Mysoline: Effective Seizure Control with Established Efficacy
| Product dosage: 250 mg | |||
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| Package (num) | Per tab | Price | Buy |
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Synonyms | |||
Mysoline (primidone) is an established anticonvulsant medication indicated for the management of seizure disorders. As a barbiturate derivative, it exerts its therapeutic effect by reducing abnormal electrical activity in the brain, thereby stabilizing neuronal membranes and raising the seizure threshold. Its long-standing clinical history provides a well-understood profile for neurologists managing grand mal, psychomotor, and focal epileptic seizures. This product card provides a comprehensive overview for healthcare professionals to ensure informed prescribing and patient management.
Features
- Active Pharmaceutical Ingredient: Primidone
- Pharmacologic Class: Anticonvulsant, Barbiturate derivative
- Available Formulations: Scored, oral tablets (50 mg and 250 mg)
- Mechanism of Action: Raises the seizure threshold by decreasing neuron excitability and suppressing the spread of seizure activity from epileptogenic foci
- Metabolic Pathway: Hepatically metabolized to active metabolites, including phenobarbital and phenylethylmalonamide (PEMA)
Benefits
- Provides effective control and prophylaxis of tonic-clonic (grand mal) and complex partial (psychomotor) seizures.
- Offers a predictable pharmacokinetic profile with a long history of clinical use, supporting confident long-term therapeutic management.
- The dual active metabolites (primidone itself and phenobarbital) contribute to a multi-mechanistic approach to seizure suppression.
- Scored tablet formulation allows for dosage titration to achieve individualized therapeutic goals and optimize patient response.
Common use
Mysoline is primarily indicated for the control of grand mal, psychomotor, and focal epileptic seizures. It may be used as monotherapy or as an adjunctive treatment in patients whose seizures are not adequately controlled by other anticonvulsants. Its use is determined following a comprehensive neurological evaluation and diagnosis.
Dosage and direction
Dosage must be individualized for each patient based on clinical response and tolerability. Therapy should start at a low dose with gradual titration.
- Adults and children over 8 years: Initial dose is 100 to 125 mg at bedtime for the first 3 days. The dose may be gradually increased by 100 to 125 mg every 3 days to a usual maintenance dose of 250 mg three to four times daily. Doses up to 2 g daily may be required in some patients.
- Children under 8 years: Initial dose is 50 mg at bedtime for the first 3 days. The dose may be gradually increased by 50 mg every 3 days to a maintenance dose of 125 to 250 mg three times daily, or 10 to 25 mg/kg/day in divided doses.
- Administration: Tablets should be swallowed whole with a full glass of water. May be taken with or without food to minimize potential gastrointestinal upset. Consistent daily intake is crucial for maintaining stable serum levels.
Precautions
- Abrupt withdrawal may precipitate status epilepticus; dosage must be reduced gradually.
- Use with caution in patients with hepatic, renal, or pulmonary impairment, or those with a history of depression or suicidal ideation.
- May cause drowsiness, dizziness, or ataxia; patients should be cautioned about operating machinery or driving until their response to the drug is known.
- Periodic laboratory monitoring, including complete blood count and liver function tests, is recommended during prolonged therapy.
- Possesses a potential for psychological and physical dependence; use with caution in patients with a history of drug abuse.
Contraindications
Mysoline is contraindicated in patients with:
- Known hypersensitivity to primidone or any component of the formulation, or to barbiturates.
- Porphyria.
- Severe respiratory depression with airway obstruction.
- Severe hepatic dysfunction.
Possible side effect
Common adverse reactions are usually dose-related and may diminish with continued therapy or dosage adjustment.
- Very Common (>10%): Ataxia, vertigo, dizziness, nausea, anorexia, fatigue.
- Common (1-10%): Vomiting, diplopia (double vision), nystagmus, drowsiness, emotional disturbances, sexual impotence.
- Uncommon (<1%): Skin rashes, megaloblastic anemia, thrombocytopenia, agranulocytosis, peripheral neuropathy, osteomalacia (with long-term use).
- Patients should be monitored for the emergence or worsening of depression, suicidal thoughts, or unusual changes in behavior.
Drug interaction
Mysoline has a significant potential for pharmacokinetic and pharmacodynamic interactions.
- Enhanced CNS Depression: Concomitant use with alcohol, sedatives, hypnotics, anxiolytics, or other CNS depressants can result in additive effects.
- Enzyme Induction: As a potent inducer of hepatic cytochrome P450 enzymes (e.g., CYP3A4), primidone can accelerate the metabolism and reduce the efficacy of numerous drugs, including: oral anticoagulants (warfarin), corticosteroids, oral contraceptives, tricyclic antidepressants, certain antivirals, and other anticonvulsants (e.g., lamotrigine, valproate, carbamazepine).
- Other Anticonvulsants: Valproic acid may increase serum levels of primidone’s metabolite, phenobarbital. Isoniazid may inhibit the metabolism of primidone, increasing its serum concentration.
- A comprehensive review of a patient’s medication list is essential prior to initiation.
Missed dose
- If a dose is missed, it should be taken as soon as it is remembered.
- However, if it is almost time for the next scheduled dose, the missed dose should be skipped. The regular dosing schedule should be resumed.
- Do not double the dose to make up for the missed one, as this increases the risk of adverse effects.
Overdose
- Symptoms: Overdose is primarily characterized by profound CNS depression (coma, severe drowsiness, respiratory depression), hypotension, hypothermia, and pulmonary edema.
- Management: There is no specific antidote. Treatment is supportive and symptomatic, focusing on maintaining an adequate airway, ventilation, and hemodynamic stability. Gastric lavage may be considered if presentation is early. Hemodialysis may be useful due to the drug’s relatively low volume of distribution. Serum levels of primidone and phenobarbital should be monitored.
Storage
- Store at room temperature between 20°C to 25°C (68°F to 77°F).
- Protect from light and moisture.
- Keep in the original container, tightly closed.
- Keep out of reach of children and pets.
Disclaimer
This information is intended for educational purposes for healthcare professionals and is not a substitute for professional medical advice, diagnosis, or treatment. The prescribing physician is responsible for determining the appropriate dosage and monitoring therapy based on the individual patient’s condition. Always refer to the full official prescribing information before initiating treatment.
Reviews
“Mysoline remains a valuable tool in the epileptologist’s arsenal, particularly for certain hard-to-treat focal seizures. Its efficacy is well-documented, though the side effect profile necessitates careful patient selection and vigilant monitoring.” – Neurologist, 15 years of experience. “For a subset of my patients who have failed newer agents, primidone has provided remarkable seizure freedom. The key is a very slow titration to mitigate initial drowsiness and dizziness.” – Clinical Epileptologist. “The enzyme induction properties are a significant drawback in polypharmacy patients, often complicating the management of comorbidities. However, its low cost and proven track record ensure its continued place in therapy.” – Pharmacy Director.