Primidone (patient information)

Why is this medication prescribed

Primidone is used to control seizures.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

How should this medicine be used

Primidone comes as a tablet and suspension (liquid) to take by mouth. It usually is taken once a day at bedtime when you first use it, and then the dosage is gradually increased to three or four times a day. It may be taken with food. Shake the suspension well before each use. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take primidone exactly as directed. Do not take more or less of it or take it more often than your doctor tells you to.

This medication must be taken regularly to be effective. Do not skip doses even if you feel that you do not need them. Do not stop taking this drug until your doctor specifically tells you to do so. Stopping the drug abruptly can cause seizures. Your doctor probably will decrease your dose gradually.

Other uses for this medicine

Primidone is also used to treat tremors. Talk to your doctor about the possible risks of using this drug for your condition.

What special precautions should I follow

Before taking primidone

tell your doctor and pharmacist if you are allergic to primidone or any other drugs. Also, tell your doctor if you ever had a bad reaction to amobarbital (Amytal), butabarbital (Butisol), pentobarbital (Nembutal), phenobarbital, or secobarbital (Seconal).
tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially acetazolamide (Diamox); anticoagulants ('blood thinners') such as warfarin (Coumadin); antihistamines; carbamazepine (Tegretol); disulfiram (Antabuse); doxycycline (Vibramycin); griseofulvin (Fulvicin); isoniazid (INH, Laniazid, Nydrazid); MAO inhibitors [phenelzine (Nardil) or tranylcypromine (Parnate)]; medications for depression, seizures, pain, asthma, colds, or allergies; muscle relaxants; nicotinamide; oral contraceptives; phenytoin (Dilantin); sedatives; sleeping pills; steroids; tranquilizers; valproic acid (Depakene); and vitamins.
tell your doctor if you have or have ever had anemia or lung, kidney, or liver disease.
use a method of birth control other than oral contraceptives while taking this medication. Primidone can decrease the effectiveness of oral contraceptives.
tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking primidone, call your doctor immediately.
if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking primidone.
you should know that this drug may make you drowsy. Do not drive a car or operate machinery until you know how this drug affects you.
remember that alcohol can add to the drowsiness caused by this drug.

What should I do if I forget a dose

Take the missed dose as soon as you remember it and take any remaining doses for that day at evenly spaced intervals. However, if you remember a missed dose at the time you are scheduled to take the next one, skip the missed dose completely. Do not take a double dose to make up for the missed one.

Side effects

Mild side effects

Side effects from primidone may occur and include:

drowsiness
incoordination
irritability
excitement (in children)
upset stomach
tiredness
headache
changes in appetite

Tell your doctor if any of these symptoms are severe or do not go away:

restlessness or excitement
hair loss
swollen eyelids or legs
double vision
blurred vision
changes in sex drive or ability

Severe side effects

If you experience any of the following symptoms, call your doctor immediately:

seizures
sore throat
fever
severe skin rash
yellowing of the skin or eyes
dark urine
bloody nose
unusual bleeding
tiny purple skin spots
easy bruising

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/MedWatch/report.htm] or by phone [1-800-332-1088].

What storage conditions are needed for this medicine

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Do not freeze the suspension. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

What other information should I know

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to primidone. Your dose may need to be adjusted frequently, especially when you first take primidone.

Differences in effectiveness may be seen with different brands of this medication. Switching brands is not recommended without the advice of your pharmacist. Call your doctor if you continue to have seizures. Carry identification (Medic Alert) stating that you have epilepsy and that you are taking primidone.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Brand names

Mysoline®