SUMMARY CMI

Dantrium^® Capsules

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 taking Dantrium Capsules?

Dantrium contains an active ingredient dantrolene sodium hemiheptahydrate. It is used to relax muscles which are in spasm as a result of spinal cord injury, stroke, cerebral palsy or multiple sclerosis. It is of particular help to patients whose rehabilitation is being slowed down by muscle spasm. For more information, see Section 1. Why am I taking Dantrium Capsules? in the full CMI.

2. What should I know before I take Dantrium Capsules?

Do not take Dantrium capsules if you have ever had an allergic reaction to any medicine containing dantrolene sodium hemiheptahydrate or any of the ingredients listed at the end of this leaflet; are lactose intolerant; have liver disease such as hepatitis and cirrhosis; or your muscle spasms allow you to keep an upright position, to balance during movement or for better physical function. Talk to your doctor if you have liver, heart or kidney problems; breathing difficulty; are pregnant, or plan to become pregnant or are breastfeeding.

For more information, see Section 2. What should I know before I take Dantrium Capsules? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with Dantrium 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 take Dantrium Capsules?

Your doctor will decide how much Dantrium you should take each day and how long your treatment with Dantrium should continue. More instructions can be found in Section 4. How do I take Dantrium Capsules? in the full CMI.

5. What should I know while taking Dantrium Capsules?

For more information, see Section 5. What should I know while taking Dantrium Capsules? in the full CMI.

6. Are there any side effects?

Side effects of this medicine may include drowsiness; dizziness; weakness; fatigue; diarrhoea; constipation; loss of appetite; difficulty swallowing; stomach cramps/pain; indigestion; dry mouth; excessive saliva; vomiting; nausea; alteration of taste; swelling of the face, lips, tongue or other parts of the body; shortness of breath; wheezing; trouble breathing; chest pain; fits; speech problems; headache; light-headedness; visual problems; trouble sleeping; depression; confusion; rashes; bleeding or bruising more easily; sweating; backache; muscle pain; excessive tearing; chill; fever; frequent urination; abnormal colouration of the urine; incontinence; difficulty passing urine; erection problem; abnormal hair growth.

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

Dantrium^® Capsules

Active ingredient(s): Dantrolene sodium hemiheptahydrate

Consumer Medicine Information (CMI)

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

Where to find information in this leaflet:

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

1. Why am I taking Dantrium Capsules?

Dantrium capsules contain the active ingredient dantrolene sodium hemiheptahydrate. The medicine is used to relax muscles which are in spasm as a result of spinal cord injury, stroke, cerebral palsy or multiple sclerosis. It is of particular help to those patients whose rehabilitation is being slowed down by muscle spasm.

Your doctor may have prescribed it for another reason.

Ask your doctor if you have any questions about why Dantrium has been prescribed for you.

2. What should I know before I take Dantrium Capsules?

Warnings

Do not take Dantrium if you are allergic to:

• any medicine containing dantrolene sodium hemiheptahydrate
• lactose
• any of the ingredients listed at the end of this leaflet.

Symptoms of an allergic reaction may include shortness of breath, wheezing or difficulty breathing; swelling of the face, lips, tongue or other parts of the body; rash, itching or hives on the skin.

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

• liver disease such as hepatitis and cirrhosis
• where your muscle spasms are used to allow you to keep an upright position, to balance during movement or for better physical function.

Do not take Dantrium if:

• the packaging is torn or shows signs of tampering
• the expiry date printed on the pack has passed.

Tell your doctor if you have allergies to any other medicines, foods, preservatives or dyes.

Tell your doctor if you have or have had any of the following medical conditions:

• you have liver problems.

It is essential to have your liver checked by your doctor before taking Dantrium, to determine if you have any existing problems with your liver.

• you have problems with your lungs and breathing
• you have heart problems
• you have kidney problems.

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. Your doctor can discuss with you the risks and benefits involved.

Dantrium should not be used while breastfeeding.

If you are not sure whether you should start taking this medicine, talk to your doctor.

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

3. What if I am taking other medicines?

Tell your doctor or pharmacist if you are taking any other medicines, including:

• all prescription medicines
• all medicines, vitamins, herbal supplements or natural therapies you buy without a prescription from a pharmacy, supermarket, naturopath or health food shop.

Some medicines may be affected by Dantrium or may affect how well it works. You may need different amounts of your medicines, or you may need to take different medicines. Your doctor will advise you.

