Primidone

Primidone is a prescription medication used to treat seizures in adults and children. Primidone belongs to a group of drugs called anticonvulsants, which work by decreasing abnormal electrical activity in the brain.

This medication comes in tablet form and is taken one to three times a day, with or without food.

Common side effects of primidone include drowsiness, problems with walking or moving, and dizziness. Do not drive or operate machinery until you know how primidone will affect you.

Primidone is a prescription medication used alone or with other medicines to treat people with:

• generalized tonic-clonic (grand mal) seizures
• complex partial (psychomotor) seizures
• partial (focal) epileptic seizures

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Primidone may be found in some form under the following brand names:

• Mysoline

See "Drug Precautions" section.

Primidone may cause other serious side effects including:

• Sleepiness that can be severe, especially when you first start taking primidone.
• Primidone may rarely cause blood problems. Symptoms may include:
  • fever, swollen glands, or sore throat that come and go or do not go away
  • Frequent infections or an infection that does not go away
  • tiredness
  • shortness of breath
• Primidone may rarely cause allergic reactions. Symptoms may include:
  • skin rash
  • hives
  • sores in your mouth
  • blistering or peeling skin

The most common side effects of primidone include:

• problems with walking and moving
• feelings of dizziness, spinning, or swaying (vertigo)

These are not all the possible side effects of primidone. For more information, ask your healthcare provider or pharmacist.

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your healthcare provider about all of the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• anticoagulants ('blood thinners') such as warfarin (Coumadin, Jantoven)
• antidepressants
• disulfiram (Antabuse)
• doxycycline (Vibramycin)
• griseofulvin (Grifulvin)
• medications for anxiety, mental illness, and pain
• other medications for seizures such as oxcarbazepine (Trileptal), phenobarbital, phenytoin (Dilantin), and valproic acid (Depakene, Depakote)
• oral contraceptives (birth control pills)
• oral steroids such as dexamethasone (Decadron, Dexone) and prednisone (Deltasone)
• sedatives
• sleeping pills
• tranquilizers

This is not a complete list of primidone drug interactions. Ask your healthcare provider or pharmacist for more information.

Do not stop taking primidone without first talking to your healthcare provider.

Stopping primidone suddenly can cause serious problems.

Primidone can cause serious side effects, including:

Like other antiepileptic drugs, primidone may cause suicidal thoughts or actions in a very small number of people, about 1 in 500.

Call a healthcare provider right away if you have any of these symptoms, especially if they are new, worse, or worry you:

• thoughts about suicide or dying
• attempts to commit suicide
• new or worse depression
• new or worse anxiety
• feeling agitated or restless
• panic attacks
• trouble sleeping (insomnia)
• new or worse irritability
• acting aggressive, being angry, or violent
• acting on dangerous impulses
• an extreme increase in activity and talking (mania)
• other unusual changes in behavior or mood

Watch for early symptoms of suicidal thoughts and actions:

• Pay attention to any changes, especially sudden changes, in mood, behaviors, thoughts, or feelings.
• Keep all follow-up visits with your healthcare provider as scheduled.

Call your healthcare provider between visits as needed, especially if you are worried about symptoms.

Do not stop primidone without first talking to a healthcare provider.

• Stopping primidone suddenly can cause serious problems. Stopping a seizure medicine suddenly in a patient who has epilepsy can cause seizures that will not stop (status epilepticus).

Suicidal thoughts or actions can be caused by things other than medicines. If you have suicidal thoughts or actions, your healthcare provider may check for other causes.

Do not take primidone if you:

• have a genetic disorder called porphyria
• are allergic to phenobarbital

Warning:

• Primidone can make you sleepy or dizzy. Do not drink alcohol or take other drugs that make you sleepy or dizzy while taking  primidone without first discussing this with your healthcare provider. Taking primidone with alcohol or drugs that cause sleepiness or dizziness may make your sleepiness or dizziness worse.
• Do not drive, operate heavy machinery, or do other dangerous activities until you know how primidone affects you. Primidone can slow your thinking and motor skills.

