Vigabatrin dosing during haemodialysis

The antiepileptic drug vigabatrin has shown efficacy in the treatment of patients with refractory epilepsy. Unlike many other antiepileptics it is not bound to plasma protein and mainly eliminated by the kidney. Although the therapeutic and toxic serum concentration range is not clearly defined and efficacy and toxicity are not closely correlated with the dose, factors decreasing vigabatrin elimination such as advanced age or renal failure may pose risk of untoward effects. Thus far there are no dose recommendations available for patients on haemodialysis. We report on an epileptic patient who experienced severe, partially reversible renal failure as a consequence of near-drowning. In this patient serum concentrations of vigabatrin were measured repeatedly both during haemodialysis and after partial recovery of renal function. The terminal elimination half-life in this patient was 41 hours during the period of severe renal failure (creatinine clearance < 5 ml/min). As about 60% of vigabatrin was removed from the blood pool by haemodialysis in these patients the antiepileptic should be administered after dialysis. To maintain serum concentrations in the usual range and to control seizure activity only 500 mg vigabatrin every 3 days were necessary.