Tell your doctor or pharmacist if you are taking any of the following:

• medicines containing oestrogen, which include oral contraceptives and medicines used to treat symptoms of menopause
• calcium channel blockers such as verapamil, used to treat high blood pressure
• other muscle relaxant medicines which work differently to Dantrium
• CNS depressants (medicines to reduce anxiety or help you sleep).

Your doctor and pharmacist have more information on medicines to be careful with or avoid while taking this medicine.

4. How do I take Dantrium Capsules?

Follow all directions given to you by your doctor or pharmacist carefully.

They may differ from the information contained in this leaflet.

How much to take

Your doctor will decide how much Dantrium you should take each day and how long your treatment with Dantrium should continue.

Take the capsules exactly as instructed by your doctor or pharmacist.

When to take

Your doctor will tell you how many times a day you should take Dantrium.

Always read the pharmacist's label to check the exact dose and how often to take it.

If you forget to take Dantrium

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 that you have missed.

If you are not sure whether to skip the dose, ask your doctor or pharmacist for advice.

If you take too much Dantrium

Immediately telephone your doctor, or the Australian Poisons Information Centre (telephone 131 126), or go to Accident and Emergency at your nearest hospital, if you think you or anyone else may have taken too much Dantrium.

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

You may need urgent medical attention.

5. What should I know while taking Dantrium Capsules?

Things you should do

Keep all your doctor's appointments so that your progress and health can be monitored.

Dantrium can cause damage to your liver, so your liver function needs to be checked regularly by your doctor to detect any abnormalities.

If you become pregnant while being treated with Dantrium, tell your doctor immediately.

If you are about to be started on any new medicine, tell your doctor and pharmacist that you are being treated with Dantrium.

Tell all doctors, dentists and pharmacists who are treating you that you are taking Dantrium.

Things you should not do

Do not take Dantrium to treat any other complaints unless your doctor tells you to.

Do not give your medicine to anyone else, even if they have the same condition as you.

Things to be careful of

Be careful of exposure to sunlight while being treated with Dantrium.

Dantrium may increase sensitivity of the skin to sun. Symptoms of sunburn (such as redness, itching, swelling or blistering) may occur more quickly than normal.

Driving or using machines

Do not drive or operate machinery while you are taking Dantrium capsules.

Dantrium causes drowsiness, dizziness and weakness in some people and therefore may affect alertness.

Drinking alcohol

Avoid drinking alcohol or taking medicines to reduce anxiety or help you sleep.

These may increase the drowsiness and dizziness effects of Dantrium and should be avoided.

Looking after your medicine

Keep Dantrium in its original packaging until it is time to use it. If you take Dantrium out of its packaging, it may not keep as well.

Keep your Dantrium in a cool, dry place where the temperature stays below 30°C.

Do not store Dantrium or any other medicine in the bathroom or near a sink. Do not leave it in the car or on a window sill.

Heat and dampness can destroy some medicines.

Keep it where young children cannot reach it.

A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.

When to discard your medicine

If your doctor tells you to stop taking this medicine, or it has passed its expiry date, take it to any pharmacy for safe disposal.

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.

See the information below. Ask your doctor or pharmacist if you have any questions about side effects.

Common side effects

Serious side effects

These are serious side effects. You may need urgent medical attention or hospitalisation. These side effects are rare.

Some of these side effects (for example certain liver conditions, and blood abnormalities) can only be found when your doctor does tests from time to time to check your progress.

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

What Dantrium Capsules contain

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

What Dantrium Capsules looks like

Dantrium 25 mg capsule (AUST R 42975): hard gelatin capsule with a tan opaque body and orange opaque cap, imprinted with "Dantrium" "25 mg" on the cap and "0149" "0030" and single coding bars on the body in black ink. Fill: deep orange cylindrical plug.

Dantrium 50 mg (AUST R 42976): hard gelatin capsule with a tan opaque body and orange opaque cap, imprinted with the logo "Dantrium" "50mg" on the cap and "0149" "0031" and single coding bars on the body in black ink. Fill: deep orange cylindrical plug.

Who distributes Dantrium Capsules

Pfizer Australia Pty Ltd
Sydney NSW
Toll Free Number: 1800 675 229
www.pfizermedicalinformation.com.au

This leaflet was prepared in November 2024.

^® Registered trademark

Published by MIMS January 2025

1 Name of Medicine

Dantrolene sodium hemiheptahydrate.

