of antihypertensive medication should be adjusted accordingly.

Agents reducing renal function.

Drugs or medicinal products that can significantly impact renal function may reduce baclofen excretion leading to toxic effects (see Section 4.4 Special Warnings and Precautions for Use, Use in renal impairment).

Others.

Concurrent use of baclofen with monoamine oxidase (MAO) inhibitors may result in increased CNS-depressant and hypotensive effects. Caution is recommended and dosage of one or both agents may require reduction.
Since baclofen may increase blood glucose concentrations, dosage adjustments of insulin and/or oral hypoglycaemic agents may be necessary during and after concurrent therapy.
Studies in rats indicate that the agonistic effects of baclofen on gastric acid secretion are potentiated by diazepam.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

Data not available.
(Category B3)

Risk summary.

There are no adequate and well-controlled studies in pregnant women. Animal data showed that baclofen crosses the placental barrier. Therefore, baclofen should not be used during pregnancy unless the expected benefit outweighs the potential risk to the foetus.
Drug withdrawal reactions including postnatal convulsions in neonates following intra-uterine exposure to oral baclofen, have been reported. In one suspected case of postnatal baclofen withdrawal, the convulsions were refractory to various anticonvulsants, but responsive to the administration of baclofen to the affected neonate (see Section 4.4 Special Warnings and Precautions for Use, Abrupt discontinuation).
Studies in lactating women are limited to one (1) patient. In this particular case, available evidence suggests that baclofen is found in quantities so small that undesirable effects in the infant would have been unlikely.

4.7 Effects on Ability to Drive and Use Machines

Baclofen may be associated with adverse effects such as dizziness, sedation, somnolence and visual impairment (see Section 4.8 Adverse Effects (Undesirable Effects)) which may impair the patient's reaction. Patients experiencing these adverse reactions should be advised to refrain from driving or using machines.
The patient's ability to react may be adversely affected by sedation and decreased alertness caused by baclofen. Patients should, therefore, exercise due caution when driving a vehicle or operating machinery.

4.8 Adverse Effects (Undesirable Effects)

Adverse effects occur mainly at the start of treatment (e.g. sedation, somnolence), if the dosage is increased too rapidly, if large doses are employed or if the patient is elderly. They are often transitory and can be attenuated or eliminated by reducing the dosage. They may necessitate withdrawal of the medication. In patients with a history of psychiatric illness, cortical or organic brain disorders, or with cerebrovascular disorders (e.g. stroke), as well as in elderly patients, adverse reactions may be more serious.
It is often difficult to distinguish whether some of these are drug effects or manifestations of the diseases under treatment. Psychiatric manifestations can occur in acute or chronic toxicity due to baclofen.
Lowering of the convulsion threshold and convulsions may occur, particularly in epileptic patients (see Section 4.4 Special Warnings and Precautions for Use).
Certain patients have shown increased muscle spasticity as a paradoxical reaction to the medication.
Adverse reactions are ranked under heading of frequency, the most frequent first, using the following convention: very common (≥ 1/10); common (≥ 1/100, < 1/10); uncommon (≥ 1/1,000, < 1/100); rare (≥ 1/10,000, < 1/1,000); very rare (< 1/10,000); not known (cannot be estimated from the available data).

Nervous system disorders.

Very common: sedation, somnolence.
Common: respiratory depression, fatigue, confusional state, dizziness, personality changes, vertigo, headache, insomnia, euphoric mood, depression, muscle weakness, ataxia, tremor, hallucinations, nightmares, myalgia, nystagmus, dry mouth, tinnitus.
Rare: paraesthesia, dysarthria, dysgeusia, syncope, dyskinesia, coma, taste disturbances.
Very rare: hypothermia.
Not known: Cases of misuse, abuse and dependence have been reported with baclofen. Suicide and suicide-related events have been reported in patients treated with baclofen (see Section 4.4 Special Warnings and Precautions for Use, Psychiatric and nervous system disorders).

Eye disorders.

Common: accommodation disorder, visual impairment.

Cardiac disorders.

Common: cardiac output decreased.
Rare: arrhythmias, palpitations, chest pain.
Not known: bradycardia.

Vascular disorders.

Common: hypotension.
Rare: dyspnoea, ankle oedema.

Gastrointestinal disorders.

