ives [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).

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) ] .

ases may be characterized by tunnel vision to within 10 degrees of visual fixation, which can result in disability. in some cases, vigabatrin also can damage the central retina and may decrease visual acuity. 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. 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 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. 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 in patients with refractory complex partial seizures, vigabatrin should be withdrawn if a substantial clinical benefit is not observed within 3 months of initiating treatment.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) and warnings and precautions (5.6) ] . in patients with infantile spasms, vigabatrin 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) and warnings and precautions (5.6) ] . 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. the interaction of other types of irreversible vision damage with vision damage from vigabatrin has not been well-characterized, but is likely adverse. 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. 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 vigabatrin, vision assessment is recommended at baseline (no later than 4 weeks after starting vigabatrin), at least every 3 months while on therapy, and about 3 to 6 months after the discontinuation of therapy. the diagnostic approach should be individualized for the patient and clinical situation. in adults and cooperative pediatric patients, perimetry is recommended, preferably by automated threshold visual field testing. additional testing may also include electrophysiology (e.g., electroretinography [erg]), retinal imaging (e.g., optical coherence tomography [oct]), and/or other methods appropriate for the patient. in patients who cannot be tested, treatment may continue according to clinical judgment, with appropriate patient counseling. because of variability, results from ophthalmic monitoring must be interpreted with caution, and repeat assessment is recommended if results are abnormal or uninterpretable. repeat assessment in the first few weeks of treatment is recommended to establish if, and to what degree, reproducible results can be obtained, and to guide selection of appropriate ongoing monitoring for the patient. the onset and progression of vision loss from vigabatrin is unpredictable, and it may occur or worsen precipitously between assessments. once detected, vision loss due to vigabatrin is not reversible. it is expected that even with frequent monitoring, some vigabatrin patients will develop severe vision loss. consider drug discontinuation, balancing benefit and risk, if vision loss is documented. it is possible that vision loss can worsen despite discontinuation of vigabatrin. 5.2 vigabatrin rems program vigabatrin is available only through a restricted distribution program called the vigabatrin rems program, because of the risk of permanent vision loss. notable requirements of the vigabatrin 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 teva pharmaceuticals usa, inc. patients must enroll in the program. pharmacies must be certified and must only dispense to patients authorized to receive vigabatrin. further information is available at www.vigabatrinrems.com , or call 1-866-244-8175. 5.3 magnetic resonance imaging (mri) abnormalities in infants abnormal mri signal changes characterized by increased t2 signal and restricted diffusion in a symmetric pattern involving the thalamus, basal ganglia, brain stem, and cerebellum have been observed in some infants treated with vigabatrin. in a retrospective epidemiologic study in infants with infantile spasms (n=205), the prevalence of mri changes was 22% in vigabatrin-treated patients versus 4% in patients treated with other therapies. in this study, in postmarketing experience, and in published literature reports, these changes generally resolved with discontinuation of treatment. in a few patients, the lesion resolved despite continued use. it has been reported that some infants exhibited coincident motor abnormalities, but no causal relationship has been established and the potential for long-term clinical sequelae has not been adequately studied. neurotoxicity (brain histopathology and neurobehavioral abnormalities) was observed in rats exposed to vigabatrin during late gestation and the neonatal and juvenile periods of development, and brain histopathological changes were observed in dogs exposed to vigabatrin during the juvenile period of development. the relationship between these findings and the abnormal mri findings in infants treated with vigabatrin for infantile spasms is unknown [see warnings and precautions (5.4) and use in specific populations (8.1) ] . the specific pattern of signal changes observed in patients 6 years and younger was not observed in older pediatric and adult patients treated with vigabatrin. in a blinded review of mri images obtained in prospective clinical trials in patients with refractory complex partial seizures (cps) 3 years and older (n=656), no difference was observed in anatomic distribution or prevalence of mri signal changes between vigabatrin treated and placebo treated patients. in the postmarketing setting, mri changes have also been reported in patients 6 years of age and younger being treated for refractory cps. for adults treated with vigabatrin, routine mri surveillance is unnecessary as there is no evidence that vigabatrin causes mri changes in this population. 5.4 neurotoxicity intramyelinic edema (ime) has been reported in postmortem examination of infants being treated for infantile spasms with vigabatrin. abnormal mri signal changes characterized by increased t2 signal and restricted diffusion in a symmetric pattern involving the thalamus, basal ganglia, brain stem, and cerebellum have also been observed in some infants treated for is with vigabatrin. studies of the effects of vigabatrin on mri and evoked potentials (ep) in adult epilepsy patients have demonstrated no clear-cut abnormalities [see warnings and precautions (5.3 )] . vacuolation, characterized by fluid accumulation and separation of the outer layers of myelin, has been observed in brain white matter tracts in adult and juvenile rats and adult mice, dogs, and possibly monkeys following administration of vigabatrin. this lesion, referred to as intramyelinic edema (ime), was seen in animals at doses within the human therapeutic range. a no-effect dose was not established in rodents or dogs. in the rat and dog, vacuolation was reversible following discontinuation of vigabatrin treatment, but, in the rat, pathologic changes consisting of swollen or degenerating axons, mineralization, and gliosis were seen in brain areas in which vacuolation had been previously observed. vacuolation in adult animals was correlated with alterations in mri and changes in visual and somatosensory ep. administration of vigabatrin to rats during the neonatal and juvenile periods of development produced vacuolar changes in the brain gray matter (including the thalamus, midbrain, deep cerebellar nuclei, substantia nigra, hippocampus, and forebrain) which are considered distinct from the ime observed in vigabatrin treated adult animals. decreased myelination and evidence of oligodendrocyte injury were additional findings in the brains of vigabatrin-treated rats. an increase in apoptosis was seen in some brain regions following vigabatrin exposure during the early postnatal period. long-term neurobehavioral abnormalities (convulsions, neuromotor impairment, learning deficits) were also observed following vigabatrin treatment of young rats. administration of vigabatrin to juvenile dogs produced vacuolar changes in the brain gray matter (including the septal nuclei, hippocampus, hypothalamus, thalamus, cerebellum, and globus pallidus). neurobehavioral effects of vigabatrin were not assessed in the juvenile dog. these effects in young animals occurred at doses lower than those producing neurotoxicity in adult animals and were associated with plasma vigabatrin levels substantially lower than those achieved clinically in infants and children [see use in specific populations (8.1 , 8.4) ] . in a published study, vigabatrin (200 mg/kg/day and 400 mg/kg/day) induced apoptotic neurodegeneration in the brain of young rats when administered by intraperitoneal injection on postnatal days 5 to 7. administration of vigabatrin to female rats during pregnancy and lactation at doses below those used clinically resulted in hippocampal vacuolation and convulsions in the mature offspring. 