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Manual Muscle Testing: A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients
Published on: April 12, 2011
Anticholinergic Adverse Effects Associated With Skeletal Muscle Relaxants in the Intensive Care Unit.
Justin P Reinert1,2, Jordyn Maroszek1, Rose Sikorski1
1The University of Toledo College of Pharmacy and Pharmaceutical Sciences, OH, USA.
Summary
Centrally acting muscle relaxants like cyclobenzaprine and methocarbamol are linked to anticholinergic adverse drug events in intensive care unit (ICU) patients. While these events occurred, they rarely led to medication discontinuation, suggesting cautious use in multimodal analgesia.
Area of Science:
- Pharmacology and Critical Care Medicine
- Drug Safety and Adverse Event Monitoring
Background:
- Pain is common in critically ill patients, often underrecognized due to sedation and mechanical ventilation.
- Opioids are standard ICU analgesics, but adverse effects drive interest in multimodal strategies.
- Limited data exist on anticholinergic adverse drug events (ADEs) of cyclobenzaprine and methocarbamol in ICU settings.
Purpose of the Study:
- To determine the prevalence of anticholinergic ADEs associated with cyclobenzaprine and methocarbamol in ICU patients.
- To analyze the types of ADEs, drug dosing, and discontinuation rates for these muscle relaxants.
Main Methods:
- Retrospective cohort study of adult ICU patients receiving cyclobenzaprine or methocarbamol.
- Data collected from January 1, 2023, to January 31, 2025, at a single academic medical center.
- Primary outcome: prevalence of anticholinergic ADEs identified via provider documentation and ICD-10 codes.
Main Results:
- 260 patients analyzed; 112 received cyclobenzaprine (43%) and 148 received methocarbamol (57%).
- Anticholinergic ADEs occurred in 14.4% of cyclobenzaprine recipients and 10.8% of methocarbamol recipients.
- Most ADEs (79%) led to interventions, primarily medication adjustments; discontinuation was infrequent.
Conclusions:
- Cyclobenzaprine and methocarbamol are associated with anticholinergic adverse effects in critically ill patients.
- These ADEs did not frequently result in medication discontinuation.
- Supports cautious use of these muscle relaxants in multimodal analgesia, with pharmacists playing a key role in monitoring.
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