Vigabatrin

1 INDICATIONS AND USAGE VIGADRONE is indicated for the treatment of: Refractory Complex Partial Seizures as adjunctive therapy in patients 2 years of age and older who have responded inadequately to several alternative treatments; VIGADRONE is not indicated as a first line agent ( 1.1 ) Infantile Spasms – monotherapy in infants 1 month to 2 years of age for whom the potential benefits outweigh the potential risk of vision loss ( 1.2 ) 1.1 Refractory Complex Partial Seizures (CPS) VIGADRONE is 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) ]. VIGADRONE is not indicated as a first line agent for complex partial seizures. 1.2 Infantile Spasms (IS) VIGADRONE 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) ].

12.1 Mechanism of Action The precise mechanism of vigabatrin's anti-seizure effect is unknown, but it is believed to be the result of its action as an irreversible inhibitor of γ-aminobutyric acid transaminase (GABA-T), the enzyme responsible for the metabolism of the inhibitory neurotransmitter GABA. This action results in increased levels of GABA in the central nervous system. No direct correlation between plasma concentration and efficacy has been established. The duration of drug effect is presumed to be dependent on the rate of enzyme re-synthesis rather than on the rate of elimination of the drug from the systemic circulation.

2 DOSAGE AND ADMINISTRATION Refractory Complex Partial Seizures Adults (17 years of age and older): Initiate at 1,000 mg/day (500 mg twice daily); increase total daily dose weekly in 500 mg/day increments, to the recommended dose of 3,000 mg/day (1,500 mg twice daily) ( 2.2 ) Pediatric (2 to 16 years of age): The recommended dosage is based on body weight and administered as two divided doses ( 2.2 ) The dosage may be increased in weekly intervals, depending on response ( 2.2 ) Dose patients weighing more than 60 kg according to adult recommendations ( 2.2 ) Infantile Spasms Initiate at a daily dose of 50 mg/kg (25 mg/kg twice daily); increase total daily dose every 3 days, in increments of 25 mg/kg/day to 50 mg/kg/day, up to a maximum daily dose of 150 mg/kg (75 mg/kg twice daily) ( 2.3 ) Renal Impairment : Dose adjustment recommended ( 2.4 , 8.5 , 8.6 ) 2.1 Important Dosing and Administration Instructions Dosing Use the lowest dosage and shortest exposure to VIGADRONE consistent with clinical objectives [see Warnings and Precautions (5.1) ]. The VIGADRONE 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 VIGADRONE plasma concentrations to optimize therapy is not helpful. Administration VIGADRONE tablets are given orally with or without food. If a decision is made to discontinue VIGADRONE, the dose should be gradually reduced [see Dosage and Administration (2.2 , 2.3) , 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 VIGADRONE 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 Patients weighing more than 60 kg should be dosed according to adult recommendations Body Weight [kg] Total Daily Administered in two divided doses. Starting Dose [mg/day] Total Daily Maintenance Dose Maintenance dose is based on 3,000 mg/day adult-equivalent 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 In patients with refractory complex partial seizures, VIGADRONE 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) ]. 2.3 Infantile Spasms The initial daily dosing is 50 mg/kg/day given in two divided doses (25 mg/kg twice daily); subsequent dosing can be titrated by 25 mg/kg/day to 50

