Primidone

By Medically reviewed by hellodoktor

Generic Name: Primidone Brand Name(s): Generics only. No brands available.

Uses

What is Primidone used for?

Primidone is used alone or with other medications to control seizures. Controlling and reducing seizures lets you do more of your normal daily activities, reduces your risk of harm when you lose consciousness, and lessens your risk for a possibly life-threatening condition of frequent, repeated seizures. Primidone belongs to a class of drugs known as barbiturate anticonvulsants. It works by controlling the abnormal electrical activity in the brain that occurs during a seizure.

How should I take Primidone?

Take this medication by mouth with or without food, usually 3-4 times daily or as directed by your doctor. Take with food or milk if stomach upset occurs. Your doctor may direct you to start this medication at a low dose at bedtime and gradually increase your dose to prevent side effects such as drowsiness and dizziness. If you are changing from a different anticonvulsant to primidone, your doctor may direct you to continue your old medication and slowly lower the dose as you begin taking primidone. Follow your doctor’s instructions carefully.

Dosage is based on your medical condition, blood levels of primidone, use of other medications to treat seizures, and response to treatment. It may take several weeks to reach the best dose for you.

This medication works best when the amount of drug in your body is kept at a constant level. Therefore, take this drug at evenly spaced intervals. To help you remember, take it at the same times each day.

Do not stop taking this medication (and other anticonvulsant medications) without consulting your doctor. Your seizures may worsen or cause a very severe seizure that is difficult to treat (status epilepticus) when this drug is suddenly stopped.

This medication may cause withdrawal reactions, especially if it has been used regularly for a long time or in high doses. In such cases, withdrawal symptoms (such as anxiety, hallucinations, twitching, trouble sleeping) may occur if you suddenly stop using this medication. Withdrawal from primidone can be severe and include seizures and (rarely) death. To prevent withdrawal reactions, your doctor may reduce your dose gradually. Consult your doctor or pharmacist for more details, and report any withdrawal reactions right away.

Though it helps many people, this medication may sometimes cause addiction. This risk may be higher if you have a substance use disorder (such as overuse of or addiction to drugs/alcohol). Take this medication exactly as prescribed to lower the risk of addiction. Ask your doctor or pharmacist for more details.

Tell your doctor if your seizure control worsens (such as the number of seizures increases).

How do I store Primidone?

Primidone is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Primidone in the bathroom or the freezer. There may be different brands of Primidone that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Primidone down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Primidone?

Before taking primidone, tell your doctor or pharmacist if you are allergic to it; or to other barbiturates (such as phenobarbital); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: certain hormone problems (adrenal disease such as Addison’s disease), kidney problems, liver problems, lung disease (such as sleep apnea, chronic obstructive pulmonary disease-COPD), mental/mood disorders (such as depression, thoughts of suicide), personal or family history of a substance use disorder (such as overuse of or addiction to drugs/alcohol), personal/family history of a certain blood disorder (porphyria), certain vitamin deficiencies (folic acid, vitamin K).

This drug may make you dizzy or drowsy. Alcohol or marijuana can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Older adults may be more sensitive to the effects of this drug, especially drowsiness and dizziness. However, this drug can often cause excitement or confusion instead of drowsiness in older adults.

Children may be more sensitive to the side effects of the drug. This drug can often cause excitement instead of drowsiness in young children.

This medication is not recommended for use during pregnancy. It may harm an unborn baby. However, since untreated seizures are a serious condition that can harm both a pregnant woman and her unborn baby, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately talk to your doctor about the benefits and risks of using this medication during pregnancy. Since birth control pills, patches, implants, and injections may not work if taken with this medication, discuss reliable forms of birth control with your doctor.

This medication may lower your folic acid and vitamin K levels, increasing the risk of spinal cord defects. Therefore, check with your doctor to make sure you are taking enough folic acid and vitamin K. Infants born to mothers who have been using this medication during pregnancy may also have symptoms such as fussiness, shaking, or bleeding. Tell the doctor right away if you notice any of these symptoms in your newborn.

This medication passes into breast milk and may cause excessive sleepiness or feeding problems in the nursing infant. Consult your doctor before breast-feeding.

Is it safe during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this Primidone during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Primidone. Primidone is pregnancy risk category N according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown

Side effects

What side effects can occur from Primidone?