2 Qualitative and Quantitative Composition

25 mg capsule.

50 mg capsule.

Excipient(s) with known effect.

3 Pharmaceutical Form

25 mg capsule.

50 mg capsule.

4 Clinical Particulars

4.1 Therapeutic Indications

Dantrium is indicated in controlling the manifestations of clinical spasticity resulting from serious chronic disorders such as spinal cord injury, stroke, cerebral palsy, or multiple sclerosis. It is of particular benefit to the patient whose functional rehabilitation has been retarded by the sequelae of spasticity. Such patients must have presumably reversible spasticity where relief of spasticity will aid in restoring residual function. There is no evidence that patients with contractures will benefit. Dantrium is not indicated in the treatment of skeletal muscle spasm resulting from rheumatic disorders or electroconvulsive therapy.
If improvement occurs, it will ordinarily occur within the dosage titration schedule (see Section 4.2 Dose and Method of Administration), as manifested by a decrease in the severity of spasticity and the ability to resume a daily function not quite attainable without Dantrium.
Occasionally, subtle but meaningful improvements in spasticity may occur with Dantrium therapy. In such instances information regarding improvement should be solicited from the patient directly and from those who are in constant daily contact and attendance with the patient. Brief withdrawal of Dantrium for a period of 2 to 4 days will frequently demonstrate exacerbation of the manifestation of spasticity and may serve to confirm a clinical impression.
A decision to continue the administration of Dantrium on a long-term basis is justified if introduction of the drug into the patient's regimen produces a significant reduction in painful and/or disabling spasticity such as clonus, or permits a significant reduction in the intensity and/or degree of nursing care required, or rids the patient of an annoying manifestation of spasticity considered important by the patient themselves.

4.2 Dose and Method of Administration

Dosage.

Adults.

Children.

4.3 Contraindications

Active hepatic disease, such as acute hepatitis and active cirrhosis, is a contraindication for use of Dantrium. Dantrium is contraindicated where spasticity is utilised to sustain upright posture and balance in locomotion, or whenever spasticity is utilised to obtain or maintain increased function.

4.4 Special Warnings and Precautions for Use

If no observable benefit is derived from the administration of Dantrium after a total of 45 days, therapy should be discontinued. The lowest possible effective dose for the individual patient should be prescribed.

Hepatotoxicity.

Impaired pulmonary function.

Photosensitivity.

Neuroleptic malignant syndrome.

Long-term safety.

Use in hepatic impairment.

Use in renal impairment.

Use in the elderly.

Paediatric use.

Effects on laboratory tests.

4.5 Interactions with Other Medicines and Other Forms of Interactions

While a definite drug interaction with oestrogen therapy has not yet been established, caution should be observed if the two drugs are to be given concomitantly. Hepatotoxicity has occurred more often in women over 35 years of age receiving concomitant oestrogen therapy.
There are very rare reports of cardiovascular collapse in patients treated simultaneously with verapamil and dantrolene sodium hemiheptahydrate. The combination of therapeutic doses of intravenous dantrolene sodium hemiheptahydrate and verapamil in halothane/ α-chloralose anaesthetised swine has resulted in ventricular fibrillation and cardiovascular collapse in association with marked hyperkalaemia. Until the relevance of these findings to humans is established, the combination of dantrolene sodium hemiheptahydrate and calcium channel blockers, such as verapamil, is not recommended.
The effects of nondepolarising muscle relaxants may be potentiated in patients administered dantrolene.
Administration of Dantrium may potentiate vecuronium induced neuromuscular block.
Dantrolene causes dizziness, drowsiness, and weakness; alcohol and other CNS depressants such as sedatives and tranquilising agents may intensify this effect.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

4.7 Effects on Ability to Drive and Use Machines

Patients should be cautioned against driving a motor vehicle or participating in hazardous occupations while taking Dantrium. Dantrolene causes dizziness, drowsiness and weakness; alcohol and other CNS depressants may intensify this effect.

4.8 Adverse Effects (Undesirable Effects)

The most frequently occurring adverse effects of Dantrium have been drowsiness, dizziness, weakness, general malaise, fatigue, and diarrhoea. These effects have been experienced by approximately 20% of patients. They are generally transient, occurring early in treatment, and can often be obviated by beginning with a low dose and increasing dosage gradually until an optimal regimen is established. Diarrhoea may be severe and may necessitate temporary withdrawal of Dantrium therapy. If diarrhoea recurs upon readministration of Dantrium, therapy should probably be withdrawn permanently.
Other less frequent adverse effects, listed according to system are:

Gastrointestinal.