5.5 suicidal behavior and ideation antiepileptic drugs (aeds), including vigabatrin, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. patients treated with any aed for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. pooled analyses of 199 placebo-controlled clinical trials (mono- and adjunctive therapy) of 11 different aeds showed that patients randomized to one of the aeds had approximately twice the risk (adjusted relative risk 1.8, 95% ci: 1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. in these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 aed treated patients was 0.43%, compared to 0.24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. there were four suicides in drug treated patients in the trials and none in placebo treated patients, but the number is too small to allow any conclusion about drug effect on suicide. the increased risk of suicidal thoughts or behavior with aeds was observed as early as one week after starting drug treatment with aeds and persisted for the duration of treatment assessed. because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed. the risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. the finding of increased risk with aeds of varying mechanisms of action and across a range of indications suggests that the risk applies to all aeds used for any indication. the risk did not vary substantially by age (5 to 100 years) in the clinical trials analyzed. table 4 shows absolute and relative risk by indication for all evaluated aeds. table 4. risk by indication for antiepileptic drugs in the pooled analysis indication placebo patients with events per 1,000 patients drug patients with events per 1,000 patients relative risk: incidence of drug events in drug patients/incidence in placebo patients risk difference: additional drug patients with events per 1,000 patients epilepsy 1.0 3.4 3.5 2.4 psychiatric 5.7 8.5 1.5 2.9 other 1.0 1.8 1.9 0.9 total 2.4 4.3 1.8 1.9 the relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications. anyone considering prescribing vigabatrin or any other aed must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. epilepsy and many other illnesses for which aeds are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated. patients, their caregivers, and families should be informed that aeds increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. behaviors of concern should be reported immediately to healthcare providers. 5.6 withdrawal of antiepileptic drugs (aeds) as with all aeds, vigabatrin should be withdrawn gradually. however, if withdrawal is needed because of a serious adverse event, rapid discontinuation can be considered. patients and caregivers should be told not to suddenly discontinue vigabatrin therapy. 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. 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. in a controlled clinical study in patients with infantile spasms, vigabatrin was tapered by decreasing the daily dose at a rate of 25 mg/kg to 50 mg/kg every 3 to 4 days. 5.7 anemia in north american controlled trials in adults, 6% of patients (16/280) receiving vigabatrin and 2% of patients (3/188) receiving placebo had adverse events of anemia and/or met criteria for potentially clinically important hematology changes involving hemoglobin, hematocrit, and/or rbc indices. across u.s. controlled trials, there were mean decreases in hemoglobin of about 3% and 0% in vigabatrin and placebo treated patients, respectively, and a mean decrease in hematocrit of about 1% in vigabatrin treated patients compared to a mean gain of about 1% in patients treated with placebo. in controlled and open-label epilepsy trials in adults and pediatric patients, 3 vigabatrin patients (0.06%, 3/4,855) discontinued for anemia and 2 vigabatrin patients experienced unexplained declines in hemoglobin to below 8 g/dl and/or hematocrit below 24%. 5.8 somnolence and fatigue vigabatrin causes somnolence and fatigue. patients should be advised not to drive a car or operate other complex machinery until they are familiar with the effects of vigabatrin on their ability to perform such activities. pooled data from two vigabatrin controlled trials in adults demonstrated that 24% (54/222) of vigabatrin patients experienced somnolence compared to 10% (14/135) of placebo patients. in those same studies, 28% of vigabatrin patients experienced fatigue compared to 15% (20/135) of placebo patients. almost 1% of vigabatrin patients discontinued from clinical trials for somnolence and almost 1% discontinued for fatigue. pooled data from three vigabatrin controlled trials in pediatric patients demonstrated that 6% (10/165) of vigabatrin patients experienced somnolence compared to 5% (5/104) of placebo patients. in those same studies, 10% (17/165) of vigabatrin patients experienced fatigue compared to 7% (7/104) of placebo patients. no vigabatrin patients discontinued from clinical trials due to somnolence or fatigue. 5.9 peripheral neuropathy vigabatrin causes symptoms of peripheral neuropathy in adults. pediatric clinical trials were not designed to assess symptoms of peripheral neuropathy, but observed incidence of symptoms based on pooled data from controlled pediatric studies appeared similar for pediatric patients on vigabatrin and placebo. in a pool of north american controlled and uncontrolled epilepsy studies, 4.2% (19/457) of vigabatrin patients developed signs and/or symptoms of peripheral neuropathy. in the subset of north american placebo-controlled epilepsy trials, 1.4% (4/280) of vigabatrin treated patients and no (0/188) placebo patients developed signs and/or symptoms of peripheral neuropathy. initial manifestations of peripheral neuropathy in these trials included, in some combination, symptoms of numbness or tingling in the toes or feet, signs of reduced distal lower limb vibration or position sensation, or progressive loss of reflexes, starting at the ankles. clinical studies in the development program were not designed to investigate peripheral neuropathy systematically and did not include nerve conduction studies, quantitative sensory testing, or skin or nerve biopsy. there is insufficient evidence to determine if development of these signs and symptoms was related to duration of vigabatrin treatment, cumulative dose, or if the findings of peripheral neuropathy were completely reversible upon discontinuation of vigabatrin. 5.10 weight gain vigabatrin causes weight gain in adult and pediatric patients. data pooled from randomized controlled trials in adults found that 17% (77/443) of vigabatrin patients versus 8% (22/275) of placebo patients gained ?7% of baseline body weight. in these same trials, the mean weight change among vigabatrin patients was 3.5 kg compared to 1.6 kg for placebo patients. data pooled from randomized controlled trials in pediatric patients with refractory complex partial seizures found that 47% (77/163) of vigabatrin patients versus 19% (19/102) of placebo patients gained ?7% of baseline body weight. in all epilepsy trials, 0.6% (31/4,855) of vigabatrin patients discontinued for weight gain. the long term effects of vigabatrin related weight gain are not known. weight gain was not related to the occurrence of edema. 5.11 edema vigabatrin causes edema in adults. pediatric clinical trials were not designed to assess edema, but observed incidence of edema-based pooled data from controlled pediatric studies appeared similar for pediatric patients on vigabatrin and placebo. pooled data from controlled trials demonstrated increased risk among vigabatrin patients compared to placebo patients for peripheral edema (vigabatrin 2%, placebo 1%), and edema (vigabatrin 1%, placebo 0%). in these studies, one vigabatrin and no placebo patients discontinued for an edema related ae. in adults, there was no apparent association between edema and cardiovascular adverse events such as hypertension or congestive heart failure. edema was not associated with laboratory changes suggestive of deterioration in renal or hepatic function.

