SABRIL

What it is

Sabril contains vigabatrin 500 mg per tablet or oral powder sachet. Tablets are white to off-white, oval biconvex, film-coated tablets with a break-mark on one side and "SABRIL" or "SABRILEX" engraved on the other side. Oral powder is supplied as white to off-white granular powder.

Approved indications

— Treatment of epilepsy which is not satisfactorily controlled by other antiepileptic drugs.

Dosing overview

Vigabatrin is intended for oral administration once or twice daily. Initiation of treatment should be as add-on therapy in epilepsy which is not satisfactorily controlled by other drugs, with a starting daily dose of 2 g (4 tablets) added on to the patient's current antiepileptic drug regimen. If necessary the daily dose may be increased or decreased in 0.5 g or 1.0 g increments at weekly or greater intervals depending on clinical response and tolerability. Increasing the dose beyond 4 g/day does not usually result in greater efficacy. For children, the starting dose is 1 g daily for those aged 3–9 years and 2 g daily for those aged 10 years and older. When administering the sachet, the contents should be dissolved in water or a soft drink immediately prior to oral administration.

Key safety warnings

Visual field defects have been reported in patients receiving vigabatrin, possibly resulting from increased levels of GABA in the retina, with males at greater risk than females. Asymptomatic visual field defects appear to be frequent (about 30 percent) whereas symptomatic visual field constriction of various degrees is uncommon. In most reported cases, visual field defects persisted even after discontinuation of treatment, and available evidence suggests that they are irreversible. Appropriate visual field testing should be performed at baseline and during routine follow-up of the patient (initially and at about six month intervals), with static perimetry (such as Humphrey or Octopus) being the preferred method for detecting vigabatrin-associated visual field defects. Antiepileptic drugs, including vigabatrin, increase the risk of suicidal thoughts or behaviour in patients taking these drugs for any indication. Patients treated with any antiepileptic drug for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behaviour, and any unusual changes in mood or behaviour. Drowsiness has been observed in clinical trials and patients should be warned of this possibility at the start of treatment. Vigabatrin should be used with caution in patients with a history of psychosis, depression or behavioural problems, as psychiatric events including agitation, depression, abnormal thinking and paranoid reactions have been reported during vigabatrin therapy, though these were usually reversible when vigabatrin doses were reduced or gradually discontinued.

Contraindications

Sabril is contraindicated for patients who have a history of hypersensitivity to vigabatrin or any of the components.

PBS listing

The 500 mg tablet is listed on the PBS as 2 items with streamlined restriction at an ex-manufacturer price of A$68.60. The 500 mg oral powder sachet is also listed as 2 PBS items with streamlined restriction at an ex-manufacturer price of A$44.41.

Regulatory history

Sabril vigabatrin oral powder sachet (0.5 g) was first listed on the ARTG on 17 July 1995, and the 500 mg tablet formulation was first listed on 12 May 2008.