Muscle Relaxants Baclofen and Tizanidine Tied to Higher Injury Risk in Older Adults: Study
USA: Older adults prescribed baclofen or tizanidine for musculoskeletal conditions face a higher risk of injury compared to those taking cyclobenzaprine, a recent retrospective cohort study published in the Journal of the American Geriatrics Society has shown.
The findings suggest that these medications, often considered alternatives to cyclobenzaprine, may not be safer options for older patients and could warrant inclusion in future updates of the Beers Criteria for potentially inappropriate medications.
The study, led by Dr. Monique M. George from the Kaiser Permanente Woodland Hills Family Medicine Residency, analyzed electronic health records from an integrated healthcare system in southern California. Researchers included adults aged 65 to 99 who were prescribed baclofen, tizanidine, or cyclobenzaprine between 2008 and 2018. The study examined injury-related hospitalizations, emergency department visits, and urgent care encounters, focusing on fractures, falls leading to fractures, brain injuries, and dislocations.
The cohort consisted of 87,896 participants with 118,426 medication episodes, of which 54.8% involved baclofen, 6.3% tizanidine, and 38.9% cyclobenzaprine. Over the study period, 1,987 injury events were recorded, with fractures being the most common (923 cases), followed by falls leading to fractures (773 cases), and other injuries (291 cases).
Key Findings:
- Baclofen was associated with a 69% increased risk of composite injury outcomes compared with cyclobenzaprine (aHR 1.69).
- Baclofen carried a 98% higher risk of falls leading to fracture (aHR 1.98).
- Baclofen showed a 37% higher risk of fractures (aHR 1.37).
- Baclofen was linked to a 150% increased risk of brain or dislocation injuries (aHR 2.50).
- Tizanidine was associated with a 34% higher risk of composite injury outcomes (aHR 1.34).
- Tizanidine carried a 58% increased risk of falls leading to fracture (aHR 1.58).
The study also identified other factors that independently increased the likelihood of injury, including a history of falls, Parkinson’s disease, kidney failure, and concurrent use of antidepressants. Injury-free probabilities over time were lower for both baclofen and tizanidine compared with cyclobenzaprine, reinforcing the heightened risk associated with these medications.
These results carry important clinical implications. The 2023 American Geriatrics Society (AGS) Beers Criteria already recommend avoiding most skeletal muscle relaxants in older adults due to safety concerns, but baclofen and tizanidine are currently excluded. “Our findings indicate that baclofen and tizanidine do not represent safer alternatives to cyclobenzaprine for older adults with musculoskeletal complaints and should be considered for inclusion in future iterations of the AGS Beers Criteria,” the authors noted.
While the study benefits from a large integrated health system dataset, its retrospective design and potential for residual confounding remain limitations. The findings emphasize the importance of careful prescribing of muscle relaxants in older adults, emphasizing the need for awareness of injury risks when considering baclofen or tizanidine in this population.
"The study highlights that older adults receiving baclofen or tizanidine face significantly higher injury risks compared to cyclobenzaprine, suggesting that these drugs should be prescribed with caution and considered for inclusion as potentially inappropriate medications in geriatric guidelines," the authors concluded.
Reference:
George, M. M., Deamer, R. L., Lee-Rodriguez, S., Jafari, J., Zhang, J., Chung, J., Bitar, D. M., & Adams, E. Safety of Baclofen and Tizanidine in Older Adults: A Retrospective Cohort Study in a Large Integrated Health Care System. Journal of the American Geriatrics Society. https://doi.org/10.1111/jgs.70097
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