primidone
Primidone, also known by its brand name Mysoline, is an antiseizure medication. It's used to treat different kinds of seizures in adults and children. This medication comes as a tablet that's taken by mouth usually a few times per day. People start at a low dose and then take gradually higher doses until they reach a maintenance dose. Side effects include sleepiness, problems with coordination, and feeling like the room is spinning (vertigo).
What is Primidone (Mysoline)?
What is Primidone (Mysoline) used for?
How Primidone (Mysoline) works
Primidone (Mysoline) is a type of anti-seizure medication. It's not exactly clear how it works. But it's thought to slow down brain activity to help control seizures.
Your body breaks primidone (Mysoline) down into other chemicals, one of which includes phenobarbital. Phenobarbital itself is a medication that helps calm the nerves in your brain to treat seizures.
Drug facts
Side effects of Primidone (Mysoline)
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
- Drowsiness
- Tiredness
- Dizziness
- Feeling like the room is spinning (vertigo)
- Problems with movement or coordination
Less Common Side Effects
- Nausea
- Vomiting
- Poor appetite
- Feeling irritable
- Feeling emotional or having mood swings
- Sexual dysfunction
- Double vision
- Eye twitching
- Rash
- Low blood cell counts
Primidone (Mysoline) serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Suicidal behavior or thoughts of self-harm
- Low blood cell counts: frequent fevers, chills, weakness, tiredness, trouble breathing, unusual or easy bruising or bleeding
The following Primidone (Mysoline) side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
Shakiness and unsteady walk
unsteadiness, trembling, or other problems with muscle control or coordination
Less common
Unusual excitement or restlessness (especially in children and in the elderly)
Rare
Chills
cough or hoarseness
fainting spells
fever and sore throat
fever with or without chills
general feeling of tiredness or weakness
irregular heartbeat
lower back or side pain
painful or difficult urination
pale skin
shortness of breath
skin rash
sores, ulcers, or white spots on the lips or in the mouth
unusual bleeding or bruising
unusual tiredness or weakness
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
Confusion
continuous, uncontrolled rolling eye movements
double vision
troubled breathing
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Clumsiness or unsteadiness
dizziness or lightheadedness
feeling of constant movement of self or surroundings
sensation of spinning
Less common
Decreased sexual ability
drowsiness
loss of appetite
mood or mental changes
nausea or vomiting
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
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Pros and cons of Primidone (Mysoline)
Pros
- Can take by itself or with other seizure medications
- Dose can be adjusted to find the best dose that controls your seizures
Cons
- Might take weeks to see the full effect of the medication on seizures
- Not usually a first-choice seizure medication
Pharmacist tips for Primidone (Mysoline)
- You can take primidone (Mysoline) with or without food.
- When you start primidone (Mysoline), your prescriber will give you a dosing schedule to follow. You'll begin at a low dose and slowly raise it until you get to your long-term (maintenance) dose.
- Your prescriber might adjust your primidone (Mysoline) dose by checking the medication levels in your blood. This helps them see if the amount of medication in your body is in the right range to work well for you. Make sure to get any blood tests done when your prescriber asks you to.
- Talk to your prescriber if you have trouble swallowing primidone (Mysoline) tablets. Only the 250 mg tablets can be safely cut in half with a pill splitter. Don't cut or crush any tablets unless your prescriber tells you it's okay.
- Primidone (Mysoline) can make you drowsy and dizzy. It can also make you have problems with movement or coordination and feel like the room is spinning. This often happens when you first start the medication or after you start a higher dose. These side effects usually go away as you get used to the medication. But let your prescriber know if they bother you too much or don't go away.
- Don't drive or do anything that needs your full attention until you know how primidone (Mysoline) affects you. This medication can cause side effects like drowsiness and dizziness. It can also slow your thinking and how well you move. This can make certain things like driving dangerous.
- Primidone (Mysoline) can raise the risk of suicidal thoughts and behavior. Tell your prescriber if you or your close ones notice any unusual changes in your mood or behavior. Call 911 right away if you have thoughts about hurting yourself.
- Don't change your dose or stop taking primidone (Mysoline) suddenly without talking to your prescriber first. Lowering the dose or stopping too fast can make your seizures come back and can be dangerous. If you want to stop, tell your prescriber. They'll help you slowly lower your dose safely before you can stop.
- Tell your prescriber right away if you are pregnant or planning to become pregnant while taking primidone (Mysoline). It's not clear if this medication is safe during pregnancy. Your prescriber can explain the risks and benefits. If you take the medication while pregnant, you're encouraged to join the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This helps researchers learn more about how safe anti-seizure medications are during pregnancy.
- If you're thinking of breastfeeding while taking primidone (Mysoline), talk to your prescriber. They can help you understand the risks and benefits. This medication can get into breast milk and might cause your baby to get very sleepy. If needed, your care team can discuss with you about safe feeding options.
