Topic Discussion: Baclofen Neurotoxicity in patients with impaired renal function

  Baclofen is an oral derivative of gamma-aminobutyric acid (GABA) used to treat muscular spasticity from disorders of the central nervous system. It is also used in medical ICU and neurological ICU for alcohol withdrawal, myclonus and other reasons. It is contra indicated in patients with abnormal renal function. Recently, there have been many cases described of this entity where dialysis ultimately was needed to restore normal neuro function of the patient.  Baclofen toxicity presents as altered mental status, somnolence, respiratory depression and even seizures and coma.  

Patients especially on dialysis, the half life of the drug is significantly increased and recommended dose or even low doses of baclofen as little as 5mg or cumulative dose of 15mg can cause rapid accumulation and severe toxicity. 
One of the first cases were reported in 2000 in NDT. Roberts et al describe three cases where aggressive dialysis made full recovery in patients who were ESRD. Although mechanism of baclofen elimination during HD is not well understood but up to 79% of the serum baclofen can be eliminated by one HD session.

The largest study that looked at all literature review was of 41 patients.  Most were elderly males, and 62% on dialysis. The manifestations of the drug toxicity happened 2-3 days later. The recovery time was 2 hours in patients who received HD to 8 days with conservative management.