on consistent with clinical objectives [see warnings and precautions (5.1) ] . the vigabatrin dosing regimen depends on the indication, age group, and weight [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 is given orally with or without food. vigabatrin 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, 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 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 †† total daily * total daily * body weight starting dose maintenance dose † [kg] [mg/day] [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 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 mg/kg/day increments every 3 days, up to a maximum of 150 mg/kg/day given in 2 divided doses (75 mg/kg twice daily) [see use in specific populations (8.4) ] . table 2 provides the volume of the 50 mg/ml dosing solution that should be administered as individual doses in infants of various weights. table 2. infant dosing table weight [kg] starting dose 50 mg/kg/day maximum dose 150 mg/kg/day 3 1.5 ml twice daily 4.5 ml twice daily 4 2 ml twice daily 6 ml twice daily 5 2.5 ml twice daily 7.5 ml twice daily 6 3 ml twice daily 9 ml twice daily 7 3.5 ml twice daily 10.5 ml twice daily 8 4 ml twice daily 12 ml twice daily 9 4.5 ml twice daily 13.5 ml twice daily 10 5 ml twice daily 15 ml twice daily 11 5.5 ml twice daily 16.5 ml twice daily 12 6 ml twice daily 18 ml twice daily 13 6.5 ml twice daily 19.5 ml twice daily 14 7 ml twice daily 21 ml twice daily 15 7.5 ml twice daily 22.5 ml twice daily 16 8 ml twice daily 24 ml twice daily in patients with infantile spasms, vigabatrin 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 warnings and precautions (5.1) ] . in a controlled clinical study in patients with infantile spasms, vigabatrin was tapered by decreasing the daily dose at a rate of 25 mg/kg to 50 mg/kg every 3 to 4 days [see warnings and precautions (5.6) ] . 2.4 patients with renal impairment vigabatrin is primarily eliminated through the kidney. infants information about how to adjust the dose in infants with renal impairment is unavailable. 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 m 2 ) = (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) ] . 2.5 preparation and administration instructions for vigabatrin for oral solution if using vigabatrin for oral solution, physicians should review and discuss the medication guide and instructions for mixing and giving vigabatrin with the patient or caregiver(s). physicians should confirm that patients or caregiver(s) understand how to mix vigabatrin powder with water and administer the correct daily dose. empty the entire contents of each 500 mg packet into a clean cup, and dissolve in 10 ml of cold or room temperature water per packet. administer the resulting solution using the 3 ml or 10 ml oral syringe supplied with the medication. the concentration of the final solution is 50 mg/ml. table 3 below describes how many packets and how many milliliters (ml) of water will be needed to prepare each individual dose. the concentration after reconstitution is 50 mg/ml. table 3. number of vigabatrin packets and ml of water needed for each individual dose individual dose [mg] total number of total ml of water [given twice daily] vigabatrin packets required for dissolving 0 to 500 1 packet 10 ml 501 to 1,000 2 packets 20 ml 1,001 to 1,500 3 packets 30 ml discard the resulting solution if it is not clear (or free of particles) and colorless. each individual dose should be prepared and used immediately. discard any unused portion of the solution after administering the correct dose.

(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 teva at 1-888-838-2872 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 ) 3,000 6,000 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 extremity 6 2 4 myalgia 3 5 1 muscle twitching 1 9 1 muscle spasms 3 0 1 nervous system disorders headache 33 26 31 somnolence 22 26 13 dizziness 24 26 17 nystagmus 13 19 9 tremor 15 16 8 memory impairment 7 16 3 abnormal coordination 7 16 2 disturbance in attention 9 0 1 sensory disturbance 4 7 2 hyporeflexia 4 5 1 paraesthesia 7 2 1 lethargy 4 7 2 hyperreflexia 4 2 3 hypoaesthesia 4 5 1 sedation 4 0 0 status epilepticus 2 5 0 dysarthria 2 2 1 postictal state 2 0 1 sensory loss 0 5 0 psychiatric disorders irritability 7 23 7 depression 6 14 3 confusional state 4 14 1 anxiety 4 0 3 depressed mood 5 0 1 abnormal thinking 3 7 0 abnormal behavior 3 5 1 expressive language disorder 1 7 1 nervousness 2 5 2 abnormal dreams 1 5 1 reproductive system dysmenorrhea 9 5 3 erectile dysfunction 0 5 0 respiratory and thoracic disorders pharyngolaryngeal pain 7 14 5 cough 2 14 7 pulmonary congestion 0 5 1 sinus headache 6 2 1 skin and subcutaneous tissue disorders rash 4 5 4 pediatrics 2 to 16 years of age table 6 lists adverse reactions from controlled clinical studies of pediatric patients receiving vigabatrin or placebo as adjunctive therapy for refractory complex partial seizures. adverse reactions that are listed occurred in at least 2% of vigabatrin treated patients and more frequently than placebo. the median vigabatrin dose was 49.4 mg/kg (range of 8.0 mg/kg to 105.9 mg/kg). table 6. adverse reactions in pooled, adjunctive trials in pediatric patients 3 to 16 years of age with refractory complex partial seizures all vigabatrin placebo body system [n=165] [n=104] adverse reaction % % eye disorders diplopia 3 2 blurred vision 2 0 gastrointestinal disorders upper abdominal pain 4 3 constipation 2 1 general disorders fatigue 10 7 infections and infestations upper respiratory tract infection 15 11 influenza 7 3 otitis media 6 4 streptococcal pharyngitis 4 3 viral gastroenteritis 2 0 investigations weight gain 15 2 nervous system disorders somnolence 6 5 nystagmus 4 3 tremor 4 2 status epilepticus 2 1 psychiatric disorders abnormal behavior 7 6 aggression 6 2 disorientation 3 0 safety of vigabatrin for the treatment of refractory cps in patients 2 years of age is expected to be similar to pediatric patients 3 to 16 years of age. infantile spasms in a randomized, placebo-controlled is study with a 5 day double-blind treatment phase (n=40), the adverse reactions that occurred in >5% of patients receiving vigabatrin and that occurred more frequently than in placebo patients were somnolence (vigabatrin 45%, placebo 30%), bronchitis (vigabatrin 30%, placebo 15%), ear infection (vigabatrin 10%, placebo 5%), and acute otitis media (vigabatrin 10%, placebo 0%). in a dose response study of low-dose (18 to 36 mg/kg/day) versus high-dose (100 to 148 mg/kg/day) vigabatrin, no clear correlation between dose and incidence of adverse reactions was observed. the adverse reactions (?5% in either dose group) are summarized in table 7. table 7. adverse reactions in a placebo-controlled trial in patients with infantile spasms vigabatrin vigabatrin low dose high dose body system [n=114] [n=108] adverse reaction % % eye disorders (other than field or acuity changes) strabismus 5 5 conjunctivitis 5 2 gastrointestinal disorders vomiting 14 20 constipation 14 12 diarrhea 13 12 general disorders fever 29 19 infections upper respiratory tract infection 51 46 otitis media 44 30 viral infection 20 19 pneumonia 13 11 candidiasis 8 3 ear infection 7 14 gastroenteritis viral 6 5 sinusitis 5 9 urinary tract infection 5 6 influenza 5 3 croup infectious 5 1 metabolism & nutrition disorders decreased appetite 9 7 nervous system disorders sedation 19 17 somnolence 17 19 status epilepticus 6 4 lethargy 5 7 convulsion 4 7 hypotonia 4 6 psychiatric disorders irritability 16 23 insomnia 10 12 respiratory disorders nasal congestion 13 4 cough 3 8 skin and subcutaneous tissue disorders rash 8 11 6.2 postmarketing experience the following adverse reactions have been identified during postapproval use of vigabatrin. because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. adverse reactions are categorized by system organ class. birth defects: congenital cardiac defects, congenital external ear anomaly, congenital hemangioma, congenital hydronephrosis, congenital male genital malformation, congenital oral malformation, congenital vesicoureteric reflux, dentofacial anomaly, dysmorphism, fetal anticonvulsant syndrome, hamartomas, hip dysplasia, limb malformation, limb reduction defect, low set ears, renal aplasia, retinitis pigmentosa, supernumerary nipple, talipes ear disorders: deafness endocrine disorders: delayed puberty gastrointestinal disorders: gastrointestinal hemorrhage, esophagitis general disorders: developmental delay, facial edema, malignant hyperthermia, multi-organ failure hepatobiliary disorders: cholestasis nervous system disorders: dystonia, encephalopathy, hypertonia, hypotonia, muscle spasticity, myoclonus, optic neuritis, dyskinesia psychiatric disorders: acute psychosis, apathy, delirium, hypomania, neonatal agitation, psychotic disorder respiratory disorders: laryngeal edema, pulmonary embolism, respiratory failure, stridor skin and subcutaneous tissue disorders: angioedema, maculo-papular rash, pruritus, stevens-johnson syndrome (sjs), toxic epidermal necrolysis (ten), alopecia

ives [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).