Very common: nausea (particularly at the start of treatment).
Common: gastrointestinal disorder, retching, vomiting, constipation, diarrhoea.
Rare: colicky abdominal pain, anorexia.

Hepatobiliary disorders.

Rare: hepatic function abnormal.

Skin and subcutaneous tissue disorders.

Common: hyperhidrosis, rash, pruritus.
Not known: urticaria.

Renal and urinary disorders.

Common: pollakiuria, enuresis, dysuria.
Rare: urinary retention, nocturia, haematuria.

Reproductive system and breast disorders.

Rare: erectile dysfunction, inability to ejaculate.

General disorders and administration site conditions.

Very rare: hypothermia.
Not known: drug withdrawal syndrome*.

Investigations.

Not known: blood glucose increase.

Miscellaneous.

Rare: nasal congestion, weight gain.
*Drug withdrawal syndrome including postnatal convulsions has also been reported after intra-uterine exposure to oral baclofen.

Reporting suspected adverse effects.

Reporting suspected adverse reactions after registration of the baclofen is important. It allows continued monitoring of the benefit-risk balance of baclofen. Healthcare professionals are asked to report any suspected adverse reactions at https://www.tga.gov.au/reporting-problems.

4.9 Overdose

Signs and symptoms.

Prominent features are signs of central nervous depression: somnolence, depressed level of consciousness, respiratory depression due to absent respiratory movement, coma.
Also liable to occur are: confusion, hallucinations, agitation, abnormal electroencephalogram (burst suppression pattern and triphasic waves), accommodation disorders, impaired pupillary reflex, generalised muscular hypotonia, myoclonus, hyporeflexia or areflexia, convulsions, peripheral vasodilatation, hypotension or hypertension, bradycardia, tachycardia or cardiac arrhythmias, hypothermia, nausea, vomiting, diarrhoea, salivary hypersecretion, increased hepatic enzymes, sleep apnoea, rhabdomyolysis, tinnitus.
A deterioration in the condition may occur if various substances or drugs acting on the central nervous system (e.g. alcohol, diazepam, tricyclic antidepressants) have been taken at the same time.
Adult patients have ingested up to 1125 mg of baclofen and survived. Ingestion of 1250 to 2500 mg by one patient was fatal. Serious poisoning has occurred with doses of 150 and 300 mg in adults.

Treatment.

No specific antidote is known.
Supportive measures and symptomatic treatment should be given for complications such as hypotension, hypertension, convulsions, gastrointestinal disturbances, and respiratory or cardiovascular depression.
Symptomatic treatment should include the following:
Elimination of the drug from the gastrointestinal tract, e.g. administration of activated charcoal; if necessary, saline laxatives.
Since the drug is excreted chiefly via the kidneys, generous quantities of fluid should be given, possibly together with a diuretic.
Measures in support of cardiovascular functions.
In the case of respiratory muscle weakness, administration of artificial respiration.
In the event of convulsions, diazepam should be administered cautiously i.v., paying attention to increased muscle relaxation and possible respiratory insufficiency, if the patient is not already being artificially ventilated.
Haemodialysis (sometimes unscheduled) may be useful in severe poisoning associated with renal failure (see Section 4.4 Special Warnings and Precautions for Use).
For information on the management of overdose, contact the Poisons Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Baclofen is an effective antispastic agent with a spinal site of action. Its mechanism of action and pharmacological properties are different from those of other antispastic agents.
Baclofen also has central sites of action given the adverse event profile and general CNS depressant properties.
Baclofen depresses monosynaptic and polysynaptic reflex transmission, probably by various actions, including stimulation of GABA_β-receptors. This stimulation in turn inhibits the release of excitatory amino acids (glutamate and aspartate) in guinea pig preparations. Neuromuscular transmission is not affected by baclofen.
Baclofen exerts an antinociceptive effect. The clinical significance of this awaits clarification. In neurological diseases associated with spasm of the skeletal muscles, the clinical effects of baclofen take the form of a beneficial action on reflex muscle contractions and of marked relief from painful spasm, automatism and clonus. Baclofen, where indicated, improves the patient's mobility, making for greater independence and facilitating passive and active physiotherapy. Baclofen stimulates gastric acid secretion.

Clinical trials.

No data available.

5.2 Pharmacokinetic Properties

Absorption.

