Exploring the Link Between Intravenous Methocarbamol and Acute Kidney Injury

Abstract

Background: Methocarbamol is a central nervous system depressant with antispasmodic properties used as a skeletal muscle relaxant as part of a multimodal analgesia regimen in critically ill patients. Intravenous (IV) methocarbamol contains polyethylene glycol (PEG) 300 and propylene glycol (PG) which have been associated with acute kidney injury (AKI). To mitigate AKI risk, IV methocarbamol is limited to 72 consecutive hours, followed by a 48-hour drug-free interval (DFI). Objective: To characterize the incidence of AKI in intensive care unit (ICU) patients receiving IV methocarbamol. Methods: This is a single-center, retrospective evaluation of adult trauma or surgical ICU patients who received at least 3 consecutive doses of IV methocarbamol. The primary outcome was the difference in SCr from day 1 through day 7 after IV methocarbamol initiation. Results: A total of 68 patients met inclusion criteria. Four patients were classified in the non-DFI group. There was no difference in the median (IQR) SCr (mg/dL) measured at any time point from day 1 through day 7 after IV methocarbamol initiation in the entire cohort [0.83 (0.71, 1.08) vs 0.74 (0.62, 1.33), P = 0.55]. There was no difference between the median (IQR) SCr (mg/dL) from day 1 through day 7 in patients that had no DFI [1.04 (0.89, 2.56) vs 1.20 (0.79, 2.92), P = 0.84]. Conclusion: No statistically significant change in SCr was observed over time in critically ill patients receiving IV methocarbamol regardless of DFI use.