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of primidone there are no specific foods that you must exclude from your diet when receiving primidone.

Before you take primidone, tell your healthcare provider if you:

• have or have had depression, mood problems or suicidal thoughts or behavior
• have any other medical conditions
• are pregnant or planning to become pregnant. See "Pregnant" section.
• are breastfeeding or plan to breastfeed. See "Lactation" section.

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Taking primidone with certain other medicines can cause side effects or affect how well they work. Do not start or stop other medicines without talking to your healthcare provider.

Know the medicines you take. Keep a list of them and show it to your healthcare provider and pharmacist each time you get a new medicine.

Tell your healthcare provider if you are pregnant or planning to become pregnant. Primidone may harm your unborn baby. Tell your healthcare provider right away if you become pregnant while taking primidone. You and your healthcare provider will decide if you should take primidone while you are pregnant.

• If you become pregnant while taking primidone, talk to your healthcare provider about registering with the North American Antiepileptic Drug (NAAED) Pregnancy Registry. You can enroll in this registry by calling 1-888-233-2334. The purpose of this registry is to collect information about the safety of antiepileptic drugs during pregnancy.

Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Primidone can pass into breast milk. Talk to your healthcare provider about the best way to feed your baby if you take primidone.

Take primidone exactly as prescribed. Your healthcare provider will tell you how much primidone to take and when to take it.

• Primidone comes as a tablet to be taken one to three times daily, with or without food.
• Take primidone at the same time(s) each day.
• Your healthcare provider may change your dose. Do not change your dose without talking to your healthcare provider.
• Do not stop taking primidone without first talking to your healthcare provider. Stopping primidone suddenly can cause serious problems.
• If you take too much primidone, call your healthcare provider or local Poison Control Center right away.

What to avoid while taking primidone:

• Primidone can make you sleepy or dizzy. Do not drink alcohol or take other drugs that make you sleepy or dizzy while taking primidone without first discussing this with your healthcare provider. Taking primidone with alcohol or drugs that cause sleepiness or dizziness may make your sleepiness or dizziness worse.
• Do not drive, operate heavy machinery, or do other dangerous activities until you know how primidone affects you. Primidone can slow your thinking and motor skills.

Take primidone exactly as prescribed by your doctor. Follow the directions on your prescription label carefully. Your doctor will determine the best dose for you.

Patients 8 years of age and older who have received no previous treatment may be started on primidone according to the following regimen using either 50 mg or scored 250 mg primidone tablets:

Days 1 to 3: 100 to 125 mg at bedtime.
Days 4 to 6: 100 to 125 mg twice daily.
Days 7 to 9: 100 to 125 mg three times daily.
Day 10 to maintenance: 250 mg three times daily.

For most adults and children 8 years of age and over, the usual maintenance dosage is three to four 250 mg primidone tablets in divided doses (250 mg three or four times daily). If required, an increase to five or six 250 mg tablets daily may be made but daily doses should not exceed 500 mg four times daily.

In patients already receiving other anticonvulsants, primidone should be started at 100 to 125 mg at bedtime and gradually increased to maintenance level as the other drug is gradually decreased.

For children under 8 years of age, the following regimen may be used:

Days 1 to 3: 50 mg at bedtime.
Days 4 to 6: 50 mg twice daily.
Days 7 to 9: 100 mg twice daily.
Day 10 to maintenance: 125 mg three times daily to 250 mg three times daily.

For children under 8 years of age, the usual maintenance dosage is 125 to 250 mg three times daily or, 10 to 25 mg/kg/day in divided doses.

If you take too much primidone, call your healthcare provider or local Poison Control Center right away.

Store primidone at room temperature between 68°F to 77°F (20°C to 25°C) in a tight, light-resistant container.

Keep primidone and all medicines out of the reach of children.