Dizziness, drowsiness, excitation, tiredness, headache, loss of appetite, nausea, or vomiting may occur as your body adjusts to the medication. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if any of these unlikely but serious side effects occur: staggering walk/clumsiness, decreased sexual ability/interest, double vision.

A small number of people who take anticonvulsants for any condition (such as seizure, bipolar disorder, pain) may experience depression, suicidal thoughts/attempts, or other mental/mood problems. Tell your doctor right away if you or your family/caregiver notice any unusual/sudden changes in your mood, thoughts, or behavior including signs of depression, suicidal thoughts/attempts, thoughts about harming yourself.

Tell your doctor right away if any of these rare but very serious side effects occur: easy bruising/bleeding, fainting, slow heartbeat, severe tiredness/weakness, pale skin, fast/slow/shallow breathing.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any of the following symptoms of a serious allergic reaction: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with Primidone?

Some products that may interact with this drug include: darunavir, etravirine, orlistat, rilpivirine.

Other medications can affect the removal of primidone from your body, which may affect how primidone works. Examples include St. John’s wort, among others.

This medication can speed up the removal of other medications from your body, which may affect how they work. Examples of affected drugs include artemether/lumefantrine, asunaprevir, atazanavir, boceprevir, cobicistat, lurasidone, ranolazine, sofosbuvir, sorafenib, voriconazole, certain calcium channel blockers such as felodipine/nimodipine, among others.

This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use reliable backup birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.

The risk of serious side effects (such as slow/shallow breathing, severe drowsiness/dizziness) may be increased if this medication is taken with other products that may also cause drowsiness or breathing problems. Tell your doctor or pharmacist if you are taking other products such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana, other drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

Primidone is very similar to phenobarbital. Do not use medications containing phenobarbital while using primidone.

Primidone may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Primidone?

Primidone may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Primidone?

Primidone may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this Primidone.

What is the dose of Primidone for an adult?

Usual Adult Dose for Epilepsy

For Patients Who Have Not Received Any Previous Treatment:

-Days 1 to 3: 100 to 125 mg orally at bedtime

-Days 4 to 6: 100 to 125 mg orally 2 times a day

-Days 7 to 9: 100 to 125 mg orally 3 times a day

-Day 10 onward: 250 mg orally 3 to 4 times a day, increasing up to 5 or 6 times a day if necessary

-Maximum dose: 500 mg orally 4 times a day (2 g daily)

For Patients Already Receiving Other Anticonvulsants:

100 to 125 mg orally at bedtime and gradually increase to maintenance level as the other drug is gradually decreased. Continue this regimen until a satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn. When therapy with this drug alone is the objective, the transition from concomitant therapy should not be completed in less than 2 weeks.

Comments:

-Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations may be necessary for optimal dosage adjustment. The clinically effective serum level for this drug is between 5 to 12 mcg/mL.

-This drug may be taken with or without food.

Use: For the control of grand mal, psychomotor, focal, and sometimes grand mal seizures refractory to other anticonvulsant therapy, given alone or concomitantly with other anticonvulsants

Usual Adult Dose for Seizures

For Patients Who Have Not Received Any Previous Treatment:

-Days 1 to 3: 100 to 125 mg orally at bedtime

-Days 4 to 6: 100 to 125 mg orally 2 times a day

-Days 7 to 9: 100 to 125 mg orally 3 times a day

-Day 10 onward: 250 mg orally 3 to 4 times a day, increasing up to 5 or 6 times a day if necessary

-Maximum dose: 500 mg orally 4 times a day (2 g daily)

For Patients Already Receiving Other Anticonvulsants:

100 to 125 mg orally at bedtime and gradually increase to maintenance level as the other drug is gradually decreased. Continue this regimen until a satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn. When therapy with this drug alone is the objective, the transition from concomitant therapy should not be completed in less than 2 weeks.

Comments:

-Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations may be necessary for optimal dosage adjustment. The clinically effective serum level for this drug is between 5 to 12 mcg/mL.

-This drug may be taken with or without food.