Common questions about Primidone (Mysoline)
No, primidone (Mysoline) isn't a controlled substance. It isn't known to have a risk of being misused or addictive. The medication also isn't known to cause physical dependence.
Primidone (Mysoline) is sometimes called a first-generation barbiturate-type seizure medication. Your body breaks it down into a chemical called phenobarbital. Phenobarbital is a barbiturate and is available as a medication for seizures.
For the first couple days of starting primidone (Mysoline), it's usually best to take it at bedtime. This can help with side effects like sleepiness, dizziness, or trouble with coordination. Over the next days of treatment, your dosing schedule will change to twice a day, then 3 to 4 times a day long term. Try to space your doses out evenly during the day. If you're not sure when to take your doses, ask your prescriber or pharmacist for help.
Yes, primidone (Mysoline) is one of the recommended treatments for essential tremors. The American Academy of Neurology, lists it as a first-choice option because studies show it can help. Keep in mind that primidone (Mysoline) isn't FDA approved for essential tremors, so this is considered an off-label use. Talk to a neurologist to see if primidone (Mysoline) is a good option for you if you have essential tremors.
It takes about 2 to 3 days for most of primidone (Mysoline) to leave your body. This timing might be different for children and older adults. The time frame is estimated from the medication's half-life, which is how long it takes for half the dose to leave the body. Even though the medication can take a couple of days to clear after a single dose, it’s important to take it exactly as prescribed. This keeps the medication level stable in your body so it can work well to control your seizures. Ask your prescriber if you have questions about how long this medication stays in your system.
No. Primidone (Mysoline) generally isn't linked to weight gain, unlike some other seizure medications. Talk to your prescriber if you notice any weight gain that concerns you while taking primidone (Mysoline). They can help find out what's going on and give you tips on managing your weight.
There are many medications that can interact with primidone (Mysoline). Some examples are certain HIV medications. Others include a blood thinner called rivaroxaban (Xarelto) and the antifungal voriconazole. Tell your healthcare team about all the medications you take or plan to take. They can check your list of medications to make sure everything is safe together. Your prescriber might need to adjust your medications to keep you safe.
It's best to avoid drinking alcohol while taking primidone (Mysoline). Alcohol can make side effects like feeling sleepy and dizzy worse. Drinking a lot of alcohol can also raise your risk of having a seizure. Talk to your care team about your drinking habits to make sure you stay safe while taking primidone (Mysoline).
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Risks and warnings for Primidone (Mysoline)
Primidone (Mysoline) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk of suicidal thoughts and behavior
- Risk factors: History of depression | Taking other anti-seizure medications
Primidone (Mysoline) can raise your risk of having suicidal thoughts or behavior. The risk can appear as early as 1 week after you start taking this medication.
Tell your friends and family to watch for any signs of depression or unusual changes in mood or behavior. If this happens, let your prescriber know. If you start thinking about hurting yourself, call 911 right away.
Problems with concentration and movement
- Risk factors: Drinking alcohol | Taking other medications that can cause drowsiness or dizziness
Some people taking primidone (Mysoline) have trouble concentrating or coordinating their movements. The medication can also make you feel very dizzy or drowsy. This can make it harder to think clearly, react quickly, or stay focused.
Your risk is higher if you take other medications that cause drowsiness. Some can include benzodiazepines, muscle relaxants, and sleep medications. Drinking alcohol with primidone (Mysoline) can also make these side effects worse.
Make sure you know how primidone (Mysoline) affects you before you drive or do anything that needs your full attention. Talk to your healthcare team if the medication makes you too sleepy or if side effects make it hard to do your daily activities.
Withdrawal seizures
Don't suddenly stop taking primidone (Mysoline) without talking to your prescriber first. Stopping too fast can raise the risk of seizures. Sometimes, these withdrawal seizures can be serious and dangerous.
If you need to stop primidone (Mysoline), talk to your prescriber. They'll help lower your dose slowly until you can stop it completely. This can help lower your risk of withdrawal seizures.
Primidone (Mysoline) dosage
Tablet| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 50mg | 90 tablets | $17.88 | $0.20 |
| 250mg | 90 tablets | $13.93 | $0.15 |
| 125mg | 90 tablets | $48.52 | $0.54 |
Typical dosage for Primidone (Mysoline)
-
Adults and children ages 8 years and older
- Days 1 to 3: The typical dose is 100 mg to 125 mg by mouth at bedtime.
- Days 4 to 6: The typical dose is 100 mg to 125 mg by mouth twice a day.
- Days 7 to 9: The typical dose is 100 mg to 125 mg by mouth three times a day.
- Day 10 and thereafter: The typical dose is 250 mg by mouth three or four times a day. Some people might need a higher dose, but the maximum dose is 500 mg taken four times a day.
-
Children under 8 years old
- Days 1 to 3: The typical dose is 50 mg by mouth at bedtime.
- Days 4 to 6: The typical dose is 50 mg by mouth twice a day.