Haematologic.

Hepatobiliary.

Neurologic.

Cardiovascular.

Psychiatric.

Urogenital.

Integumentary.

Musculoskeletal.

Respiratory.

Special senses.

Hypersensitivity.

Other.

Reporting suspected adverse effects.

4.9 Overdose

Fatal poisoning with this agent is rare, and lethal doses are not established. There is no known set of symptoms with acute overdose. Signs and symptoms are likely to be an extension of those under Section 4.8 Adverse Effects (Undesirable Effects). The primary toxic effect is CNS depression and in severe cases coma. Respiratory depression may occur in patients with significant CNS depression. Total skeletal paralysis is unlikely in conscious patients. Symptoms that may occur include, but are not limited to, muscular weakness, alterations in the state of consciousness (e.g. lethargy, coma), vomiting, diarrhoea and crystalluria. Mild tachycardia and hypotension may develop. Oral dantrolene may cause lethargy, but is likely to resolve uneventfully.
Monitor and support respiratory and cardiovascular function.
Intravenous fluids should be administered in fairly large quantities to avert the possibility of crystalluria. Consider central venous pressure monitoring to guide further fluid therapy. Fluids and electrolytes should be monitored closely. Monitor patients with significant CNS depression for respiratory insufficiency and rhabdomyolysis.
Emesis is not recommended due to risk of CNS and respiratory depression.
Excretion of the active compounds is not known to be enhanced by fluid diuresis.
For information on the management of overdose, contact the Poison Information Centre on 13 11 126 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Clinical trials.

5.2 Pharmacokinetic Properties

The absorption of Dantrium after oral administration in humans is incomplete and slow, but consistent and dose related blood levels are obtained. The duration and intensity of skeletal muscle relaxation is related to the dosage and blood levels. The mean biological half-life of Dantrium in adults is 8.7 hours after a 100 mg dose. Specific metabolic pathways in the degradation and elimination of Dantrium in human subjects have been established. Metabolic patterns are similar in adults and children. In addition to the parent compound, dantrolene, which is found in measurable amounts in blood and urine, the major metabolites noted in body fluids are the 5-hydroxy analogue and the acetamido analogue.
Approximately 20 to 25% of an oral dose appears in the urine in the metabolised form and 1% or less is excreted unchanged. About 45 to 50% of the same oral dose appears in the bile. Since Dantrium is probably metabolised by hepatic microsomal enzymes, enhancement of its metabolism by other drugs is possible. However, neither phenobarbital nor diazepam appears to affect Dantrium metabolism.
Based on assays of whole blood and plasma, slightly greater amounts of dantrolene are associated with red blood cells than with the plasma fraction of blood. Significant amounts of dantrolene are bound to plasma proteins, mostly albumin, and this binding is readily reversible. Binding to plasma protein is not significantly altered by diazepam, diphenylhydantoin, or phenylbutazone. Binding to plasma proteins is reduced by warfarin and clofibrate and increased by tolbutamide.

5.3 Preclinical Safety Data

Genotoxicity.

Carcinogenicity.

6 Pharmaceutical Particulars

6.1 List of Excipients

Gelatin, iron oxide red, iron oxide yellow, lactose monohydrate, magnesium stearate, sodium lauryl sulfate, maize starch, sunset yellow FCF, purified talc, TekPrint SW-9008 black ink, TekPrint SW-9010 black ink, and titanium dioxide.

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 30°C.

6.5 Nature and Contents of Container

Dantrium capsules are available in HDPE bottles of 100.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of in accordance with local requirements.

6.7 Physicochemical Properties

Dantrolene sodium hemiheptahydrate is an orange powder, slightly soluble in water, but due to its slightly acidic nature the solubility increases somewhat in alkaline solution. The anhydrous salt has a molecular weight of 336. The hydrated salt contains approximately 15% water (3½ moles) and has a molecular weight of 399.
Dantrolene sodium hemiheptahydrate is 1-{[5-(p-nitrophenyl) furfurylidene]amino}hydantoin sodium hydrate. The chemical structure of hydrated dantrolene sodium is shown below.

Chemical structure.

CAS number.

7 Medicine Schedule (Poisons Standard)

Prescription Only Medicine (S4).

Summary Table of Changes