Mind Matters: Muscle Relaxants and Kidney Health, a Case of Baclofen Neurotoxicity

Introduction: Drug adjustment in the setting of chronic kidney disease is something as physicians we stay vigilant. When prescribing muscle relaxants, the rule does not change. Although baclofen neurotoxicity in presence of CKD is rare, a few reported cases have been evaluated and we present one below. Case Description: 75-year-old female with hypertension, Type 2 diabetes, hyperlipidemia, and CKD stage IV presented with altered mental status from an assisted living facility. Two days prior, the patient had been prescribed baclofen 10mg tid and was taking it as directed. CT scan of the head revealed no acute intracranial issues. Nephrology was consulted due to elevated creatinine (3.0) and BUN (49), with positive protein in urine analysis. Metabolic encephalopathy was deemed less likely due to uremia given renal parameters, while baclofen neurotoxicity was considered more probable given underlying kidney disease and recent baclofen use in the setting of low GFR. Hemodialysis was initiated due to progressing encephalopathy, leading to improved alertness following the first session. Discussion: Approximately 10 to 15% of baclofen undergoes hepatic metabolism, while the remaining 85 to 90% is excreted by the kidneys. Baclofen penetrates CNS by directly crossing the blood brain barrier. Baclofen elimination is heavily dependent on renal clearance and patients with reduced kidney function are at higher risk for intoxication. While studies have examined the relationship between dosage and encephalopathy development with the use of baclofen, further data are required to comprehensively assess the safety profile and prescribing guidelines for this medication in CKD patients. This case emphasizes the ongoing quest to refine dose adjustments based on GFR and will serve as a gateway to explore the broader effects of baclofen in CKD. Nevertheless, it's imperative for clinicians to exercise caution, recognizing that even muscle relaxants such as baclofen can pose risks in individuals with compromised renal function.