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 mg/kg 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 (100 mg/kg/day) is approximately 1/2 the maximum recommended human dose (mrhd) of 3 g/day on a body surface area (mg/m 2 ) basis. in rats, oral administration of vigabatrin (50, 100, or 150 mg/kg/day) throughout organogenesis resulted in decreased fetal body weights and increased incidences of fetal anatomic variations. the no-effect dose for adverse effects on embryo-fetal development in rats (50 mg/kg/day) is approximately 1/5 the mrhd on a mg/m 2 basis. oral administration of vigabatrin (50, 100, 150 mg/kg/day) to rats from the latter part of pregnancy through weaning produced long-term neurohistopathological (hippocampal vacuolation) and neurobehavioral (convulsions) abnormalities in the offspring. a no-effect dose for developmental neurotoxicity in rats was not established; the low-effect dose (50 mg/kg/day) is approximately 1/5 the mrhd on a mg/m 2 basis. in a published study, vigabatrin (300 mg/kg or 450 mg/kg) was administered by intraperitoneal injection to a mutant mouse strain on a single day during organogenesis (day 7, 8, 9, 10, 11, or 12). an increase in fetal malformations (including cleft palate) was observed at both doses. oral administration of vigabatrin (5 mg/kg, 15 mg/kg, or 50 mg/kg/day) to young rats during the neonatal and juvenile periods of development (postnatal days 4 to 65) produced neurobehavioral (convulsions, neuromotor impairment, learning deficits) and neurohistopathological (brain vacuolation, decreased myelination, and retinal dysplasia) abnormalities in treated animals. the early postnatal period in rats is generally thought to correspond to late pregnancy in humans in terms of brain development. the no-effect dose for developmental neurotoxicity in juvenile rats (5 mg/kg/day) was associated with plasma vigabatrin exposures (auc) less than 1/30 of those measured in pediatric patients receiving an oral dose of 50 mg/kg. 8.2 lactation risk summary vigabatrin is excreted in human milk. the effects of vigabatrin on the breastfed infant and on milk production are unknown. because of the potential for serious adverse reactions from vigabatrin in nursing infants, breastfeeding is not recommended. if exposing a breastfed infant to vigabatrin, observe for any potential adverse effects [see warnings and precautions ( 5.1 , 5.3 , 5.4 , 5.8 )] . 8.4 pediatric use the safety and effectiveness of vigabatrin as adjunctive treatment of refractory complex partial seizures in pediatric patients 2 to 16 years of age have been established and is supported by three double-blind, placebo-controlled studies in patients 3 to 16 years of age, adequate and well-controlled studies in adult patients, pharmacokinetic data from patients 2 years of age and older, and additional safety information in patients 2 years of age [see clinical pharmacology (12.3) and clinical studies (14.1) ] . the dosing recommendation in this population varies according to age group and is weight-based [see dosage and administration (2.2) ] . adverse reactions in this pediatric population are similar to those observed in the adult population [see adverse reactions (6.1) ] . safety and effectiveness as adjunctive treatment of refractory complex partial seizures in pediatric patients below the age of 2 and as monotherapy for the treatment of infantile spasms in pediatric patients below the age of 1 month have not been established. the safety and effectiveness of vigabatrin as monotherapy for pediatric patients with infantile spasms (1 month to 2 years of age) have been established [see dosage and administration (2.3) and clinical studies (14.2)] . duration of therapy for infantile spasms was evaluated in a post hoc analysis of a canadian pediatric epilepsy network (cpen) study of developmental outcomes in infantile spasms patients. this analysis suggests that a total duration of 6 months of vigabatrin therapy is adequate for the treatment of infantile spasms. however, prescribers must use their clinical judgment as to the most appropriate duration of use [see clinical studies (14.2)] . abnormal mri signal changes and intramyelinic edema (ime) in infants and young children being treated with vigabatrin have been observed [see warnings and precautions ( 5.3 , 5.4 )] . juvenile animal toxicity data oral administration of vigabatrin (5, 15, or 50 mg/kg/day) to young rats during the neonatal and juvenile periods of development (postnatal days 4 to 65) produced neurobehavioral (convulsions, neuromotor impairment, learning deficits) and neurohistopathological (brain gray matter vacuolation, decreased myelination, and retinal dysplasia) abnormalities. the no-effect dose for developmental neurotoxicity in juvenile rats (the lowest dose tested) was associated with plasma vigabatrin exposures (auc) substantially less than those measured in pediatric patients at recommended doses. in dogs, oral administration of vigabatrin (30 mg/kg or 100 mg/kg/day) during selected periods of juvenile development (postnatal days 22 to 112) produced neurohistopathological abnormalities (brain gray matter vacuolation). neurobehavioral effects of vigabatrin were not assessed in the juvenile dog. a no-effect dose for neurohistopathology was not established in juvenile dogs; the lowest effect dose (30 mg/kg/day) was associated with plasma vigabatrin exposures lower than those measured in pediatric patients at recommended doses [see warnings and precautions (5.4) ] . 8.5 geriatric use clinical studies of vigabatrin did not include sufficient numbers of patients aged 65 and over to determine whether they responded differently from younger patients. vigabatrin is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. oral administration of a single dose of 1.5 g of vigabatrin to elderly (?65 years) patients with reduced creatinine clearance (<50 ml/min) was associated with moderate to severe sedation and confusion in 4 of 5 patients, lasting up to 5 days. the renal clearance of vigabatrin was 36% lower in healthy elderly subjects (?65 years) than in young healthy males. adjustment of dose or frequency of administration should be considered. such patients may respond to a lower maintenance dose [see dosage and administration (2.4) and clinical pharmacology (12.3) ] . other reported clinical experience has not identified differences in responses between the elderly and younger patients. 8.6 renal impairment dose adjustment, including initiating treatment with a lower dose, is necessary in pediatric patients 2 years of age and older and adults with mild (creatinine clearance >50 ml/min to 80 ml/min), moderate (creatinine clearance >30 to 50 ml/min) and severe (creatinine clearance >10 ml/min to 30 ml/min) renal impairment [see dosage and administration (2.4) and clinical pharmacology (12.3) ] .

