Primidone Dosage

Medically reviewed by Drugs.com. Last updated on Sep 7, 2023.

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this regimen until a satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn.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this regimen until a satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn.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

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

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

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.

Precautions

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

Consult WARNINGS section for additional precautions.

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.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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