Vigabatrin Dosage

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Seizure Prophylaxis

Initial dose: 1 g orally daily (administered as one 500 mg orally 2 times daily) with or without food

The total daily dose may be increased in 500 mg increments at weekly intervals depending on response.

Recommended dose: 3 g orally daily (1.5 g orally 2 times daily)

A 6 g daily dose has not been shown to confer additional benefit compared to the 3 g daily dose and is associated with an increased incidence of adverse events.

Approved indication: For adults and children 10 years of age and older as adjunctive therapy for refractory complex partial seizures (CPS) who have inadequately responded to several alternative treatments and for whom the potential benefits outweigh the risk of vision loss. Vigabatrin is not indicated as a first line agent for complex partial seizures.

Usual Pediatric Dose for Epilepsy

Infantile Spasms:
1 month to 2 years of age:
Initial dose: 50 mg/kg/day of vigabatrin oral solution given in two divided doses with or without food. The dose may be titrated by 25 to 50 mg/kg/day increments every 3 days up to a maximum of 150 mg/kg/day.

The entire contents of the appropriate number of packets (500 mg/packet) of powder should be emptied into an empty cup, and should be dissolved in 10 mL of cold or room temperature water per packet using the 10 mL oral syringe supplied with the medication. The concentration of the final solution is 50 mg/mL.

Each individual dose should be prepared immediately before use and administered cold or at room temperature.

Approved indication: As monotherapy for pediatric patients who are 1 month to 2 years of age with infantile spasms (IS) and for whom the potential benefits outweigh the potential risk of vision loss.

Usual Pediatric Dose for Seizure Prophylaxis

10 to 16 years of age and 25 to 60 kg:
-Initial dose: 500 mg orally daily (administered as one 250 mg orally 2 times daily) with or without food
-Maintenance dose: Total daily dose may be increased at weekly intervals to 2 gm orally daily (1 g orally 2 times daily).
-Patients weighing more than 60 kg should be dosed according to adult guidelines.

Approved indication: For children 10 to 16 years of age as adjunctive therapy for refractory complex partial seizures (CPS) who have inadequately responded to several alternative treatments and for whom the potential benefits outweigh the risk of vision loss. Vigabatrin is not indicated as a first line agent for complex partial seizures.

Renal Dose Adjustments

Infants with renal impairment: Data not available

Patients 10 years of age and older and adults:
-Mild renal impairment (CrCl 51 to 80 mL/min): Decrease dose by 25%
-Moderate renal impairment (CrCl 31 to 50 mL/min): Decrease dose by 50%
-Severe renal impairment (CrCl 11 to 30 mL/min): Decrease dose by 75%

Liver Dose Adjustments

Data not available

Dose Adjustments

Vigabatrin dose tapering:
-Adults and children 16 years of age and older: Decrease the daily dose 1 g orally daily each week until discontinued.
-Children 10 to 16 years of age and 25 to 60 kg: Decrease the daily dose by one-third each week for 3 weeks.
-Children 1 month to 2 years of age: Decrease the daily dose by 25 to 50 mg/kg every 3 to 4 days.

Oral administration of a single dose of 1.5 g of vigabatrin to elderly patients (over 65 years of age) with reduced creatinine clearance (less than 50 mL/min) has been associated with moderate to severe sedation and confusion in 4 of 5 patients, lasting for up to 5 days. The renal clearance of vigabatrin was 36% lower in healthy elderly subjects (over 65 years of age) than in young healthy males. Adjustment of dose or frequency of administration should be considered. Such patients may respond to a lower maintenance dose. Other reported clinical experience has not identified differences in responses between the elderly and younger patients.

Precautions

Consult WARNINGS section for dosing related precautions.

Dialysis

The effect of dialysis on vigabatrin clearance has not been adequately studied. In isolated case reports in renal failure patients receiving therapeutic doses of vigabatrin, hemodialysis reduced vigabatrin plasma concentrations by 40 to 60%.

Other Comments

The lowest dose and shortest exposure to vigabatrin should be used that is consistent with clinical objectives. Because of the risk of permanent vision loss vigabatrin is available only through a special restricted distribution program called SHARE, by calling 1-888-45-SHARE. Only prescribers and pharmacies registered with SHARE may prescribe and distribute vigabatrin. In addition, vigabatrin may be dispensed only to patients who are enrolled in and meet all conditions of SHARE.

Vigabatrin may be given without regard to meals.

Vigabatrin tablets and powder for oral solution are bioequivalent. Either tablet or powder can be used for CPS. Powder for oral solution should be used for IS. Tablets should not be used for IS because of difficulty in the administration of tablets to infants and young children.

Vigabatrin powder for oral solution should be mixed with water prior to administration.

Monitoring of vigabatrin plasma concentrations to optimize therapy is not helpful.

When vigabatrin is discontinued, the dose should be reduced gradually.

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