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 mg/kg 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 (100 mg/kg/day) is approximately 1/2 the maximum recommended human dose (mrhd) of 3 g/day on a body surface area (mg/m 2 ) basis. in rats, oral administration of vigabatrin (50, 100, or 150 mg/kg/day) throughout organogenesis resulted in decreased fetal body weights and increased incidences of fetal anatomic variations. the no-effect dose for adverse effects on embryo-fetal development in rats (50 mg/kg/day) is approximately 1/5 the mrhd on a mg/m 2 basis. oral administration of vigabatrin (50, 100, 150 mg/kg/day) to rats from the latter part of pregnancy through weaning produced long-term neurohistopathological (hippocampal vacuolation) and neurobehavioral (convulsions) abnormalities in the offspring. a no-effect dose for developmental neurotoxicity in rats was not established; the low-effect dose (50 mg/kg/day) is approximately 1/5 the mrhd on a mg/m 2 basis. in a published study, vigabatrin (300 mg/kg or 450 mg/kg) was administered by intraperitoneal injection to a mutant mouse strain on a single day during organogenesis (day 7, 8, 9, 10, 11, or 12). an increase in fetal malformations (including cleft palate) was observed at both doses. oral administration of vigabatrin (5 mg/kg, 15 mg/kg, or 50 mg/kg/day) to young rats during the neonatal and juvenile periods of development (postnatal days 4 to 65) produced neurobehavioral (convulsions, neuromotor impairment, learning deficits) and neurohistopathological (brain vacuolation, decreased myelination, and retinal dysplasia) abnormalities in treated animals. the early postnatal period in rats is generally thought to correspond to late pregnancy in humans in terms of brain development. the no-effect dose for developmental neurotoxicity in juvenile rats (5 mg/kg/day) was associated with plasma vigabatrin exposures (auc) less than 1/30 of those measured in pediatric patients receiving an oral dose of 50 mg/kg.

ic patients below the age of 1 month have not been established. the safety and effectiveness of vigabatrin as monotherapy for pediatric patients with infantile spasms (1 month to 2 years of age) have been established [see dosage and administration (2.3) and clinical studies (14.2)] . duration of therapy for infantile spasms was evaluated in a post hoc analysis of a canadian pediatric epilepsy network (cpen) study of developmental outcomes in infantile spasms patients. this analysis suggests that a total duration of 6 months of vigabatrin therapy is adequate for the treatment of infantile spasms. however, prescribers must use their clinical judgment as to the most appropriate duration of use [see clinical studies (14.2)] . abnormal mri signal changes and intramyelinic edema (ime) in infants and young children being treated with vigabatrin have been observed [see warnings and precautions ( 5.3 , 5.4 )] . juvenile animal toxicity data oral administration of vigabatrin (5, 15, or 50 mg/kg/day) to young rats during the neonatal and juvenile periods of development (postnatal days 4 to 65) produced neurobehavioral (convulsions, neuromotor impairment, learning deficits) and neurohistopathological (brain gray matter vacuolation, decreased myelination, and retinal dysplasia) abnormalities. the no-effect dose for developmental neurotoxicity in juvenile rats (the lowest dose tested) was associated with plasma vigabatrin exposures (auc) substantially less than those measured in pediatric patients at recommended doses. in dogs, oral administration of vigabatrin (30 mg/kg or 100 mg/kg/day) during selected periods of juvenile development (postnatal days 22 to 112) produced neurohistopathological abnormalities (brain gray matter vacuolation). neurobehavioral effects of vigabatrin were not assessed in the juvenile dog. a no-effect dose for neurohistopathology was not established in juvenile dogs; the lowest effect dose (30 mg/kg/day) was associated with plasma vigabatrin exposures lower than those measured in pediatric patients at recommended doses [see warnings and precautions (5.4) ] .

