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VIGABATRIN MSN is a brand name for Vigabatrin. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: Treatment in combination with other antiepileptic medicinal products for patients with resistant partial epilepsy with or without secondary generalisation, that is where all other appropriate medicinal product combinations have proved inadequate or have not been tolerated. Monotherapy in the treatment of infantile…
Verbatim from this product's MHRA label. Tap a section to expand.
Vigabatrin MSN treatment may only be initiated by a specialist in epileptology, neurology or paediatric neurology. Follow-up should be arranged under supervision of a specialist in epileptology, neurology or paediatric neurology. Posology Vigabatrin MSN is for oral administration once or twice daily and may be taken before or after meals.
g. water, fruit juice or milk) immediately before oral administration. If the control of epilepsy is not clinically significantly improved after an adequate trial, vigabatrin treatment should be discontinued. Vigabatrin should then be gradually withdrawn under close medical supervision.
A clinically meaningful improvement is usually observed within 2 to 4 weeks in patients with infantile spasms, and within 12 weeks in patients with refractory complex partial seizures. Adults Maximal efficacy is usually seen in the 2-3 g/day range.
A starting dose of 1 g daily should be added to the patient's current antiepileptic medicinal product regimen. 5 g increments at weekly intervals depending on clinical response and tolerability. The highest recommended dose is 3 g/day.
No direct correlation exists between the plasma concentration and the efficacy. 2). Paediatric population Resistant partial epilepsy The recommended starting dose in neonates, children and adolescents is 40 mg/kg/day. 5-3 g/day >50 kg: 2-3 g/day The maximum recommended dose in each of these categories should not be exceeded.
Monotherapy for infantile spasms (West's Syndrome) The recommended starting dose is 50 mg/kg/day. This may be titrated over a period of one week if necessary. Doses of up to 150 mg/kg/day have been used with good tolerability. Older people and patients with renal impairment Since vigabatrin is eliminated via the kidney, caution should be exercised when administering the drug to the older people and more particularly in patients with creatinine clearance less than 60 ml/min.
Adjustment of dose or frequency of administration should be considered. Such patients may respond to a lower maintenance dose. 8).
Summary of the safety profile Visual field defects ranging from mild to severe have been reported frequently in patients receiving vigabatrin. Severe cases are potentially disabling. The onset is usually after months to years of vigabatrin therapy.
4). Approximately 50% of patients in controlled clinical studies have experienced undesirable effects during vigabatrin treatment. In adults, these were mostly central nervous system related such as sedation, drowsiness, fatigue and impaired concentration.
However, in children excitation or agitation is frequent. The incidence of these undesirable effects is generally higher at the beginning of treatment and decreases with time. As with other antiepileptic drugs, some patients may experience an increase in seizure frequency, including status epilepticus with vigabatrin.
Patients with myoclonic seizures may be particularly liable to this effect. New onset myoclonus and exacerbation of existing myoclonus may occur in rare cases. Tabulated list of adverse reactions Undesirable effects ranked under headings of frequency are listed below, using the following convention: Very common (≥ 1/10); common (≥ 1/100 to <1/10); uncommon (≥ 1/1,000 to <1/100); rare (≥ 1/10,000 to <1/1,000); very rare (<1/10,000); not known (cannot be estimated from the available data).
4). Eye disorders visual field defect vision blurred, diplopia, retinal disorder (mainly optic atrophy Reduced visual acuity nystagmus peripheral) Gastrointe stinal disorders nausea, vomiting, abdominal pain Hepato- biliary disorders hepatitis Skin and subcutane ous tissue disorders alopecia rash angioedema, urticaria Musculosk eletal and connective tissue disorders arthralgia General disorders and administrat ion site conditions fatigue oedema, irritability Investigatio ns*** weight increased *Psychiatric reactions have been reported during vigabatrin therapy.
Except for the treatment of infantile spasms, Vigabatrin MSN should not be initiated as monotherapy. Visual field defects (VFD) have been reported in patients receiving vigabatrin with a high prevalence (about 1/3 of patients). 1. The onset is usually after months to years of vigabatrin therapy.
