Vigabatrin

FDA Drug Information • Also known as: Sabril, Vigabatrin, Vigabatrin For Oral Solution, Vigadrone, Vigafyde, Vigpoder

Brand Names: Sabril, Vigabatrin, Vigabatrin For Oral Solution, Vigadrone, Vigafyde, Vigpoder
Dosage Form: POWDER
Product Type: BULK INGREDIENT

⚠ Boxed Warning (Black Box)

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 tablets. Because of the risk of vision loss, vigabatrin should be withdrawn from patients with refractory complex partial seizures who fail to show substantial clinical benefit within 3 months of initiation and within 2 to 4 weeks of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 tablets are 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. WARNING: PERMANENT VISION LOSS See full prescribing information for complete boxed warning. Vigabatrin can cause permanent bilateral concentric visual field constriction, including tunnel vision that can result in disability. In some cases, vigabatrin may also decrease visual acuity ( 5.1 ). Risk increases with increasing dose and cumulative exposure, but there is no dose or exposure to vigabatrin known to be free of risk of vision loss ( 5.1 ). Risk of new and worsening vision loss continues as long as vigabatrin is used, and possibly after discontinuing vigabatrin tablets ( 5.1 ). Baseline and periodic vision assessment is recommended for patients on vigabatrin. However, this assessment cannot always prevent vision damage ( 5.1 ). Vigabatrin tablets are available only through a restricted program called the Vigabatrin REMS Program ( 5.2 ).

Description

11 DESCRIPTION Vigabatrin USP is an oral antiepileptic drug and is available as a white to off-white film-coated tablet. The chemical name of vigabatrin, a racemate consisting of two enantiomers, is (±) 4-amino-5-hexenoic acid. The molecular formula is C 6 H 11 NO 2 and the molecular weight is 129.16. It has the following structural formula: Vigabatrin USP is a white or almost white powder which is freely soluble in water. The pH of a 1% aqueous solution is about 6.99. The n-octanol/pH 7.4 Buffer solution (50:50) partition coefficient of vigabatrin is about (-)0.49. Vigabatrin meting range is within the temperature interval of 168°C to 178°C. The dissociation constants (pKa) of vigabatrin is 9.67 at room temperature (25°C). Each vigabatrin tablet, USP contains 500 mg of vigabatrin. The inactive ingredients are colloidal silicon dioxide, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, povidone, sodium starch glycolate and titanium dioxide.

What Is Vigabatrin Used For?

1 INDICATIONS AND USAGE Vigabatrin tablets are 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; Vigabatrin tablets are 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) 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. 1.2 Infantile Spasms (IS) Vigabatrin tablets are 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 ) ]. 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. 1.2 Infantile Spasms (IS) Vigabatrin tablets are 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 ) ].

Dosage and Administration

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 vigabatrin tablets consistent with clinical objectives [ see Warnings and Precautions ( 5.1 ) ]. The vigabatrin tablets 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 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 , 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 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...

Side Effects (Adverse Reactions)

6 ADVERSE REACTIONS The following serious and otherwise important adverse reactions are described elsewhere in labeling: Permanent Vision Loss [ see BOXED WARNING and 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 Dr. Reddy’s Laboratories, Inc. at 1-888-375-3784 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) Vigabatrin dosage(mg/day) Vigabatrin dosage(mg/day) 3000 6000 Placebo Body System [N=134] [N=43] [N=135] Adverse Reaction % % % 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...

