VIGABATRIN

VIGABATRIN- vigabatrin powder, for solution
Par Pharmaceutical, Inc.

WARNING: PERMANENT VISION LOSS

  • Vigabatrin can cause permanent bilateral concentric visual field constriction, including tunnel vision that can result in disability. In some cases, vigabatrin also can damage the central retina and may decrease visual acuity [see Warnings and Precautions (5.1)].
  • The onset of vision loss from vigabatrin 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 from vigabatrin 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 vigabatrin ), at least every 3 months during therapy, and about 3 to 6 months after the discontinuation of therapy.
  • Once detected, vision loss due to vigabatrin 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 vigabatrin is used. It is possible that vision loss can worsen despite discontinuation of vigabatrin .
  • Because of the risk of vision loss, vigabatrin should be withdrawn from patients with refractory complex partial seizures who fail to show substantial clinical benefit within 3 months of initiation and within 2-4 weeks of initiation for patients with infantile spasms, or sooner if treatment failure becomes obvious. Patient response to and continued need for vigabatrin should be periodically reassessed.
  • Vigabatrin 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.
  • Vigabatrin 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 vigabatrin consistent with clinical objectives [see Dosage and Administration (2.1)].

Because of the risk of permanent vision loss, vigabatrin is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) called the Vigabatrin REMS Program [see Warnings and Precautions (5.2)]. Further information is available at www.vigabatrinREMS.com or 1-866-244-8175.

1 INDICATIONS AND USAGE

1.1 Refractory Complex Partial Seizures (CPS)

Vigabatrin for oral solution is indicated as adjunctive therapy for adults and pediatric patients 10 years of age and older with refractory complex partial seizures who have inadequately responded to several alternative treatments and for whom the potential benefits outweigh the risk of vision loss [see Warnings and Precautions (5.1)]. Vigabatrin for oral solution is not indicated as a first line agent for complex partial seizures.

1.2 Infantile Spasms (IS)

Vigabatrin for oral solution is indicated as monotherapy for pediatric patients with infantile spasms 1 month to 2 years of age for whom the potential benefits outweigh the potential risk of vision loss [see Warnings and Precautions (5.1)].

2 DOSAGE AND ADMINISTRATION

2.1 Important Dosing and Administration Instructions

Dosing

Use the lowest dosage and shortest exposure to vigabatrin for oral solution consistent with clinical objectives [see Warnings and Precautions (5.1)].

The vigabatrin for oral solution dosing regimen depends on the indication, age group, weight, and dosage form (tablets or powder for oral solution) [see Dosage and Administration (2.2, 2.3)]. Patients with impaired renal function require dose adjustment [see Dosage and Administration (2.4)].

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

Administration

Vigabatrin for oral solution is given orally with or without food.

Vigabatrin for oral solution powder for oral solution should be mixed with water prior to administration [see Dosage and Administration (2.5)]. A calibrated measuring device is recommended to measure and deliver the prescribed dose accurately. A household teaspoon or tablespoon is not an adequate measuring device.

If a decision is made to discontinue vigabatrin for oral solution, the dose should be gradually reduced [see Dosage and Administration (2.2, 2.3) and Warnings and Precautions (5.6)].

2.2 Refractory Complex Partial Seizures

Adults (Patients 17 Years of Age and Older)

Treatment should be initiated at 1,000 mg/day (500 mg twice daily). Total daily dose may be increased in 500 mg increments at weekly intervals, depending on response. The recommended dose of vigabatrin for oral solution in adults is 3,000 mg/day (1,500 mg twice daily). A 6,000 mg/day dose has not been shown to confer additional benefit compared to the 3,000 mg/day dose and is associated with an increased incidence of adverse events.

In controlled clinical studies in adults with complex partial seizures, vigabatrin for oral solution was tapered by decreasing the daily dose 1,000 mg/day on a weekly basis until discontinued [see Warnings and Precautions (5.6)].

Pediatric (Patients 2 to 16 Years of Age)

The recommended dosage is based on body weight and administered as two divided doses, as shown in Table 1. The dosage may be increased in weekly intervals to the total daily maintenance dosage, depending on response.

Pediatric patients weighing more than 60 kg should be dosed according to adult recommendations.

Table 1. CPS Dosing Recommendations for Pediatric Patients Weighing 10 kg up to 60 kg††

Body Weight

[kg]

Total Daily*

Starting Dose

[mg/day]

Total Daily* Maintenance Dose [mg/day]

10 kg to 15 kg

350 mg

1050 mg

Greater than 15 kg to 20 kg

450 mg

1300 mg

Greater than 20 kg to 25 kg

500 mg

1500 mg

Greater than 25 kg to 60 kg

500 mg

2000 mg

* Administered in two divided doses.

Maintenance dose is based on 3,000 mg/day adult-equivalent dose

†† Patients weighing more than 60 kg should be dosed according to adult recommendations

In patients with refractory complex partial seizures, vigabatrin for oral solution should be withdrawn if a substantial clinical benefit is not observed within 3 months of initiating treatment. If, in the clinical judgment of the prescriber, evidence of treatment failure becomes obvious earlier than 3 months, treatment should be discontinued at that time [see Warnings and Precautions (5.1)].

In a controlled study in pediatric patients with complex partial seizures, vigabatrin for oral solution was tapered by decreasing the daily dose by one third every week for three weeks [see Warnings and Precautions (5.6)].

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