6 ADVERSE REACTIONS The following serious and otherwise important adverse reactions are described elsewhere in labeling: Permanent Vision Loss [see BOXED WARNING , Warnings and Precautions (5.1) ] Magnetic Resonance Imaging (MRI) Abnormalities in Infants [see Warnings and Precautions (5.3) ] Neurotoxicity [see Warnings and Precautions (5.4) ] Suicidal Behavior and Ideation [see Warnings and Precautions (5.5) ] Withdrawal of Antiepileptic Drugs (AEDs) [see Warnings and Precautions (5.6) ] Anemia [see Warnings and Precautions (5.7) ] Somnolence and Fatigue [see Warnings and Precautions (5.8) ] Peripheral Neuropathy [see Warnings and Precautions (5.9) ] Weight Gain [see Warnings and Precautions (5.10) ] Edema [see Warnings and Precautions (5.11) ] Refractory Complex Partial Seizures Most common adverse reactions in controlled studies include (incidence ≥5% over placebo): Adults: blurred vision, somnolence, dizziness, abnormal coordination, tremor, and fatigue ( 6.1 ) Pediatric patients (3 to 16 years of age): weight gain ( 6.1 ) Infantile Spasms (incidence ˃5% and greater than on placebo) Somnolence, bronchitis, ear infection, and acute otitis media ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Upsher-Smith Laboratories, LLC at 1-855-899-9180 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In U.S. and primary non-U.S. clinical studies of 4,079 vigabatrin-treated patients, the most common (≥5%) adverse reactions associated with the use of vigabatrin in combination with other AEDs were headache, somnolence, fatigue, dizziness, convulsion, nasopharyngitis, weight gain, upper respiratory tract infection, visual field defect, depression, tremor, nystagmus, nausea, diarrhea, memory impairment, insomnia, irritability, abnormal coordination, blurred vision, diplopia, vomiting, influenza, pyrexia, and rash. The adverse reactions most commonly associated with vigabatrin treatment discontinuation in ≥1% of patients were convulsion and depression. In patients with infantile spasms, the adverse reactions most commonly associated with vigabatrin treatment discontinuation in ≥1% of patients were infections, status epilepticus, developmental coordination disorder, dystonia, hypotonia, hypertonia, weight gain, and insomnia. Refractory Complex Partial Seizures Adults Table 5 lists the adverse reactions that occurred in ≥2% and more than one patient per vigabatrin treated group and that occurred more frequently than in placebo patients from 2 U.S. adjunctive clinical studies of refractory CPS in adults. Table 5. Adverse Reactions in Pooled, Adjunctive Trials in Adults with Refractory Complex Partial Seizures Vigabatrin dosage (mg/day) Body System Adverse Reaction 3,000 [N=134] % 6,000 [N=43] % Placebo [N=135] % Ear Disorders Tinnitus 2 0 1 Vertigo 2 5 1 Eye Disorders Blurred vision 13 16 5 Diplopia 7 16 3 Asthenopia 2 2 0 Eye pain 0 5 0 Gastrointestinal Disorders Diarrhea 10 16 7 Nausea 10 2 8 Vomiting 7 9 6 Constipation 8 5 3 Upper abdominal pain 5 5 1 Dyspepsia 4 5 3 Stomach discomfort 4 2 1 Abdominal pain 3 2 1 Toothache 2 5 2 Abdominal distension 2 0 1 General Disorders Fatigue 23 40 16 Gait disturbance 6 12 7 Asthenia 5 7 1 Edema peripheral 5 7 1 Fever 4 7 3 Chest pain 1 5 1 Thirst 2 0 0 Malaise 0 5 0 Infections Nasopharyngitis 14 9 10 Upper respiratory tract infection 7 9 6 Influenza 5 7 4 Urinary tract infection 4 5 0 Bronchitis 0 5 1 Injury Contusion 3 5 2 Joint sprain 1 2 1 Muscle strain 1 2 1 Wound secretion 0 2 0 Metabolism and Nutrition Disorders Increased appetite 1 5 1 Weight gain 6 14 3 Musculoskeletal Disorders Arthralgia 10 5 3 Back pain 4 7 2 Pain in extremity 6 2 4 Myalgia 3 5 1 Muscle twitching 1 9 1 Muscle spasms 3 0 1 Nervous S

