Treatment of baclofen overdose by haemodialysis: a pharmacokinetic study

1Department of Internal Medicine, Far Eastern Memorial Hospital, 2Department of Internal Medicine and 3Department of Emergency Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan Baclofen is currently used in the treatment of muscle spasticity, especially in patients with multiple sclerosis or in patients with spinal or cerebral disorders. Baclofen is eliminated predominantly by the kidneys [1], putting patients with impaired renal function at particular risk for baclofen accumulation. Several investigators have suggested that haemodialyis is effective in the removal of baclofen [2], however the pharmakokinetics of baclofen elimination during haemodialysis remains unclear. We herein report a baclofen-associated encephalopathy, which was resolved by haemodialysis, and pharmacokinetic data is presented. To our knowledge, this is the first reported case of baclofen-related encephalopathy with pharmacokinetic data during haemodialysis treatment. A 70-year-old woman with end-stage renal disease (ESRD) was treated by haemodialysis regularly for 14 years. She was anuric and received adequate haemodialysis at Kt/V 1.95. She presented with left leg soreness and was given 5 mg of oral baclofen three times daily from the local clinic, receiving a cumulative dose of 45 mg in 3 days. The patient became disoriented, in a state of confusion and was referred to our hospital for evaluation. At admission, she was found drowsy, her blood pressure was 199/60 mmHg and temperature 36.7°C. Laboratory data showed haemoglobin 8.1 g/dl, WBC 4900/mm3, with a normal differential count and platelets 268 000/mm3. Serum sodium was 147.4 mmol/l, potassium 4.42 mmol/l, ammonia <1 µmol/l, sugar 107 mg/dl, urea 51 mmol/l and creatinine 8.26 mg/dl. The transaminases were normal. A brain CT scan showed cortical atrophy and leukoaraiosis. Under the diagnosis of baclofen intoxication, she received emergency haemodialysis. The dialyser had ethylene vinyl alcohol copolymer resin filters with a surface area of 2.0 m2, and the blood flow rate was at a constant 300 ml/h for 4 h without ultrafiltration. There was a complete recovery of consciousness 8 h later. She received another haemodialysis session 30 h after admission. The patient was discharged from the hospital 72 h later in good condition.