Drug Interactions

7 DRUG INTERACTIONS Decreased phenytoin plasma levels: dosage adjustment may be needed ( 7.1 ) 7.1 Antiepileptic Drugs Phenytoin Although phenytoin dose adjustments are not routinely required, dose adjustment of phenytoin should be considered if clinically indicated, since vigabatrin may cause a moderate reduction in total phenytoin plasma levels [ see Clinical Pharmacology ( 12.3 ) ]. Clonazepam Vigabatrin may moderately increase the C max of clonazepam resulting in an increase of clonazepam-associated adverse reactions [ see Clinical Pharmacology ( 12.3 ) ]. Other AEDs There are no clinically significant pharmacokinetic interactions between vigabatrin and either phenobarbital or sodium valproate. Based on population pharmacokinetics, carbamazepine, clorazepate, primidone, and sodium valproate appear to have no effect on plasma concentrations of vigabatrin [ see Clinical Pharmacology ( 12.3 ) ]. 7.2 Oral Contraceptives Vigabatrin is unlikely to affect the efficacy of steroid oral contraceptives [ see Clinical Pharmacology ( 12.3 ) ]. 7.3 Drug-Laboratory Test Interactions Vigabatrin decreases alanine transaminase (ALT) and aspartate transaminase (AST) plasma activity in up to 90% of patients. In some patients, these enzymes become undetectable. The suppression of ALT and AST activity by vigabatrin may preclude the use of these markers, especially ALT, to detect early hepatic injury. Vigabatrin may increase the amount of amino acids in the urine, possibly leading to a false positive test for certain rare genetic metabolic diseases (e.g., alpha aminoadipic aciduria). 7.1 Antiepileptic Drugs Phenytoin Although phenytoin dose adjustments are not routinely required, dose adjustment of phenytoin should be considered if clinically indicated, since vigabatrin may cause a moderate reduction in total phenytoin plasma levels [ see Clinical Pharmacology ( 12.3 ) ]. Clonazepam Vigabatrin may moderately increase the C max of clonazepam resulting in an increase of clonazepam-associated adverse reactions [ see Clinical Pharmacology ( 12.3 ) ]. Other AEDs There are no clinically significant pharmacokinetic interactions between vigabatrin and either phenobarbital or sodium valproate. Based on population pharmacokinetics, carbamazepine, clorazepate, primidone, and sodium valproate appear to have no effect on plasma concentrations of vigabatrin [ see Clinical Pharmacology ( 12.3 ) ]. 7.2 Oral Contraceptives Vigabatrin is unlikely to affect the efficacy of steroid oral contraceptives [ see Clinical Pharmacology ( 12.3 ) ]. 7.3 Drug-Laboratory Test Interactions Vigabatrin decreases alanine transaminase (ALT) and aspartate transaminase (AST) plasma activity in up to 90% of patients. In some patients, these enzymes become undetectable. The suppression of ALT and AST activity by vigabatrin may preclude the use of these markers, especially ALT, to detect early hepatic injury. Vigabatrin may increase the amount of amino acids in the urine, possibly leading to a false...

Contraindications

4 CONTRAINDICATIONS None. None ( 4 )

Pregnancy and Breastfeeding

8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to AEDs, including vigabatrin, during pregnancy. Encourage women who are taking vigabatrin during pregnancy to enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll-free number 1-888-233-2334 or visiting the website, http://www.aedpregnancyregistry.org/. This must be done by the patient herself. Risk Summary There are no adequate data on the developmental risk associated with the use of vigabatrin in pregnant women. Limited available data from case reports and cohort studies pertaining to vigabatrin use in pregnant women have not established a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes. However, based on animal data, vigabatrin use in pregnant women may result in fetal harm. When administered to pregnant animals, vigabatrin produced developmental toxicity, including an increase in fetal malformations and offspring neurobehavioral and neurohistopathological effects, at clinically relevant doses. In addition, developmental neurotoxicity was observed in rats treated with vigabatrin during a period of postnatal development corresponding to the third trimester of human pregnancy ( see Data ). In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Data Animal Data Administration of vigabatrin (oral doses of 50 to 200 mg/kg/day) to pregnant rabbits throughout the period of organogenesis was associated with an increased incidence of malformations (cleft palate) and embryofetal death; these findings were observed in two separate studies. The no-effect dose for adverse effects on embryofetal development in rabbits...

Overdosage

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 grams to 90 grams, but most were between 7.5 grams and 30 grams. 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 vigabatrin 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 vigabatrin 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%. 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 grams to 90 grams, but most were between 7.5 grams and 30 grams. Nearly half the cases involved...

How Supplied

16 HOW SUPPLIED/STORAGE AND HANDLING 16.1 How Supplied Vigabatrin tablets USP, 500 mg are white to off-white color, oval shape, film-coated tablets debossed with 'l l' on one side and 'break line' on other side. Bottles of 100 NDC 43598-651-01 16.2 Storage and Handling Store at 20°C to 25°C (68°F to 77°F). See USP Controlled Room Temperature. 16.1 How Supplied Vigabatrin tablets USP, 500 mg are white to off-white color, oval shape, film-coated tablets debossed with 'l l' on one side and 'break line' on other side. Bottles of 100 NDC 43598-651-01 16.2 Storage and Handling Store at 20°C to 25°C (68°F to 77°F). See USP Controlled Room Temperature.

About This Information

This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.

What are side effects?

Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.

What are drug interactions?

Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.