Baclofen is rapidly and completely absorbed from the gastrointestinal tract. Maximum concentrations of unchanged drug are attained in plasma in 2 to 4 hours after an oral dose. The bioavailability of oral baclofen is 70 to 80%.
Following oral administration of a single dose of 40 mg baclofen, peak serum concentrations of 500 to 600 nanogram/mL are reached. The serum concentration remains above 200 nanogram/mL for 8 hours. The onset of action is highly variable and may range from hours to weeks.

Distribution.

The distribution volume of baclofen amounts to 0.7 L/kg. In cerebrospinal fluid, the active substance attains concentrations approx. 8.5 times lower than in the plasma.
Baclofen is bound to plasma proteins to the extent of about 30%.

Metabolism.

About 15% of a dose of baclofen is metabolised in the liver. Deamination yields the main metabolite, beta-chlorophenyl-gamma-hydroxybutyric acid, which is pharmacologically inactive.

Excretion.

Approximately 70% of baclofen is eliminated in the urine in unchanged form. The plasma elimination half-life of baclofen averages 4 to 7 hours. Within 72 hours, approx. 75% of the dose is excreted via the kidneys, approx. 5% of this quantity being in the form of metabolites. The remainder of the dose, including 5% as metabolites, is excreted in the faeces.

5.3 Preclinical Safety Data

Genotoxicity.

Baclofen did not induce mutations in bacterial or mammalian cells in vitro, lacked DNA damaging activity in the sister chromatid exchange assay and had no clastogenic activity in the nuclear anomaly test.

Animal data.

In two teratogenic studies in pregnant rats, baclofen has been shown to increase the incidence of omphalocoeles (ventral hernias) in foetuses at a dose of 20 mg/kg/day, which is maternotoxic. The relevance of this finding to humans is unknown. At the same dose there was also an increased incidence of incomplete sternebral ossification in the foetuses.
In mice, no teratogenic effects were observed at a dose of 81.5 mg/kg/day given via the diet or up to 40 mg/kg/day given by gavage. At 40 mg/kg/day by gavage, a delay in foetal growth was associated with maternal anorexia. The lack of maternotoxicity seen in the dietary study suggests that the dose used was inadequate.
In pregnant rabbits, oral doses up to 10 mg/kg/day were manifested as a sedative effect. Skeletal examination of foetuses revealed a marked increase in the absence of ossification of the phalangeal nuclei of forelimbs and hind limbs.

Carcinogenicity.

A two-year carcinogenicity study in rats found no evidence that baclofen had carcinogenic potential at oral doses up to 100 mg/kg/day. An apparently dose related increase in the incidence of ovarian cysts and enlarged and/or haemorrhagic adrenals at the highest two doses (50 and 100 mg/kg/day) was observed in female rats. The clinical relevance of these findings is not known.
Ovarian cysts have been found by palpation in about 5% of the multiple sclerosis patients who were treated with oral baclofen for up to one year. In most cases these cysts disappeared spontaneously while patients continued to receive the drug. Ovarian cysts are known to occur spontaneously in a proportion of the normal female population.

6 Pharmaceutical Particulars

6.1 List of Excipients

The tablets also contain the following excipients: microcrystalline cellulose, maize starch, povidone, colloidal anhydrous silica and magnesium stearate. The tablets are gluten free.
See Section 2 Qualitative and Quantitative Composition.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of this medicine.

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Store below 25°C.

6.5 Nature and Contents of Container

Stelax 10.

Supplied in bottles of 100 tablets.

Stelax 25.

Supplied in bottles and blisters* of 100 tablets.
*Not marketed.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of by taking to your local pharmacy.

6.7 Physicochemical Properties

Baclofen is a white or almost white, odourless or practically odourless, crystalline powder. It is slightly soluble in water, very slightly soluble in methanol and insoluble in chloroform.

Chemical structure.

The chemical name for baclofen is (RS)-4-amino-3-(4-chlorophenyl) butanoic acid.
It is a derivative of gamma-aminobutyric acid (GABA).
Baclofen structural formula is:

C₁₀H₁₂ClNO₂. Molecular weight: 213.67.

CAS number.

Cas No.: 1134-47-0.

7 Medicine Schedule (Poisons Standard)

S4 - Prescription only medicine.

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Baclofen

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Stelax 10 mg

Stelax 25 mg