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Active substance(s): PRIMIDONE

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50mg and 250mg Tablets
Read all of this leaflet carefully before you start using this medicine.
Keep this leaflet. You may need to read it again.
If you have any further questions, ask your doctor or pharmacist.
This medicine has been prescribed for you. Do not pass it on to others. It may harm
them, even if their symptoms are the same as yours.
If any of the side effects gets serious, or if you notice any side effects not listed in this
leaflet, please tell your doctor or pharmacist.
In this leaflet:
What Mysoline is and what it is used for
Before you use Mysoline
How to use Mysoline
Possible side effects
How to store Mysoline
Further information
Mysoline contains primidone as the active ingredient; this belongs to a group of medicines
used to treat seizures.
Mysoline is used for the treatment of certain types of epilepsy, seizures (fits) or shaking attacks
(essential tremor).
Do not take Mysoline if you:
• are allergic (hypersensitive) to primidone, a substance called phenobarbitone, or to any
of the other ingredients of Mysoline (these are listed in Section 6: Further information).
• have porphyria (a rare inherited disorder of metabolism) or anyone in your family has
Take special care with Mysoline if you:
• have ever had problems with your breathing, kidneys or liver.
• are pregnant or are trying to become pregnant (see beneath for further information)
If you go into hospital, tell the medical staff that you are taking Mysoline.
A small number of people being treated with anti-epileptics such as primidone have had
thoughts of harming or killing themselves. If at any time you have these thoughts,
immediately contact your doctor.
Potentially life-threatening skin rashes (Stevens-Johnson syndrome, toxic epidermal
necrolysis) have been reported with the use of Mysoline, appearing initially as reddish targetlike spots or circular patches often with central blisters on the trunk.
Additional signs to look for include ulcers in the mouth, throat, nose, genitals and conjunctivitis
(red and swollen eyes).
These potentially life-threatening skin rashes are often accompanied by flu-like symptoms. The
rash may progress to widespread blistering or peeling of the skin.
The highest risk for occurrence of serious skin reactions is within the first weeks of treatment.

If you have developed Stevens-Johnson syndrome or toxic epidermal necrolysis with the use
of Mysoline or any other medicine containing phenobarbital, you must not be re-started on
these medicines at any time.
If you develop a rash or these skin symptoms, seek immediate advice from a doctor and
tell them that you are taking this medicine.
Taking other medicines
Please tell your doctor if you are taking or have recently taken any other medicines, including
medicines obtained without a prescription. This is important because some medicines may
affect the way Mysoline works, or Mysoline may affect the way other medicines work.
In particular, tell your doctor if you are taking any of the following:
• Other medicines used to treat epilepsy and other types of seizures (such as phenytoin,
felbamate, sodium valproate, carbamazepine, ethosuxamide, oxcarbazepine,
perampanel, stiripentol, tiagabine, topiramate, zonisamide)
• Anticoagulants to prevent blood clots (such as warfarin)
• Barbiturates (such as sleeping tablets)
• Methadone (used to treat severe pain, cough, or as a substitute for morphine addiction)
• Herbal remedies containing St John’s Wort
• Antibiotics (such as chloramphenicol, metronidazole, doxycycline)
• Antiviral medicines (such as nelfinavir)
• Asthma medicines (such as theophylline, montelukast)
• Hormone containing medicines (such as the oral contraceptive pill)
• Medicines used to treat high blood pressure or heart conditions (such as beta-blockers,
digitoxin, losartan, nimodipine, quinidine)
• Cyclosporin (used to prevent rejection of an organ transplant and also for other
diseases of the body’s immune system)
• Medicines used to treat mental health problems or depression (such as clozapine,
lamotrigine, mianserin, tricyclic antidepressants)
• Steroid-containing medicines
• Medicines used to treat cancer (such as cyclophosphamide, etoposide)
• Granisetron (used to treat severe nausea and vomiting)
• Medicines used during an anesthetic for surgery (such as rocuronium, vecuronium)
• Medicines containing morphine, or similar medicines called opiates.
Mysoline may increase the toxic effect on the liver of an overdose of paracetamol.
Taking Mysoline with food and drink
Alcohol can react with Mysoline. Ask your doctor for advice if you want to drink alcohol.
Pregnancy and breast-feeding
Ask your doctor for advice before taking any medicine.
The use of Mysoline in pregnancy is associated with an increased risk of abnormalities in
babies. Therefore, you must tell your doctor if you are pregnant, or trying to become pregnant
because Mysoline has the potential to harm your unborn child.
Pregnant women can have reduced folic acid in their blood whilst taking Mysoline. In addition,
the new born child may develop withdrawal symptoms if the mother has taken Mysoline in the
late stages of pregnancy. Blood clotting problems have occurred occasionally in children born
to women who were previously taking anticonvulsant drugs. Tell your doctor if you are breastfeeding because Mysoline may cause your baby to be very sleepy.

