Vigabatrin

VIGABATRIN — vigabatrin tablet, film coated
Cadila Healthcare Limited

WARNING: PERMANENT VISION LOSS

  • Viga batrin 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  • Because of the risk of vision loss, vigabatrin should be withdrawn from patients with refractory complex partial seizures who fail to show substantial clinical benefit within 3 months of initiation and within 2 to 4 weeks of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 tablets are indicated as adjunctive therapy for adults and pediatric patients 2 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 tablets are not indicated as a first line agent for complex partial seizures.

2 DOSAGE AND ADMINISTRATION

2.1 Important Dosing and Administration Instructions

Dosing

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

The vigabatrin dosing regimen depends on the indication, age group, weight, and dosage form (tablets or for oral solution) [see Dosage and Administration (2.2)]. 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 tablets are given orally with or without food.

If a decision is made to discontinue vigabatrin tablets, the dose should be gradually reduced [see Dosage and Administration (2.2) 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 tablets 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 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 1,050 mg
Greater than 15 kg to 20 kg 450 mg 1,300 mg
Greater than 20 kg to 25 kg 500 mg 1,500 mg
Greater than 25 kg to 60 kg 500 mg 2,000 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 tablets 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 was tapered by decreasing the daily dose by one third every week for three weeks [see Warnings and Precautions (5.6)].

2.4 Patients with Renal Impairment

Vigabatrin is primarily eliminated through the kidney.

Adult and pediatric patients 2 years and older

  • Mild renal impairment (CLcr >50 to 80 mL/min): dose should be decreased by 25%
  • Moderate renal impairment (CLcr >30 to 50 mL/min): dose should be decreased by 50%
  • Severe renal impairment (CLcr >10 to 30 mL/min): dose should be decreased by 75%

CLcr in mL/min may be estimated from serum creatinine (mg/dL) using the following formulas:

  • Patients 2 to <12 years old: CLcr (mL/min/1.73 m2) = (K × Ht) / Scr height (Ht) in cm; serum creatinine (Scr) in mg/dL K (proportionality constant): Female Child (<12 years): K=0.55; Male Child (<12 years): K=0.70
  • Adult and pediatric patients 12 years or older: CLcr (mL/min) = [140-age (years)] × weight (kg) /[72 × serum creatinine (mg /dL)] (× 0.85 for female patients)

The effect of dialysis on vigabatrin clearance has not been adequately studied [see Clinical Pharmacology (12.3) and Use in Specific Populations (8.6)].

All MedLibrary.org resources are included in as near-original form as possible, meaning that the information from the original provider has been rendered here with only typographical or stylistic modifications and not with any substantive alterations of content, meaning or intent.

This site is provided for educational and informational purposes only, in accordance with our Terms of Use, and is not intended as a substitute for the advice of a medical doctor, nurse, nurse practitioner or other qualified health professional.

Privacy Policy | Copyright © 2022. All Rights Reserved.