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SABRIL (vigabatrin oral solution) causes permanent damage to vision in a high percentage of patients [see BOXED WARNING: Vision Loss and WARNINGS AND PRECAUTIONS, Vision Loss].

Adverse Reactions in Clinical Trials

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.

Adverse Reactions in U.S. and Primary Non-U.S. Clinical Studies

In U.S. and primary non-U.S. clinical studies of 4,079 SABRIL (vigabatrin oral solution) treated patients, the most commonly observed ( ≥ 5%) adverse reactions associated with the use of SABRIL (vigabatrin oral solution) in combination with other AEDs were headache (18%), somnolence (17%), fatigue (16%), dizziness (15%), convulsion (11%), nasopharyngitis (10%), weight increased (10%), upper respiratory tract infection (10%), visual field defect (9%), depression (8%), tremor (7%), nystagmus (7%), nausea (7%), diarrhea (7%), memory impairment (7%), insomnia (7%), irritability (7%), coordination abnormal (7%), vision blurred (6%), diplopia (6%), vomiting (6%), influenza (6%), pyrexia (6%), and rash (6%).

The adverse reactions most commonly associated with SABRIL (vigabatrin oral solution) treatment discontinuation in ≥ 1% of patients were convulsion (1.4%) and depression (1.5%).

Most Common Adverse Reactions in Controlled Clinical Trials

Refractory Complex Partial Seizures in Adults

Table 2 lists the treatment emergent adverse reactions that occurred in ≥ 2% and more than one patient per SABRIL (vigabatrin oral solution) -treated group and that occurred more frequently than in placebo patients from 2 U.S. add-on clinical studies of refractory CPS in adults.

Table 2. Treatment Emergent Adverse Reactions Occurring in ≥ 2% and More than One Patient per SABRIL (vigabatrin oral solution) -Treated Group and More Frequently than in Placebo Patients (Studies 024 and 025)

Post Marketing Experience

The following serious adverse events have been reported since approval and use of SABRIL (vigabatrin oral solution) worldwide. All serious adverse events that are not listed above as adverse events reported in clinical trials, that are not relatively common in the population and are not too vague to be useful are listed in this section. These reactions are reported voluntarily from a population of uncertain size; therefore, it is not possible to estimate their frequency or establish a causal relationship to drug exposure. Events 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: Deafness

Endocrine: Delayed puberty

Gastrointestinal: Gastrointestinal hemorrhage, esophagitis

General: Developmental delay, facial edema, malignant hyperthermia, multi-organ failure

Hepatobiliary: Cholestasis

Nervous System: Dystonia, encephalopathy, hypertonia, hypotonia, muscle spasticity, myoclonus, optic neuritis

Psychiatric: Acute psychosis, apathy, delirium, hypomania, neonatal agitation, psychotic disorder

Respiratory: Laryngeal edema, pulmonary embolism, respiratory failure, stridor

Skin and Subcutaneous Tissue: Angioedema, maculo-papular rash, pruritus

For detailed information about Drug Interactions see CLINICAL PHARMACOLOGY, Pharmacokinetics, Drug Interactions..

Phenytoin

A 16% to 20% average reduction in total phenytoin plasma levels was reported in controlled clinical studies.

Other AEDs

There are no clinically significant pharmacokinetic interactions between SABRIL (vigabatrin oral solution) 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.

Clonazepam

In a study of 12 healthy volunteers, clonazepam (0.5 mg) co-administration had no effect on SABRIL (vigabatrin oral solution) (1.5 g twice daily) concentrations. SABRIL (vigabatrin oral solution) increases the mean Cmax of clonazepam by 30% and decreases the mean tmax by 45%.

Oral Contraceptives

SABRIL (vigabatrin oral solution) is unlikely to affect the efficacy of steroid oral contraceptives.

Drug-Laboratory Test Interactions

SABRIL (vigabatrin oral solution) 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 SABRIL (vigabatrin oral solution) may preclude the use of these markers, especially ALT, to detect early hepatic injury.

SABRIL (vigabatrin oral solution) 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).

Drug Abuse And Dependence

Controlled Substance Class

Vigabatrin is not a controlled substance.

Abuse

Vigabatrin did not produce adverse events or overt behaviors associated with abuse when administered to humans or animals. It is not possible to predict the extent to which a CNS active drug will be misused, diverted, and/or abused once marketed. Consequently, physicians should carefully evaluate patients for history of drug abuse and follow such patients closely, observing them for signs of misuse or abuse of vigabatrin (e.g., incrementation of dose, drug-seeking behavior).

Dependence

Following chronic administration of vigabatrin to animals, there were no apparent withdrawal signs upon drug discontinuation. However, as with all AEDs, vigabatrin should be withdrawn gradually to minimize increased seizure frequency [see WARNINGS AND PRECAUTIONS, Withdrawal of Antiepileptic Drugs (AEDs) and PATIENT INFORMATION].

Last reviewed on RxList: 3/7/2011
This monograph has been modified to include the generic and brand name in many instances.