atrin were approximately 2-fold higher than the peak concentrations following the 3.0 g single oral dose. 12.3 pharmacokinetics vigabatrin displayed linear pharmacokinetics after administration of single doses ranging from 0.5 g to 4 g, and after administration of repeated doses of 0.5 g and 2.0 g twice daily. bioequivalence has been established between the oral solution and tablet formulations. the following pk information (t max , half-life, and clearance) of vigabatrin was obtained from stand-alone pk studies and population pk analyses. absorption following oral administration, vigabatrin is essentially completely absorbed. the time to maximum concentration (t max ) is approximately 1 hour for children and adolescents (3 years to 16 years of age) and adults, and approximately 2.5 hours for infants (5 months to 2 years of age). there was little accumulation with multiple dosing in adult and pediatric patients. a food effect study involving administration of vigabatrin to healthy volunteers under fasting and fed conditions indicated that the c max was decreased by 33%, t max was increased to 2 hours, and auc was unchanged under fed conditions. distribution vigabatrin does not bind to plasma proteins. vigabatrin is widely distributed throughout the body; mean steady-state volume of distribution is 1.1 l/kg (cv = 20%). metabolism and elimination vigabatrin is not significantly metabolized; it is eliminated primarily through renal excretion. the terminal half-life of vigabatrin is about 5.7 hours for infants (5 months to 2 years of age), 6.8 hours for children (3 to 9 years of age), 9.5 hours for children and adolescents (10 to 16 years of age), and 10.5 hours for adults. following administration of [14] c-vigabatrin to healthy male volunteers, about 95% of total radioactivity was recovered in the urine over 72 hours with the parent drug representing about 80% of this. vigabatrin induces cyp2c9, but does not induce other hepatic cytochrome p450 enzyme systems. specific populations geriatric the renal clearance of vigabatrin in healthy elderly patients (?65 years of age) was 36% less than those in healthy younger patients. this finding is confirmed by an analysis of data from a controlled clinical trial [see use in specific populations (8.5) ] . pediatric the clearance of vigabatrin is 2.4 l/hr for infants (5 months to 2 years of age), 5.1 l/hr for children (3 to 9 years of age), 5.8 l/hr for children and adolescents (10 years to 16 years of age) and 7 l/hr for adults. gender no gender differences were observed for the pharmacokinetic parameters of vigabatrin in patients. race no specific study was conducted to investigate the effects of race on vigabatrin pharmacokinetics. a cross study comparison between 23 caucasian and 7 japanese patients who received 1, 2, and 4 g of vigabatrin indicated that the auc, c max , and half-life were similar for the two populations. however, the mean renal clearance of caucasians (5.2 l/hr) was about 25% higher than the japanese (4.0 l/hr). inter-subject variability in renal clearance was 20% in caucasians and was 30% in japanese. renal impairment mean auc increased by 30% and the terminal half-life increased by 55% (8.1 hr vs 12.5 hr) in adult patients with mild renal impairment (clcr from >50 ml/min to 80 ml/min) in comparison to normal subjects. mean auc increased by two-fold and the terminal half-life increased by two-fold in adult patients with moderate renal impairment (clcr from >30 ml/min to 50 ml/min) in comparison to normal subjects. mean auc increased by 4.5-fold and the terminal half-life increased by 3.5-fold in adult patients with severe renal impairment (clcr from >10 to 30 ml/min) in comparison to normal subjects. adult patients with renal impairment dosage adjustment, including starting at a lower dose, is recommended for adult patients with any degree of renal impairment [see use in specific populations (8.6) and dosage and administration (2.4) ] . infants with renal impairment information about how to adjust the dose in infants with renal impairment is unavailable. pediatric patients 2 years and older with renal impairment although information is unavailable on the effects of renal impairment on vigabatrin clearance in pediatric patients 2 years and older, dosing can be calculated based upon adult data and an established formula [see use in specific populations (8.6) and dosage and administration (2.4) ] . hepatic impairment vigabatrin is not significantly metabolized. the pharmacokinetics of vigabatrin in patients with impaired liver function has not been studied. drug interactions phenytoin a 16% to 20% average reduction in total phenytoin plasma levels was reported in adult controlled clinical studies. in vitro drug metabolism studies indicate that decreased phenytoin concentrations upon addition of vigabatrin therapy are likely to be the result of induction of cytochrome p450 2c enzymes in some patients. although phenytoin dose adjustments are not routinely required, dose adjustment of phenytoin should be considered if clinically indicated [see drug interactions (7.1) ] . clonazepam in a study of 12 healthy adult volunteers, clonazepam (0.5 mg) coadministration had no effect on vigabatrin (1.5 g twice daily) concentrations. vigabatrin increases the mean c max of clonazepam by 30% and decreases the mean t max by 45% [see drug interactions (7.1) ] . other aeds when coadministered with vigabatrin, phenobarbital concentration (from phenobarbital or primidone) was reduced by an average of 8% to 16%, and sodium valproate plasma concentrations were reduced by an average of 8%. these reductions did not appear to be clinically relevant. based on population pharmacokinetics, carbamazepine, clorazepate, primidone, and sodium valproate appear to have no effect on plasma concentrations of vigabatrin [see drug interactions (7.1) ] . alcohol coadministration of ethanol (0.6 g/kg) with vigabatrin (1.5 g twice daily) indicated that neither drug influences the pharmacokinetics of the other. oral contraceptives in a double-blind, placebo-controlled study using a combination oral contraceptive containing 30 mcg ethinyl estradiol and 150 mcg levonorgestrel, vigabatrin (3 g/day) did not interfere significantly with the cytochrome p450 isoenzyme (cyp3a)-mediated metabolism of the contraceptive tested. based on this study, vigabatrin is unlikely to affect the efficacy of steroid oral contraceptives. additionally, no significant difference in pharmacokinetic parameters (elimination half-life, auc, c max , apparent oral clearance, time to peak, and apparent volume of distribution) of vigabatrin were found after treatment with ethinyl estradiol and levonorgestrel [see drug interactions (7.2) ] .

to 2 hours, and auc was unchanged under fed conditions. distribution vigabatrin does not bind to plasma proteins. vigabatrin is widely distributed throughout the body; mean steady-state volume of distribution is 1.1 l/kg (cv = 20%). metabolism and elimination vigabatrin is not significantly metabolized; it is eliminated primarily through renal excretion. the terminal half-life of vigabatrin is about 5.7 hours for infants (5 months to 2 years of age), 6.8 hours for children (3 to 9 years of age), 9.5 hours for children and adolescents (10 to 16 years of age), and 10.5 hours for adults. following administration of [14] c-vigabatrin to healthy male volunteers, about 95% of total radioactivity was recovered in the urine over 72 hours with the parent drug representing about 80% of this. vigabatrin induces cyp2c9, but does not induce other hepatic cytochrome p450 enzyme systems. specific populations geriatric the renal clearance of vigabatrin in healthy elderly patients (?65 years of age) was 36% less than those in healthy younger patients. this finding is confirmed by an analysis of data from a controlled clinical trial [see use in specific populations (8.5) ] . pediatric the clearance of vigabatrin is 2.4 l/hr for infants (5 months to 2 years of age), 5.1 l/hr for children (3 to 9 years of age), 5.8 l/hr for children and adolescents (10 years to 16 years of age) and 7 l/hr for adults. gender no gender differences were observed for the pharmacokinetic parameters of vigabatrin in patients. race no specific study was conducted to investigate the effects of race on vigabatrin pharmacokinetics. a cross study comparison between 23 caucasian and 7 japanese patients who received 1, 2, and 4 g of vigabatrin indicated that the auc, c max , and half-life were similar for