pharmacopeia
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/api/v1/drug/primidone

Mechanism of action

Sourced from openFDA

Mechanism-of-action class: Neurotransmitter Transporter Interactions.

Indications

Sourced from openFDA
  • Primidone, used alone or concomitantly with other anticonvulsants, is indicated in the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy.ICD-10: G40.909

Contraindications

Sourced from openFDA
  • Primidone is contraindicated in: 1) patients with porphyria and 2) patients who are hypersensitive to phenobarbital (see ACTIONS ).contraindicated

Dosage & administration

Sourced from openFDA

Usual Dosage 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 a day Days 7 to 9: 100 to 125 mg three times a day Day 10 to maintenance: 250 mg three times a day 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 t.i.d. or q.i.d.). If required, an increase to five or six 250 mg tablets daily may be made but daily doses should not exceed 500 mg q.i.d. Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations of primidone may be necessary for optimal dosage adjustment. The clinically effective serum level for primidone is between 5 to 12 µg/mL. INITIAL: ADULTS AND CHILDREN OVER 8 KEY: •=50 mg tablet; ●=250 mg tablet Day 1 2 3 4 5 6 AM •• •• •• NOON PM •• •• •• •• •• •• DAY 7 8 9 10 11 12 AM •• •• •• ● Adjust to Maintenance NOON •• •• •• ● PM •• •• •• ● 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. This regimen should be continued until satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn.

Warnings & precautions

Sourced from openFDA

The abrupt withdrawal of antiepileptic medication may precipitate status epilepticus. The therapeutic efficacy of a dosage regimen takes several weeks before it can be assessed. Suicidal Behavior and Ideation Antiepileptic drugs (AEDs), including primidone, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. Pooled analyses of 199 placebo-controlled clinical trials (mono- and adjunctive therapy) of 11 different AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted Relative Risk 1.8, 95% CI:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 AED-treated patients was 0.43%, compared to 0.24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide. The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed.

Adverse reactions

Sourced from openFDA

The most frequently occurring early side effects are ataxia and vertigo. These tend to disappear with continued therapy, or with reduction of initial dosage. Occasionally, the following have been reported: nausea, anorexia, vomiting, fatigue, hyperirritability, emotional disturbances, sexual impotency, diplopia, nystagmus, drowsiness and morbilliform skin eruptions. Granulocytopenia, agranulocytosis, and red-cell hypoplasia and aplasia, have been reported rarely. These and, occasionally, other persistent or severe side effects may necessitate withdrawal of the drug. Megaloblastic anemia may occur as a rare idiosyncrasy to primidone and to other anticonvulsants. The anemia responds to folic acid without necessity of discontinuing medication. To report SUSPECTED ADVERSE REACTIONS, contact Oxford Pharmaceuticals, LLC at 1-844-508-1455, 8:00 AM to 4.30 PM ET, Monday – Friday or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Approval history

Sourced from openFDA
  • Mar 8, 1954NDANDA009170Valeant
  • Dec 1, 1978ANDAANDA084903Lannett
  • Feb 7, 1979ANDAANDA083551Watson Labs
  • Feb 24, 2005ANDAANDA040586Oxford Pharms
  • Apr 23, 2008ANDAANDA040866Amneal Pharm
  • Oct 3, 2008ANDAANDA040862Chartwell Rx
  • Jun 28, 2022ANDAANDA214896Rubicon Research
  • Jan 23, 2024ANDAANDA218366Carnegie

FAERS reports

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Reference statistics only. FAERS reports are voluntarily submitted and are not incidence rates, safety signals, or causal evidence. Counts reflect reporting volume — how often a reaction was reported, not how often it occurs. For decision-grade use, consult openFDA and the FAERS Public Dashboard directly.
9,960 total reports matchedLatest report Share = reports listing the reaction ÷ total matched reports. Rows can sum to >100% because a single report often lists multiple reactions.
  1. 1Drug Ineffective8288.3%
  2. 2Fall6606.6%
  3. 3Fatigue6306.3%
  4. 4Tremor5755.8%
  5. 5Dizziness4914.9%
  6. 6Off Label Use4884.9%
  7. 7Diarrhoea4874.9%
  8. 8Nausea4624.6%
  9. 9Drug Interaction4034.0%
  10. 10Headache3933.9%
  11. 11Somnolence3833.8%
  12. 12Asthenia3573.6%
  13. 13Dyspnoea3543.6%
  14. 14Weight Decreased3313.3%
  15. 15Pain3233.2%

Literature

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Recent PubMed references pinned to Primidone as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

Clinical trials

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The 10 most recently updated of 11 ClinicalTrials.gov registrations naming Primidone as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

Frequently asked questions

How does Primidone work?
Mechanism-of-action class: Neurotransmitter Transporter Interactions.
What is Primidone used for?
According to FDA labeling, Primidone carries indications including: Primidone, used alone or concomitantly with other anticonvulsants, is indicated in the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.
What class of drug is Primidone?
Primidone is classified as Barbiturates and derivatives, Anti-epileptic Agent, Neurotransmitter Transporter Interactions, Decreased Central Nervous System Disorganized Electrical Activity, Neurotransmitter & Neuromuscular Transmitter Activity Alteration.
What are the brand names for Primidone?
Primidone is marketed under brand names including Mysoline.
What are the contraindications for Primidone?
Primidone labeling lists contraindications including: Primidone is contraindicated in: 1) patients with porphyria and 2) patients who are hypersensitive to phenobarbital (see ACTIONS ).. Always consult the full prescribing information and a clinician.
Note. Data for primidone is illustrative MVP content compiled from public sources. pharmacopeia is for educational and informational use only and is not a substitute for professional medical advice.

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