Photo Credit: iStock.com/Ivan Kyryk
Research shows long-term skeletal muscle relaxant (SMR) use may only help patients with certain pain syndromes, and vigilance in SMR prescribing is warranted.
The long-term use of muscle relaxant medications may only help patients with certain chronic pain syndromes, according to results from a systematic review published in JAMA Network Open.
“Long-term use of [skeletal muscle relaxants (SMRs)] for chronic pain may be beneficial for patients with painful spasms or cramps and neck pain; evidence was equivocal for their long-term use for low back pain, fibromyalgia, and headaches,” Benjamin J. Oldfield, MD, MHS, and colleagues wrote.
In recent years, prescriptions for SMRs have grown in response to stricter opioid prescribing guidelines, the researchers noted. They conducted a systematic review of 30 randomized controlled trials and 14 cohort studies to investigate the effectiveness/efficacy of long-term use of SMRs for chronic pain. The studies included a total of 2,482 participants.
Most studies lasted from 4 to 6 weeks. The most common SMRs studied were baclofen (11 studies), tizanidine (8 studies), and cyclobenzaprine (7 studies), but eperisone, quinine, carisoprodol, orphenadrine, chlormezanone, and methocarbamol were also included.
Studies Assess Fibromyalgia, Headaches & More
Among the 44 studies, five focused on low back pain, 11 on fibromyalgia or related disorders, 10 on headaches or trigeminal neuralgia, 10 on painful muscle cramps or spasticity, and eight on other pain syndromes such as osteoarthritis, cervical spondylosis, neuropathy, cancer pain, gastric reflux–related pain, and orchialgia.
According to the researchers’ findings, evidence for effectiveness was strongest for SMRs in patients with trigeminal neuralgia, neck pain, and painful cramps. For fibromyalgia, low back pain, headaches, and other syndromes, “some [studies] showed small benefits and some did not, and on balance studies did not suggest a benefit,” Dr. Oldfield and colleagues wrote.
Sedation and dry mouth were the most common adverse effects of SMRs. None of the studies assessed SMR misuse.
The risk of bias in the included randomized controlled trials was low to moderate and commonly manifested as a lack of blinding of participants, personnel, and outcome assessments. The quality of the included cohort studies was fair to good.
“This summary of the evidence raises concerns given the growth in SMR prescriptions over the last decade, including for more than one in six patients seeking care for chronic back pain in a national study of Medicare beneficiaries,” the researchers wrote. “Clinicians should be vigilant for adverse effects and consider deprescribing if pain-related goals are not met.”
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