Use: For the control of grand mal, psychomotor, focal, and sometimes grand mal seizures refractory to other anticonvulsant therapy, given alone or concomitantly with other anticonvulsants

Dose Adjustments

The total daily dose is usually best divided and given in 2 equal amounts, one in the morning and the other in the evening. In certain patients, it may be preferable to give a larger dose when the seizures are more frequent; for instance: 1) if the attacks are nocturnal then all or most of the day’s dose may be given in the evening; 2) if the attacks are associated with some event such as menstruation, a slight increase in the dose may be appropriate.

Dialysis

This drug is removed by hemodialysis.

Other Comments

Administration advice:

-This drug may be taken with or without food.

General:

-It may take several weeks before the therapeutic efficacy of a dosage regimen can be assessed.

Monitoring:

-The manufacturer recommends a complete blood count (CBC) and sequential multiple analysis 12 (SMA-12) every 6 months that a patient is taking this drug.

Patient advice:

-Patients and families should be counseled that AEDs can increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to healthcare providers.

What is the dose of Primidone for a child?

Usual Pediatric Dose for Epilepsy

8 years of age and older:

-For Patients Who Have Not Received Any Previous Treatment:

Days 1 to 3: 100 to 125 mg orally at bedtime

Days 4 to 6: 100 to 125 mg orally 2 times a day

Days 7 to 9: 100 to 125 mg orally 3 times a day

Day 10 onward: 250 mg orally 3 to 4 times a day, increasing up to 5 or 6 times a day if necessary

Maximum dose: 500 mg orally 4 times a day (2 g daily)

-For Patients Already Receiving Other Anticonvulsants:

100 to 125 mg orally at bedtime and gradually increase to maintenance level as the other drug is gradually decreased. Continue this regimen until a satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn. When therapy with this drug alone is the objective, the transition from concomitant therapy should not be completed in less than 2 weeks.

Less than 8 years:

-Days 1 to 3: 50 mg orally daily at bedtime

-Days 4 to 6: 50 mg orally 2 times a day

-Days 7 to 9: 100 mg orally 2 times a day

-Day 10 to maintenance: 125 mg orally 3 times a day to 250 mg 3 times a day

-Usual maintenance dose: 125 to 250 mg orally 3 times daily OR 10 to 25 mg/kg/day orally in divided doses

Comments:

-Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations may be necessary for optimal dosage adjustment. The clinically effective serum level for this drug is between 5 to 12 mcg/mL.

-This drug may be taken with or without food.

Use: For the control of grand mal, psychomotor, focal, and sometimes grand mal seizures refractory to other anticonvulsant therapy, given alone or concomitantly with other anticonvulsants

Usual Pediatric Dose for Seizures

8 years of age and older:

-For Patients Who Have Not Received Any Previous Treatment:

Days 1 to 3: 100 to 125 mg orally at bedtime

Days 4 to 6: 100 to 125 mg orally 2 times a day

Days 7 to 9: 100 to 125 mg orally 3 times a day

Day 10 onward: 250 mg orally 3 to 4 times a day, increasing up to 5 or 6 times a day if necessary

Maximum dose: 500 mg orally 4 times a day (2 g daily)

-For Patients Already Receiving Other Anticonvulsants:

100 to 125 mg orally at bedtime and gradually increase to maintenance level as the other drug is gradually decreased. Continue this regimen until a satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn. When therapy with this drug alone is the objective, the transition from concomitant therapy should not be completed in less than 2 weeks.

Less than 8 years:

-Days 1 to 3: 50 mg orally daily at bedtime

-Days 4 to 6: 50 mg orally 2 times a day

-Days 7 to 9: 100 mg orally 2 times a day

-Day 10 to maintenance: 125 mg orally 3 times a day to 250 mg 3 times a day

-Usual maintenance dose: 125 to 250 mg orally 3 times daily OR 10 to 25 mg/kg/day orally in divided doses

Comments:

-Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations may be necessary for optimal dosage adjustment. The clinically effective serum level for this drug is between 5 to 12 mcg/mL.

-This drug may be taken with or without food.

Use: For the control of grand mal, psychomotor, focal, and sometimes grand mal seizures refractory to other anticonvulsant therapy, given alone or concomitantly with other anticonvulsants

Precautions

Safety and efficacy have not been established in patients younger than 1 year.

How is Primidone available?

Primidone is available in the following dosage forms and strengths:

  • Oral tablet,
  • Oral suspension.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Primidone, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: April 21, 2018 | Last Modified: September 12, 2019

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