Chronic Kidney Disease and Baclofen

Baclofen is a medication often used to treat muscle spasticity, such as from a spinal cord injury or multiple sclerosis. It may also be used for intractable hiccups and muscle spasms near the end of life, and off-label to treat alcohol abuse or opioid withdrawal symptoms. Baclofen is also used in the treatment of sleep-related painful erections.

Chemically, baclofen is a derivative of the neurotransmitter GABA (γ-aminobutyric acid). It is believed to work by activating (or agonizing) GABA receptors, specifically the GABAB receptors.

It can be administered orally or (in severe cases) by intrathecal pump (delivered directly into the spinal canal via an implantable pump device). It is sometimes used transdermally (applied topically to the skin).

Adverse effects of baclofen include drowsiness, dizziness, weakness, fatigue, headache, trouble sleeping, nausea and vomiting, poor concentration and recall (resembling dementia), urinary retention, or constipation.

Around 70 to 85 percent of baclofen gets excreted unchanged in the urine. Which means that the duration of its action gets prolonged in patients with kidney problems. Reports have suggested that patients with Chronic Kidney Disease may be especially at risk for the adverse effects[1]. Older patients appear to be even more sensitive to baclofen's adverse effects[2].

As baclofen does not readily cross the blood-brain barrier, patients may require a high dose to treat their spasticity effectively. As a result of this, most of the patients also develop neurotoxicity with encephalopathy (a change in how your brain functions)[3].

It will not come as a great surprise, but in the US, baclofen has been used as a recreational drug by adolescents. Also, from 2014 to 2017 baclofen misuse, toxicity and use in suicide attempts among adults in the US have significantly increased[4].

[1] Wolf et al: Baclofen Toxicity in Kidney Disease in American Journal of Kidney Diseases – 2018
[2] Chauvin et al: Baclofen has a risk of encephalopathy in older adults receiving dialysis in Kidney International - 2002
[3] Muanda et al: Association of Baclofen With Encephalopathy in Patients With Chronic Kidney Disease in JAMA – 2019
[4] Reynolds et al: Trends in gabapentin and baclofen exposures reported to U.S. poison centers in Clinical Toxicology - 2020