The degree of visual field restriction may be severe. Most of the patients with perimetry-confirmed defects have been asymptomatic. Hence, this undesirable effect can only be reliably detected by systematic perimetry which is usually possible only in patients with a developmental age of more than 9 years.
For infants, children and those not able to perform perimetry, electroretinography (ERG), optical coherence tomography (OCT) and/or other methods appropriate for the patient can be considered. Patients should undergo systematic screening examination when starting vigabatrin and at regular intervals for detection of visual field defects and reduced visual acuity (see Visual Field Defects and Visual Acuity).
Vision assessment is recommended at baseline (no later than 4 weeks after starting vigabatrin), every 3 to 6 months during therapy, and about 3 to 6 months after the discontinuation of therapy. Available data suggests that visual field defects are irreversible even after discontinuation of vigabatrin.
A deterioration of VFD after the treatment is discontinued cannot be excluded. Therefore, vigabatrin should only be used after a careful assessment of the balance of benefits and risk compared with alternatives. Because of the risk of visual loss, a gradual withdrawal should start immediately if no meaningful improvement is observed following an adequate treatment attempt.
Patient response to and continued need for vigabatrin should be periodically reassessed. Vigabatrin is not recommended for use in patients with any pre-existing clinically significant visual field defect. Visual Field Defects (VFD) Based on available data, the usual pattern is a concentric constriction of the visual field of both eyes, which is generally more marked nasally than temporally.
1.
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4). Depression was a common psychiatric reaction in clinical trials but seldom required discontinuation of vigabatrin. **Rare reports of encephalopathic symptoms such as marked sedation, stupor and confusion in association with non- specific slow wave activity on electroencephalogram have been described soon after the initiation of vigabatrin treatment.
4). ***Laboratory data indicate that vigabatrin treatment does not lead to renal toxicity. Decreases in ALT and AST, which are considered to be a result of inhibition of these aminotransferases by vigabatrin, have been observed. Chronic treatment with vigabatrin may be associated with a slight decrease in haemoglobin which rarely attains clinical significance.
Paediatric population Psychiatric disorders Very common: excitation, agitation Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product.
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In the central visual field (within 30 degree of eccentricity), frequently an annular nasal defect is seen. However, the VFDs reported in patients receiving vigabatrin have ranged from mild to severe. Severe cases may be characterized by tunnel vision.
Blindness was also reported in severe cases. Most patients with perimetry-confirmed defects had not previously spontaneously noticed any symptoms, even in cases where a severe defect was observed in perimetry. Available evidence suggests that the VFD is irreversible even after discontinuation of vigabatrin.
A deterioration of VFD after the treatment is discontinued cannot be excluded. Pooled data from prevalence surveys suggest that as many as 1/3 of patients receiving vigabatrin therapy have VFDs. Males may be at greater risk than females.
1. A possible association between the risk of visual field defects and the extent of vigabatrin exposure, both in terms of daily dose (from 1 gram to more than 3 grams) and in terms of duration of treatment (maximum during the first three years) has been shown in this study.
All patients should have ophthalmological consultation with visual field examination before the initiation of vigabatrin treatment. 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.
Because vision testing in infants is difficult, vision loss may not be detected until it is severe. For patients receiving vigabatrin, visual field and/or retinal assessment is recommended at baseline (no later than 4 weeks after starting vigabatrin), every 3 to 6 months while on therapy, and about 3-6 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. , 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 patient and/or caregiver must be given a thorough description of the frequency and implications of the development of VFD during vigabatrin treatment.
Patients should be instructed to report any new visual problems and symptoms which may be associated with visual field constriction. If visual symptoms develop, the patient should be referred to an ophthalmologist. If a visual field constriction is observed during follow-up, consideration should be given to gradual discontinuation of vigabatrin.
If the decision to continue treatment is made, consideration should be given to more frequent follow-up (perimetry) in order to detect progression or sight threatening defects. Vigabatrin should not be used concomitantly with other retinotoxic drugs.
Visual acuity The prevalence of reduced visual acuity in vigabatrin treated patients is unknown. 8). Visual acuity should be assessed during ophthalmological consultations, before initiation of vigabatrin treatment and […]