the two populations. however, the mean renal clearance of caucasians (5.2 l/hr) was about 25% higher than the japanese (4.0 l/hr). inter-subject variability in renal clearance was 20% in caucasians and was 30% in japanese. renal impairment mean auc increased by 30% and the terminal half-life increased by 55% (8.1 hr vs 12.5 hr) in adult patients with mild renal impairment (clcr from >50 ml/min to 80 ml/min) in comparison to normal subjects. mean auc increased by two-fold and the terminal half-life increased by two-fold in adult patients with moderate renal impairment (clcr from >30 ml/min to 50 ml/min) in comparison to normal subjects. mean auc increased by 4.5-fold and the terminal half-life increased by 3.5-fold in adult patients with severe renal impairment (clcr from >10 to 30 ml/min) in comparison to normal subjects. adult patients with renal impairment dosage adjustment, including starting at a lower dose, is recommended for adult patients with any degree of renal impairment [see use in specific populations (8.6) and dosage and administration (2.4) ] . infants with renal impairment information about how to adjust the dose in infants with renal impairment is unavailable. pediatric patients 2 years and older with renal impairment although information is unavailable on the effects of renal impairment on vigabatrin clearance in pediatric patients 2 years and older, dosing can be calculated based upon adult data and an established formula [see use in specific populations (8.6) and dosage and administration (2.4) ] . hepatic impairment vigabatrin is not significantly metabolized. the pharmacokinetics of vigabatrin in patients with impaired liver function has not been studied. drug interactions phenytoin a 16% to 20% average reduction in total phenytoin plasma levels was reported in adult controlled clinical studies. in vitro drug metabolism studies indicate that decreased phenytoin concentrations upon addition of vigabatrin therapy are likely to be the result of induction of cytochrome p450 2c enzymes in some patients. although phenytoin dose adjustments are not routinely required, dose adjustment of phenytoin should be considered if clinically indicated [see drug interactions (7.1) ] . clonazepam in a study of 12 healthy adult volunteers, clonazepam (0.5 mg) coadministration had no effect on vigabatrin (1.5 g twice daily) concentrations. vigabatrin increases the mean c max of clonazepam by 30% and decreases the mean t max by 45% [see drug interactions (7.1) ] . other aeds when coadministered with vigabatrin, phenobarbital concentration (from phenobarbital or primidone) was reduced by an average of 8% to 16%, and sodium valproate plasma concentrations were reduced by an average of 8%. these reductions did not appear to be clinically relevant. based on population pharmacokinetics, carbamazepine, clorazepate, primidone, and sodium valproate appear to have no effect on plasma concentrations of vigabatrin [see drug interactions (7.1) ] . alcohol coadministration of ethanol (0.6 g/kg) with vigabatrin (1.5 g twice daily) indicated that neither drug influences the pharmacokinetics of the other. oral contraceptives in a double-blind, placebo-controlled study using a combination oral contraceptive containing 30 mcg ethinyl estradiol and 150 mcg levonorgestrel, vigabatrin (3 g/day) did not interfere significantly with the cytochrome p450 isoenzyme (cyp3a)-mediated metabolism of the contraceptive tested. based on this study, vigabatrin is unlikely to affect the efficacy of steroid oral contraceptives. additionally, no significant difference in pharmacokinetic parameters (elimination half-life, auc, c max , apparent oral clearance, time to peak, and apparent volume of distribution) of vigabatrin were found after treatment with ethinyl estradiol and levonorgestrel [see drug interactions (7.2) ] .

cy was the patient’s reduction in mean monthly frequency of complex partial seizures plus partial seizures secondarily generalized at end of study compared to baseline. study 1 study 1 (n=174) was a randomized, double-blind, placebo-controlled, dose-response study consisting of an 8-week baseline period followed by an 18-week treatment period. patients were randomized to receive placebo or 1, 3, or 6 g/day vigabatrin administered twice daily. during the first 6 weeks following randomization, the dose was titrated upward beginning with 1 g/day and increasing by 0.5 g/day on days 1 and 5 of each subsequent week in the 3 g/day and 6 g/day groups, until the assigned dose was reached. results for the primary measure of effectiveness, reduction in monthly frequency of complex partial seizures, are shown in table 8. the 3 g/day and 6 g/day dose groups were statistically significantly superior to placebo, but the 6 g/day dose was not superior to the 3 g/day dose. table 8. median monthly frequency of complex partial seizures + n baseline endstudy placebo 45 9.0 8.8 1 g/day vigabatrin 45 8.5 7.7 3 g/day vigabatrin 41 8.5 3.7 * 6 g/day vigabatrin 43 8.5 4.5 * * p<0.05 compared to placebo + including one patient with simple partial seizures with secondary generalization only figure 1 presents the percentage of patients (x-axis) with a percent reduction in seizure frequency (responder rate) from baseline to the maintenance phase at least as great as that represented on the y-axis. a positive value on the y-axis indicates an improvement from baseline (i.e., a decrease in complex partial seizure frequency), while a negative value indicates a worsening from baseline (i.e., an increase in complex partial seizure frequency). thus, in a display of this type, a curve for an effective treatment is shifted to the left of the curve for placebo. the proportion of patients achieving any particular level of reduction in complex partial seizure frequency was consistently higher for the vigabatrin 3 and 6 g/day groups compared to the placebo group. for example, 51% of patients randomized to vigabatrin 3 g/day and 53% of patients randomized to vigabatrin 6 g/day experienced a 50% or greater reduction in seizure frequency, compared to 9% of patients randomized to placebo. patients with an increase in seizure frequency >100% are represented on the y-axis as equal to or greater than -100%. figure 1. percent reduction from baseline in seizure frequency study 2 study 2 (n=183 randomized, 182 evaluated for efficacy) was a randomized, double-blind, placebo-controlled, parallel study consisting of an 8-week baseline period and a 16-week treatment period. during the first 4 weeks following randomization, the dose of vigabatrin was titrated upward beginning with 1 g/day and increased by 0.5 g/day on a weekly basis to the maintenance dose of 3 g/day. results for the primary measure of effectiveness, reduction in monthly complex partial seizure frequency, are shown in table 9. vigabatrin 3 g/day was statistically significantly superior to placebo in reducing seizure frequency. table 9. median monthly frequency of complex partial seizures n baseline endstudy placebo 90 9.0 7.5 3 g/day vigabatrin 92 8.3 5.5* *p<0.05 compared to placebo figure 2 presents the percentage of patients (x-axis) with a percent reduction in seizure frequency (responder rate) from baseline to the maintenance phase at least as great as that represented on the y-axis. a positive value on the y-axis indicates an improvement from baseline (i.e., a decrease in complex partial seizure frequency), while a negative value indicates a worsening from baseline (i.e., an increase in complex partial seizure frequency). thus, in a display of this type, a curve for an effective treatment is shifted to the left of the curve for placebo. the proportion of patients achieving any particular level of reduction in seizure frequency was consistently higher for the vigabatrin 3 g/day group compared to the placebo group. for example, 39% of patients randomized to vigabatrin (3 g/day) experienced a 50% or greater reduction in complex partial seizure frequency, compared to 21% of patients randomized to placebo. patients with an increase in seizure frequency >100% are represented on the y-axis as equal to or greater than -100%. figure 2. percent reduction from baseline in seizure frequency for both studies, there was no difference in the effectiveness of vigabatrin between male and female patients. analyses of age and race were not possible as nearly all patients were between the ages of 18 to 65 and caucasian. pediatric patients 3 to 16 years of age vigabatrin was studied in three