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Vigabatrin Dosage

Applies to the following strength(s): 500 mg

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Epilepsy

Children 10 to 16 years of age:
See Usual Pediatric Dose

17 years of age and older:
-Initial dose: 500 mg orally twice a day
-Titration: The total daily dose may be increased in 500 mg increments at weekly intervals depending on response
-Maintenance dose: 1500 mg orally twice a day
-Maximum dose: 3000 mg daily in 2 divided doses; a 6000 mg daily dose has not been shown to confer additional benefit compared to the 3000 mg daily dose and is associated with an increased incidence of adverse events

Comments:
-This drug can be taken with or without food.
-In clinical studies, this drug was tapered by decreasing the daily dose by 1000 mg/day on a weekly basis until discontinued.
-In patients with refractory complex partial seizures, this drug should be withdrawn if a substantial clinical benefit is not observed within 3 months of initiating treatment; if evidence of treatment failure becomes obvious earlier than 3 months, treatment should be discontinued at that time.

Use: 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 (this drug 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: 25 mg/kg twice daily
-Titration: 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 in 2 divided doses (75 mg/kg twice daily)

Comments:
-This drug can be taken with or without food.
-In clinical studies, this drug was tapered by decreasing the daily dose 25 to 50 mg/kg every 3 to 4 days.
-In patients with infantile spasms, this drug should be withdrawn if a substantial clinical benefit is not observed within 2 to 4 weeks of initiating treatment; if evidence of treatment failure becomes obvious earlier than 2 to 4 weeks, treatment should be discontinued at that time.

COMPLEX PARTIAL SEIZURES IN CHILDREN 10 TO 16 YEARS OF AGE:
-Body weight 25 to 60 kg:
Initial dose: 250 mg orally twice a day
Titration: The total daily dose may be increased in 500 mg increments at weekly intervals depending on response
Maintenance dose: 1000 mg orally twice a day
-Body weight greater than 60 kg:
Patients weighing more than 60 kg should be dosed according to adult recommendations

Comments:
-This drug can be taken with or without food.
-In clinical studies in pediatric patients with complex partial seizures, this drug was tapered by decreasing the daily dose by one-third every week for 3 weeks.
-In patients with refractory complex partial seizures, this drug should be withdrawn if a substantial clinical benefit is not observed within 3 months of initiating treatment; if evidence of treatment failure becomes obvious earlier than 3 months, treatment should be discontinued at that time.

Uses:
-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 risk of vision loss.
-For 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 (this drug 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 50 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 10 to 30 mL/min): Decrease dose by 75%

Liver Dose Adjustments

Data not available

Dose Adjustments

-This drug should be used at the lowest effective dose in order to achieve therapeutic efficacy and minimize adverse effects.
-Therapy should not be ceased abruptly; it is recommended that doses be gradually reduced and then withdrawn.
-Caution is recommended in the elderly; dose reductions and increased monitoring may be required.

Precautions

Because of the risk of permanent vision loss, the US FDA requires a Risk Evaluation and Mitigation Strategy (REMS) for vigabatrin called the SABRIL REMS Program. It includes elements to assure safe use and an implementation system.
Notable requirements of the SABRIL REMS Program include the following:
-Prescribers must be certified by enrolling in the program, agreeing to counsel patients on the risk of vision loss and the need for periodic monitoring of vision, and reporting any event suggestive of vision loss to Lundbeck.
-Patients must enroll in the program.
-Pharmacies must be certified and must only dispense to patients authorized to receive SABRIL.
Further information is available at www.SabrilREMS.com, or call 1-888-457-4273, and at http://www.accessdata.fda.gov/scripts/cder/rems/index.cfm.

US BOXED WARNINGS:
PERMANENT VISION LOSS:
-This drug can cause permanent bilateral concentric visual field constriction, including tunnel vision that can result in disability. In some cases, it also can damage the central retina and may decrease visual acuity.
-The onset of vision loss is unpredictable, and can occur within weeks of starting treatment or sooner, or at any time after starting treatment, even after months or years.
-Symptoms of vision loss are unlikely to be recognized by patients or caregivers before vision loss is severe. Vision loss of milder severity, while often unrecognized by the patient or caregiver, can still adversely affect function.
-The risk of vision loss increases with increasing dose and cumulative exposure, but there is no dose or exposure known to be free of risk of vision loss.
-Vision assessment is recommended at baseline (no later than 4 weeks after starting SABRIL), at least every 3 months during therapy, and about 3 to 6 months after the discontinuation of therapy.
-Once detected, vision loss is not reversible. It is expected that, even with frequent monitoring, some patients will develop severe vision loss.
-Consider drug discontinuation, balancing benefit and risk, if vision loss is documented.
-Risk of new or worsening vision loss continues as long as this drug is used. It is possible that vision loss can worsen despite discontinuation of therapy.
-Because of the risk of vision loss, therapy should be withdrawn from patients with refractory complex partial seizures who fail to show substantial clinical benefit within 3 months of initiation and within 2 to 4 weeks of initiation for patients with infantile spasms, or sooner if treatment failure becomes obvious. Patient response to and continued need for therapy should be periodically reassessed.
-This drug should not be used in patients with, or at high risk of, other types of irreversible vision loss unless the benefits of treatment clearly outweigh the risks.
-This drug should not be used with other drugs associated with serious adverse ophthalmic effects such as retinopathy or glaucoma unless the benefits clearly outweigh the risks.
-Use the lowest dosage and shortest exposure to this drug consistent with clinical objectives.

-Safety and efficacy have not been established in pediatric patients less than 10 years of age with refractory complex partial seizures.
-Safety and efficacy as monotherapy for pediatric patients with infantile spasms (1 month to 2 years of age) have been established.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available; isolated reports in patients with renal failure on hemodialysis reported a reduction in vigabatrin plasma concentrations by 40 to 60%.

Other Comments

Administration advice:
-This drug may be given with or without food.
-If a decision is made to discontinue therapy, the dose should be gradually reduced.

Reconstitution/preparation techniques:
-The powder for oral solution should be mixed with water prior to administration.
-Consult the manufacturer product information for reconstitution instructions.

General:
-Therapy should only be initiated by a specialist (in epileptology, neurology or pediatric neurology) and follow-up arranged under their supervision.
-Use the lowest dosage and shortest exposure consistent with clinical objectives.
-The dosing regimen depends on the indication, age group, weight, and dosage form (tablets or powder for oral solution).
-Tablets and powder for oral solution are bioequivalent. Either tablet or powder can be used for Refractory Complex Partial Seizures (CPS). Powder for oral solution should be used for Infantile Spasms (IS); tablets should not be used for IS because of difficulty in the administration of tablets to infants and young children.

Patient advice:
-Patients should be fully apprised of the risk of permanent vision loss.

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