Antiepileptic
Antiepileptic
Indications And Clinical Uses: For the adjunctive management of epilepsy which is not satisfactorily controlled by conventional therapy.
Precautions: Patients with a History of Psychosis: Behavioral disturbances such as aggression and psychotic episodes have been reported following initiation of vigabatrin therapy. A history of abnormal behavior or psychosis appears to be a predisposing factor for such reactions, therefore treatment in such patients should be initiated cautiously at low doses and with frequent monitoring.
Geriatrics and Patients with Renal Impairment: Vigabatrin is eliminated via the kidney and caution should be exercised when administering the drug to elderly patients and to patients with renal impairment.
Patients with Myoclonic Seizures: As with other antiepileptic drugs, some patients may experience an increase in seizure frequency with vigabatrin. Patients with myoclonic seizures may be particularly liable to this effect.
Discontinuation of Therapy: As with other antiepileptic drugs, abrupt discontinuation may lead to rebound seizures. If a patient is to be withdrawn from vigabatrin treatment, it is recommended that this be done gradually by reducing the dose over a 2- to 4-week period if possible.
Drug Interactions: During concurrent vigabatrin administration, mean decreases of 16 to 33% in phenytoin levels have been reported. A 9 to 21% reduction in phenobarbital levels has also been seen in patients receiving concomitant vigabatrin treatment. The clinical relevance of these decreases is not known.
Occupational Hazards: Patients with uncontrolled epilepsy should not drive or handle potentially dangerous machinery. During clinical trials, the most common adverse reactions observed were drowsiness and fatigue. Patients should be advised to refrain from activities requiring mental alertness or physical coordination until they are sure that vigabatrin does not affect them adversely.
Adverse Reactions: Vigabatrin is generally well tolerated in epileptic patients. Adverse events are mainly CNS-related and probably a secondary consequence of increased GABA levels caused by vigabatrin.
Most Frequent Adverse Events (incidence higher than placebo): fatigue, headache, drowsiness, dizziness, depression, weight increase, agitation, tremor, abnormal vision, amnesia.
Symptoms And Treatment Of Overdose: Symptoms and Treatment: There is no specific antidote. The usual supportive measures should be employed. Measures to remove unabsorbed drug should be considered. Activated charcoal has been shown to not significantly adsorb vigabatrin in an in vitro study. 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%
Dosage And Administration: Vigabatrin is intended for oral administration once or twice daily and may be taken with or without food. Vigabatrin should be added to the patient’s current antiepileptic therapy.
Adults: The recommended starting dose is 1 g/day, although patients with severe seizure manifestations may require a starting dose of up to 2 g/day. The daily dose may be increased or decreased in increments of 0.5 g depending on clinical response and tolerability. The optimal dose range is between 2 to 4 g/day. Increasing the dose beyond 4 g/day does not usually result in improved efficacy and may increase the occurrence of adverse reactions.
Availability And Storage: Sachets: Each sachet of white to off-white granular powder contains: vigabatrin 0.5 g. Lactose-free. Cartons of 50.
Tablets: Each white to off-white, film-coated, oval, biconvex tablet, imprinted ‘SABRIL’ on one side, contains: vigabatrin 500 mg. Nonmedicinal ingredients: cellulose, hydroxypropyl methylcellulose, magnesium stearate, polyethylene glycol, povidone, sodium starch glycolate and titanium dioxide. Lactose-free. HDPE bottles of 100.