double-blind, placebo-controlled, parallel-group studies in 269 patients who received vigabatrin and 104 patients who received placebo. no individual study was considered adequately powered to determine efficacy in pediatric patients age 3 years and above. the data from all three pediatric studies were pooled and used in a pharmacometric bridging analysis using weight-normalized doses to establish efficacy and determine appropriate dosing. all three studies were randomized, double-blind, placebo-controlled, parallel-group, adjunctive-treatment studies in patients aged 3 to 16 years with uncontrolled complex partial seizures with or without secondary generalization. the study period included a 6 to 10 week baseline phase and a 14 to 17 week treatment phase (composed of a titration and maintenance period). the pharmacometric bridging approach consisted of defining a weight-normalized dose-response, and showing that a similar dose-response relationship exists between pediatric patients and adult patients when vigabatrin was given as adjunctive therapy for complex partial seizures. dosing recommendations in pediatric patients 2 to 16 years of age were derived from simulations utilizing these pharmacometric dose-response analyses [see dosage and administration (2.2) ] . figure 1. percent reduction from baseline in seizure frequency figure 2. percent reduction from baseline in seizure frequency 14.2 infantile spasms the effectiveness of vigabatrin as monotherapy was established for infantile spasms in two multicenter controlled studies. both studies were similar in terms of disease characteristics and prior treatments of patients and all enrolled infants had a confirmed diagnosis of infantile spasms. study 1 study 1 (n=221) was a multicenter, randomized, low-dose high-dose, parallel-group, partially-blind (caregivers knew the actual dose but not whether their child was classified as low or high dose; eeg reader was blinded but investigators were not blinded) study to evaluate the safety and efficacy of vigabatrin in patients <2 years of age with new-onset infantile spasms. patients with both symptomatic and cryptogenic etiologies were studied. the study was comprised of two phases. the first phase was a 14 to 21 day partially-blind phase in which patients were randomized to receive either low-dose (18 to 36 mg/kg/day) or high-dose (100 to 148 mg/kg/day) vigabatrin. study drug was titrated over 7 days, followed by a constant dose for 7 days. if the patient became spasm-free on or before day 14, another 7 days of constant dose was administered. the primary efficacy endpoint of this study was the proportion of patients who were spasm-free for 7 consecutive days beginning within the first 14 days of vigabatrin therapy. patients considered spasm-free were defined as those patients who remained free of spasms (evaluated according to caregiver response to direct questioning regarding spasm frequency) and who had no indication of spasms or hypsarrhythmia during 8 hours of cctv eeg recording (including at least one sleep-wake-sleep cycle) performed within 3 days of the seventh day of spasm freedom and interpreted by a blinded eeg reader. seventeen patients in the high-dose group achieved spasm freedom compared with 8 patients in the low dose group. this difference was statistically significant (p=0.0375). primary efficacy results are shown in table 10. table 10. spasm freedom by primary criteria (study 1) vigabatrin treatment group 18 to 36 mg/kg/day 100 to 148 mg/kg/day [n=114] [n=107] n (%) n (%) patients who achieved spasm freedom 8 (7.0) 17 (15.9) p=0.0375 note: primary criteria were evaluated based on caregiver assessment plus cctv eeg confirmation within 3 days of the seventh day of spasm freedom. study 2 study 2 (n=40) was a multicenter, randomized, double-blind, placebo-controlled, parallel-group study consisting of a pre-treatment (baseline) period of 2 to 3 days, followed by a 5-day double-blind treatment phase during which patients were treated with vigabatrin (initial dose of 50 mg/kg/day with titration allowed to 150 mg/kg/day) or placebo. the primary efficacy endpoint in this study was the average percent change in daily spasm frequency, assessed during a pre-defined and consistent 2-hour window of evaluation, comparing baseline to the final 2 days of the 5-day double-blind treatment phase. no statistically significant differences were observed in the average frequency of spasms using the 2-hour evaluation window. however, a post-hoc alternative efficacy analysis, using a 24-hour clinical evaluation window found a statistically significant difference in the overall percentage of reductions in spasms between the vigabatrin group (68.9%) and the placebo group (17.0%) (p=0.030). duration of therapy for infantile spasms was evaluated in a post hoc analysis of a canadian pediatric epilepsy network (cpen) study of developmental outcomes in infantile spasms patients. the 38/68 infants in the study who had responded to vigabatrin therapy (complete cessation of spasms and hypsarrhythmia) continued vigabatrin therapy for a total duration of 6 months therapy. the 38 infants who responded were then followed for an additional 18 months after discontinuation of vigabatrin to determine their clinical outcome. a post-hoc analysis indicated no observed recurrence of infantile spasms in any of these 38 infants.

nt may continue without recommended testing according to clinical judgment with appropriate patient or caregiver counseling. patients or caregivers should be informed that if baseline or subsequent vision is not normal, vigabatrin for oral solution should only be used if the benefits of vigabatrin for oral solution treatment clearly outweigh the risks of additional vision loss. advise patients and caregivers that vision testing may be insensitive and may not detect vision loss before it is severe. also advise patients and caregivers that if vision loss is documented, such loss is irreversible. ensure that both of these points are understood by patients and caregivers. patients and caregivers should be informed that if changes in vision are suspected, they should notify their physician immediately. vigabatrin rems program vigabatrin for oral solution is available only through a restricted program called the vigabatrin rems program [see warnings and precautions (5.2) ] . inform patients/caregivers of the following: patients/caregivers must be enrolled in the program. vigabatrin is only available through pharmacies that are enrolled in the vigabatrin rems program. mri abnormalities in infants inform caregiver(s) of the possibility that infants may develop an abnormal mri signal of unknown clinical significance [see warnings and precautions (5.3) ] . suicidal thinking and behavior counsel patients, their caregiver(s), and families that aeds, including vigabatrin, may increase the risk of suicidal thoughts and behavior. also advise patients and caregivers of the need to be alert for the emergence or worsening of symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts of self-harm. behaviors of concern should be reported immediately to healthcare providers [see warnings and precautions (5.5) ] . pregnancy advise pregnant women and women of child-bearing potential that the use of vigabatrin during pregnancy can cause fetal harm which may occur early in pregnancy before many women know they are pregnant. instruct patients to notify their physician if they become pregnant or intend to become pregnant during therapy. advise patients that there is a pregnancy exposure registry that collects information about the safety of antiepileptic drugs during pregnancy [see use in specific populations (8.1) ] . nursing counsel patients that vigabatrin is excreted in breast milk. because of the potential for serious adverse reactions in nursing infants from vigabatrin, breastfeeding is not recommended. if a decision is made to breastfeed, nursing mothers should be counseled to observe their infants for signs of vision loss, sedation and poor sucking [see use in specific populations (8.2) ] . withdrawal of vigabatrin therapy instruct patients and caregivers not to suddenly discontinue vigabatrin therapy without consulting with their healthcare provider. as with all aeds, withdrawal should normally be gradual [see warnings and precautions (5.6) ] . manufactured in india by: watson pharma private limited verna, salcette goa 403 722 india manufactured for: teva pharmaceuticals usa, inc. north wales, pa 19454 rev. f 2/2022