5 WARNINGS AND PRECAUTIONS Abnormal MRI signal changes and intramyelinic edema have been reported in some infants with Infantile Spasms receiving vigabatrin ( 5.3 , 5.4 ) Suicidal behavior and ideation: Antiepileptic drugs, including VIGADRONE, increase the risk of suicidal thoughts and behavior ( 5.5 ) Withdrawal of AEDs: Taper dose to avoid withdrawal seizures ( 5.6 ) Anemia: Monitor for symptoms of anemia ( 5.7 ) Somnolence and fatigue: Advise patients not to drive or operate machinery until they have gained sufficient experience on VIGADRONE ( 5.8 ) 5.1 Permanent Vision Loss VIGADRONE can cause permanent vision loss. Because of this risk and because, when it is effective, VIGADRONE provides an observable symptomatic benefit; patient response and continued need for treatment should be periodically assessed. Based upon adult studies, 30 percent or more of patients can be affected with bilateral concentric visual field constriction ranging in severity from mild to severe. Severe cases may be characterized by tunnel vision to within 10 degrees of visual fixation, which can result in disability. In some cases, VIGADRONE also can damage the central retina and may decrease visual acuity. Symptoms of vision loss from VIGADRONE 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. Because assessing vision may be difficult in infants and children, the frequency and extent of vision loss is poorly characterized in these patients. For this reason, the understanding of the risk is primarily based on the adult experience. The possibility that vision loss from vigabatrin may be more common, more severe, or have more severe functional consequences in infants and children than in adults cannot be excluded. The onset of vision loss from VIGADRONE is unpredictable and can occur within weeks of starting treatment or sooner, or at any time after starting treatment, even after months or years. 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. In patients with refractory complex partial seizures, VIGADRONE 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 Dosage and Administration (2.2) , Warnings and Precautions (5.6) ]. In patients with infantile spasms, VIGADRONE should be withdrawn if a substantial clinical benefit is not observed within 2 to 4 weeks. If, in the clinical judgment of the prescriber, evidence of treatment failure becomes obvious earlier than 2 to 4 weeks, treatment should be discontinued at that time [see Dosage and Administration (2.3) , Warnings and Precautions (5.6) ]. VIGADRONE 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. The interaction of other types of irreversible vision damage with vision damage from VIGADRONE has not been well-characterized but is likely adverse. VIGADRONE 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. Monitoring of Vision Monitoring of vision by an ophthalmic professional with expertise in visual field interpretation and the ability to perform dilated indirect ophthalmoscopy of the retina is recommended [see Warnings and Precautions (5.2) ]. Because vision testing in infants is difficult, vision loss may not be detected until it is severe. For patients receiving VIGADRONE, vision assessment is recommended at baseline (no later than 4 weeks after starting VIGADRONE), at least every 3 months wh

4 CONTRAINDICATIONS None. None ( 4 )

10 OVERDOSAGE 10.1 Signs, Symptoms, and Laboratory Findings of Overdosage Confirmed and/or suspected vigabatrin overdoses have been reported during clinical trials and in post marketing surveillance. No vigabatrin overdoses resulted in death. When reported, the vigabatrin dose ingested ranged from 3 g to 90 g, but most were between 7.5 g and 30 g. Nearly half the cases involved multiple drug ingestions including carbamazepine, barbiturates, benzodiazepines, lamotrigine, valproic acid, acetaminophen, and/or chlorpheniramine. Coma, unconsciousness, and/or drowsiness were described in the majority of cases of vigabatrin overdose. Other less commonly reported symptoms included vertigo, psychosis, apnea or respiratory depression, bradycardia, agitation, irritability, confusion, headache, hypotension, abnormal behavior, increased seizure activity, status epilepticus, and speech disorder. These symptoms resolved with supportive care. 10.2 Management of Overdosage There is no specific antidote for VIGADRONE overdose. Standard measures to remove unabsorbed drug should be used, including elimination by emesis or gastric lavage. Supportive measures should be employed, including monitoring of vital signs and observation of the clinical status of the patient. In an in vitro study, activated charcoal did not significantly adsorb vigabatrin. The effectiveness of hemodialysis in the treatment of VIGADRONE overdose is unknown. In isolated case reports in renal failure patients receiving therapeutic doses of vigabatrin, hemodialysis reduced vigabatrin plasma concentrations by 40% to 60%.