Background: Baclofen is a centrally acting gamma-aminobutyric acid agonist used for spasticity of spinal origin and mainly excreted unchanged by the kidneys. We report haemodialysis clearance and the haemodialysis removal rate constant of baclofen in a comatose patient with baclofen overdose due to acute renal failure.
Case report: A 60-year-old man with spastic tetraplegia on chronic baclofen therapy was admitted due to pneumonia and acute renal failure. The patient became comatose and, as a result of the baclofen dosage being left unchanged despite a deterioration leading to renal failure due to hypotension, the concentration of baclofen was determined to be in the toxic range (0.70 mg/L). During a 4-hour-long bicarbonate haemodialysis the patient woke up and became completely orientated and cooperative. Baclofen therapy was subsequently stopped, and the patient remained conscious. The pharmacokinetics calculations revealed a baclofen haemodialysis removal rate constant of 0.152 h(-1) and a haemodialysis clearance of 2.14 mL/s.
Conclusions: Patients on a stable baclofen regime can develop baclofen toxicity due to acute renal failure. Haemodialysis removes baclofen as effectively as normal kidneys, and it would appear that haemodialysis is a reasonable treatment modality in patients with accidental baclofen overdose due to acute renal failure.