Baclofen toxicity in patients with advanced nephropathy: proposal for new labeling

Despite several reports in the literature of baclofen toxicity in patients with renal dysfunction, the drug is being used for many patients.

Herein we report a case of baclofen-induced encephalopathy in a patient with pre-end-stage renal disease and review the literature regarding the magnitude of baclofen toxicity in patients with renal insufficiency. A Medline search for studies in English was performed. Twenty-one case reports involving 41 patients (including our patient) were identified.

The majority of patients were elderly (62.5% above 60 years) males (56.3%) on dialysis (62.9%). Neurotoxicities were almost always present at presentation. Manifestations of baclofen toxicity usually started 2-3 days after starting baclofen; however, periods as long as 16 weeks have been reported. The daily dose of baclofen ranged from 5 to 60 mg with a mean dose of 20 mg. Hemodialysis (HD) was the most common treatment modality used for drug elimination (65.7%). The recovery time ranged from 2 h in patients who received HD, to 8 days with conservative treatment.

The literature does not mention a clear recommendation about baclofen safety and dose adjustment, or a minimum level of kidney function below which the drug should not be used.