• Keep this leaflet. You may need to read it again.
• If you have any further questions, ask your doctor, pharmacist or nurse.
• This medicine has been prescribed for you only. Do not pass it on to others. It may harm them, even if their signs of illness are the same as yours.
• If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. See section 4.

1. What Dantrium Capsules are and what they are used for
2. What you need to know before you take Dantrium Capsules
3. How to take Dantrium Capsules
4. Possible side effects
5. How to store Dantrium Capsules
6. Contents of the pack and other information

• if you are allergic to dantrolene sodium 3.5 H2O, or any of the other ingredients of this medicine (listed in section 6),
• if you have liver disease,
  • in cases where abnormally increased muscle tension is required to improve function, posture or movement balance,
• if you have impaired lung function,
• if you have severe heart muscle damage,
• if you are pregnant or breast-feeding,
• If you are allergic (hypersensitive) to wheat, due to the presence of wheat starch.

Talk to your doctor or pharmacist before taking Dantrium.

Take special care with Dantrium

• if you suffer from amyotrophic lateral sclerosis (ALS, a disorder of the nervous system), if you have symptoms of bulbar paralysis (symptoms caused by damage to certain cranial nerves), as Dantrium can exacerbate symptoms of paralysis,
• if you have heart disease, particularly heart damage and/or heart arrhythmia. Your doctor will carefully monitor you for heart disease.

Before and during treatment with Dantrium your doctor will carry out regular blood tests to check your liver function. If the values are outside the normal range, treatment with Dantrium must be discontinued.

If you notice any signs that might indicate liver damage, such as unusual fatigue, light stools, itching all over the body, yellowing of the skin or eyes, loss of appetite, nausea and vomiting, you should seek medical attention immediately.

The risk of liver damage appears to be particularly high at daily doses of more than 300 mg, with prolonged treatment, in female patients over 30 years of age, with a history of liver damage and concomitant use of other medicines that can cause liver damage. Liver damage can be life-threatening, especially in the elderly.

If you suffer from multiple sclerosis, the risk of serious liver damage appears to be even higher.

Dantrium may cause the skin to become sensitive to light (photosensitisation), so you should protect yourself from strong sunlight during treatment.

Administration of Dantrium must be discontinued if patients have developed cardiac and pleural reactions with fluid accumulation (pleural or pericardial effusion or pleuropericarditis).

Doses of more than 200 mg dantrolene per day are more likely to cause side effects.

This medicine contains only very low levels of gluten (from wheat starch). It is regarded as ‘gluten-free’ and is very unlikely to cause problems if you have coeliac disease.

One Dantrium 25mg capsule contains no more than 3.8 micrograms of gluten.

One Dantrium 100mg capsule contains no more than 3.3 micrograms of gluten.

Dantrium can be used in children over 5 years of age under supervision from your doctor.

Dantrium should not be given to children under 5 years of age as there is insufficient experience with the use of Dantrium in this patient group to determine tolerability.

Tell your doctor or pharmacist if you are taking/using or have recently taken/used any other medicines, even if they are not prescription medications.

If taken at the same time as

• oestrogens (certain hormones) or other potentially liver-damaging substances there is an increased risk of liver damage,
• vecuronium (muscle relaxant drug) its effect can be amplified,
• metoclopramide (a medicine used to treat certain gastrointestinal disorders), the absorption of the active ingredient of Dantrium in the body may be increased, leading to an increase in the effect and side effects of dantrolene.

Simultaneous use of medicines that depress the central nervous system (sedatives, such as benzodiazepines, antihistamines) and alcohol is to be avoided as the side effects of Dantrium may be increased (in particular the central nervous system depressant effect and muscle weakness).

In patients predisposed to malignant hyperthermia (certain complications of anaesthesia) who received intravenous dantrolene, it has been observed that simultaneous administration of calcium antagonists and/or beta-blockers (antihypertensive/heart disease drugs) resulted in elevated potassium levels and cardiac insufficiency.

Do not drink alcohol while taking Dantrium.

Dantrium should not be used during pregnancy, as the safety of Dantrium for use during pregnancy has not been established.

The active substance of Dantrium passes into breast milk. Dantrium should not be used while breast-feeding, since adverse effects on the breastfed child cannot be excluded, particularly under long-term treatment with Dantrium. Breast-feeding must be discontinued if treatment is required while breast-feeding.

Ask your doctor or pharmacist for advice before taking/using any medicine.

You must not drive or operate machinery without consulting your doctor.

When Dantrium or other medicines that also affect the central nervous system are taken at the same time, central nervous system effects, such as drowsiness or confusion, can change the ability to react to such an extent that it reduces the ability to drive or operate tools and machines. This particularly applies at the start of treatment, when dosage is increased and when taken together with alcohol.

This medicine contains lactose and wheat starch. If you have been told by your doctor that you have an intolerance to some sugars, speak to your doctor before taking this medicine.

Tell your doctor immediately. He or she will take the necessary measures. Signs of overdose may include disorders of consciousness (e.g. lethargy, coma), muscle weakness, fatigue, dizziness, weakness, impaired vision, rapid heartbeat, itching, loss of appetite, nausea, vomiting, diarrhoea, light stools, yellowing of the skin or eyes.

Do not take a double dose to make up for an omitted dose. Take the same number of capsules as prescribed, when your next dose is due. If you are unsure what to do, please talk to your doctor.

If you temporarily want to stop treatment or stop it early, e.g. because the side effects appear too severe, please talk to your doctor first.

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

By reporting side effects, you can help provide more information on the safety of this medicine.

• The active substance is dantrolene sodium, 25 mg or 100 mg per capsule.
• The other ingredients are: lactose monohydrate, wheat starch, talcum and magnesium stearate (see section 2).
• The capsule shell of Dantrium 25mg and 100mg capsules contains gelatine and colouring agents titanium dioxide (E171), erythrosine (E127) and iron oxide (E172).

• Dantrium 25 mg Capsules: The capsules are light brown/orange. They are packed in blisters and available in packs of 100 hard capsules.
• Dantrium 100 mg Capsules: The capsules are orange/orange. They are packed in blisters and available in packs of 100 hard capsules.

Other sources of information

If you need further information on this leaflet in an alternative format please ring 0800 198 5000.