Driving and using machines
Mysoline can make you feel sleepy. If so, do not drive or operate machinery.
Always take Mysoline exactly as your doctor has told you. You should check with your doctor
or pharmacist if you are not sure.
Swallow the tablets whole with a drink of water.
Mysoline is normally taken twice a day. Try to take your tablets at the same time each day.
At first, your dose may be as little as 125mg (half a 250mg tablet). This will be adjusted by your
doctor until your condition is controlled. Typical maintenance doses are as follows:
Age group
Adults and children over 9 years
Children 6 to 9 years
Children 2 to 5 years
Children up to 2 years

Daily dose (milligrams)
750 to 1500
750 to 1000
500 to 750
250 to 500

Elderly / Patients with low physical strength
Lower doses may be prescribed.
Shaking attacks (Essential tremor)
Your starting dose may be 50mg. This will be adjusted by your doctor until your condition is
controlled. The maximum daily dose for shaking attacks (essential tremor) is 750 mg.
If you take more Mysoline than you should
If you take more than your normal dose, contact your doctor or nearest hospital.
If you forget to take Mysoline
If you miss a dose, take it as soon as you remember. Do not take a double dose to make up
for a forgotten tablet.
If you stop taking Mysoline
Do not stop taking your Mysoline, even if you are feeling well, unless your doctor tells you to.
You may have become dependent on Mysoline, and therefore you could get a withdrawal
reaction if you stop treatment too quickly. Mysoline treatment should be reduced gradually to
prevent this.
If you have any further questions on the use of this product, ask your doctor or
Like all medicines, Mysoline can cause side effects, although not everybody gets them.
When first taking Mysoline, drowsiness and lack of energy may occur; these usually pass.
There have been reports of bone disorders including osteopenia and osteoporosis (thinning of
the bone) and fractures. Check with your doctor or pharmacist if you are on long-term
antiepileptic medication, have a history of osteoporosis, or take steroids.

Common side effects (affecting fewer than 1 in every 10 people)
• disturbances of vision
• dizziness
• jerky movements
• rolling of the eyes
Uncommon side effects (affecting fewer than 1 in every 100 people)
• nausea and vomiting
• headache
• skin rash
Rare side effects (affecting fewer than 1 in every 1000 people)
• joint or bone pain
• changes in mood or behaviour.
• severe skin reactions affecting large portions of your body including redness, pain,
ulcers, blisters, shedding the outer layer of skin or involvement of lips or the lining of
the mouth, nostrils or ears (e.g. toxic epidermal necrolysis, Stevens-Johnson
• a disease called lupus erythematosus which causes inflammation of various parts of
the body including the skin, joints, lungs, kidneys, heart, and liver.
• development of Dupuytren’s contracture (a thickening of fibrous tissue in the palm of
the hand that causes one or more fingers to draw back).
• abnormalities of the blood cells; if you notice a pale appearance of your skin, abnormal
bleeding or tendency to bruising, fever or sore throat please consult your doctor.
• raised levels of enzymes in your liver.
Very rare (affecting fewer than 1 in every 10,000 people)
• Potentially life-threatening skin rashes (Stevens-Johnson syndrome, toxic epidermal
necrolysis) have been reported (see section 2).
Do not be alarmed by this list of possible events. You may not have any of them.
Reporting of side effects
If you get any side effects, talk to your doctor or pharmacist. This includes any possible side
effects not listed in this leaflet. You can also report side effects directly via the Yellow Card
Scheme (Website: By reporting side effects you can help
provide more information on the safety of this medicine.
Keep out of the reach and sight of children
Keep your tablets below 25°C.
Do not use Mysoline after the expiry date which is stated on the carton as {EXP MM/YYYY}.
The expiry date refers to the last day of that month.
Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist
how to dispose of medicines no longer required. These measures will help to protect the
What Mysoline contains

The active substance is primidone. Each tablet contains either 50 mg or 250 mg of primidone.
The other ingredients are carmellose calcium, gelatin, magnesium stearate, povidone K30 and
stearic acid, which are all typical ingredients used in tablet manufacture.
What Mysoline looks like and contents of the pack
Mysoline 50 mg Tablets are white uncoated tablets for oral use. One side of the tablet has a
single letter M, the other side of the tablet is plain.
Mysoline 250 mg Tablets are white uncoated tablets for oral use. One side of the tablet has
the letter M either side of a break-line. The other side of the tablet is plain.
Mysoline comes in containers of 100 tablets.
Marketing Authorisation Holder
40, avenue George V
75008 Paris
Recipharm Limited
Vale of Bardsley
Lancashire, OL7 9RR,
Allphamed PHARBIL Arzneimittel GmbH
Hildebrandstr. 10-12
37081 Göttingen
This leaflet was last approved on 01 August 2017
Is this leaflet hard to see and read? Phone 0800 198 5000 for help.
If you have any medical enquiry, please email

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.