- Days 7 to 9: The typical dose is 100 mg by mouth twice a day.
- Day 10 and thereafter: The typical maintenance dose is 125 mg to 250 mg by mouth three times a day. Another option is based on weight: 10 mg/kg to 25 mg/kg per day, split into multiple doses during the day.
Interactions between Primidone (Mysoline) and other drugs
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
- Artemether
- Atazanavir
- Boceprevir
- Cobicistat
- Delamanid
- Delavirdine
- Elvitegravir
- Lopinavir
- Lumefantrine
- Lurasidone
- Maraviroc
- Nisoldipine
- Rilpivirine
- Ritonavir
- Telaprevir
- Tenofovir Alafenamide
- Tipranavir
- Voriconazole
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Alfentanil
- Alprazolam
- Amiodarone
- Amobarbital
- Anisindione
- Apixaban
- Apremilast
- Aprobarbital
- Avapritinib
- Axitinib
- Bedaquiline
- Benzhydrocodone
- Brigatinib
- Bromazepam
- Buprenorphine
- Butabarbital
- Butalbital
- Butorphanol
- Calcifediol
- Calcium Oxybate
- Cannabidiol
- Capmatinib
- Carisoprodol
- Ceritinib
- Cetirizine
- Chloral Hydrate
- Chlordiazepoxide
- Chlorzoxazone
- Clobazam
- Clonazepam
- Clorazepate
- Cobimetinib
- Codeine
- Dabigatran Etexilate
- Daclatasvir
- Dantrolene
- Darunavir
- Deflazacort
- Desogestrel
- Diazepam
- Dicumarol
- Dienogest
- Dihydrocodeine
- Dolutegravir
- Doxylamine
- Dronedarone
- Drospirenone
- Elbasvir
- Encorafenib
- Entrectinib
- Erdafitinib
- Esketamine
- Eslicarbazepine Acetate
- Estazolam
- Estradiol
- Ethchlorvynol
- Ethinyl Estradiol
- Ethynodiol
- Etonogestrel
- Exemestane
- Fedratinib
- Fentanyl
- Flibanserin
- Flunitrazepam
- Flurazepam
- Gabapentin
- Gabapentin Enacarbil
- Gestodene
- Glasdegib
- Grazoprevir
- Halazepam
- Hemin
- Hydrocodone
- Hydromorphone
- Ketamine
- Ketazolam
- Lamotrigine
- Lefamulin
- Lemborexant
- Levocetirizine
- Levoleucovorin
- Levonorgestrel
- Levorphanol
- Linagliptin
- Lofexidine
- Lorazepam
- Lorlatinib
- Lormetazepam
- Loxapine
- Lumateperone
- Lurbinectedin
- Magnesium Oxybate
- Medazepam
- Medroxyprogesterone
- Meperidine
- Mephenesin
- Mephobarbital
- Meprobamate
- Mestranol
- Metaxalone
- Methadone
- Methocarbamol
- Methohexital
- Metoclopramide
- Midazolam
- Morphine
- Morphine Sulfate Liposome
- Nalbuphine
- Naloxegol
- Neratinib
- Nifedipine
- Nilotinib
- Nintedanib
- Nitrazepam
- Nomegestrol
- Norelgestromin
- Norethindrone
- Norgestimate
- Norgestrel
- Olaparib
- Orlistat
- Oxazepam
- Oxycodone
- Oxymorphone
- Panobinostat
- Pemigatinib
- Pentazocine
- Pentobarbital
- Perampanel
- Periciazine
- Phenindione
- Phenobarbital
- Phenprocoumon
- Piperaquine
- Potassium Oxybate
- Prazepam
- Pregabalin
- Pretomanid
- Quazepam
- Remifentanil
- Remimazolam
- Rimegepant
- Rivaroxaban
- Saquinavir
- Scopolamine
- Secobarbital
- Segesterone
- Selpercatinib
- Selumetinib
- Simeprevir
- Sodium Oxybate
- Sufentanil
- Tacrolimus
- Tapentadol
- Tazemetostat
- Temazepam
- Thiopental
- Tramadol
- Triazolam
- Ubrogepant
- Ulipristal
- Valproic Acid
- Vandetanib
- Velpatasvir
- Venetoclax
- Vilazodone
- Voclosporin
- Vortioxetine
- Voxelotor
- Voxilaprevir
- Zanubrutinib
- Zolpidem
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Betamethasone
- Cannabis
- Carbamazepine
- Cortisone
- Ginkgo
- Hydrocortisone
- Leucovorin
- Methylprednisolone
- Ospemifene
- Prednisolone
- Prednisone
- Rufinamide
- Tiagabine
- Triamcinolone
- Warfarin
How much does Primidone (Mysoline) cost?
Primidone (Mysoline) contraindications
Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Primidone (Mysoline) will not be safe for you to take.
- Porphyria (a rare genetic condition)
- Allergy to phenobarbital
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