Muscle Relaxant Guidelines

Introduction to Muscle Relaxants

Muscle relaxants have non-specific effects and may inhibit polysynaptic myogenic reflexes, but their relationship to pain relief remains unclear, according to the American Geriatrics Society 1
The American Geriatrics Society recommends considering baclofen for spasticity from central nervous system injury or demyelinating conditions 1

Sedation and dizziness are primary concerns with muscle relaxant use, as reported by the American College of Physicians 2, 3
Increased risk of falls, particularly in older adults, is associated with muscle relaxant use, as noted by the American Geriatrics Society 1
Certain muscle relaxants, such as carisoprodol, have been removed from European markets due to abuse concerns, according to the American Geriatrics Society 1
Some muscle relaxants, like cyclobenzaprine, have anticholinergic effects, while others, like dantrolene, have a black box warning for potentially fatal hepatotoxicity, as reported by the American College of Physicians 2

Cyclobenzaprine is structurally similar to tricyclic antidepressants and has anticholinergic effects, such as dry mouth, according to the American Geriatrics Society 1
Carisoprodol is metabolized to meprobamate, which is associated with abuse and overdose, as reported by the American College of Physicians 2
Tizanidine and chlorzoxazone are associated with hepatotoxicity, usually reversible, according to the American College of Physicians 2
Dantrolene has a black box warning for potentially fatal hepatotoxicity, as noted by the American College of Physicians 2

The American College of Physicians recommends limiting muscle relaxant use to short periods only (2-3 weeks maximum) 2
The American Geriatrics Society advises avoiding muscle relaxants in older adults when possible due to increased risk of falls 1
Muscle relaxants should not be prescribed in the mistaken belief that they relieve muscle spasm, as they do not directly relax muscles despite their name, according to the American Geriatrics Society 1
The treatment duration should be limited to short-term relief (≤21 days) when possible, as recommended by the Society for Perioperative Assessment and Quality Improvement (SPAQI) consensus 4

Muscle relaxants are efficacious for acute low back pain in multiple trials, according to the American College of Physicians 5
Benzodiazepines are associated with the highest risk of sedation and central nervous system events, and should be avoided for muscle spasm when possible due to risks of dependence and more pronounced sedation, as recommended by the American College of Physicians 3
Methocarbamol should be ordered as an adjunct medication for acute painful musculoskeletal conditions with muscle spasm, but should not be used as a first-line agent, particularly in older adults, according to the American Geriatrics Society 6
Cyclobenzaprine can be prescribed at a dose of 5-10 mg three times daily for short-term use (up to 2-3 weeks) in patients with post-operative jaw pain, as recommended by the American Geriatrics Society and the American Association for the Study of Liver Diseases 5, 7

Methocarbamol is contraindicated in significant liver and kidney disease, and in myasthenia gravis, with a strength of evidence rated as high 4
Cyclobenzaprine is contraindicated in patients taking MAO inhibitors or within 14 days of discontinuing MAOIs, acute recovery phase of myocardial infarction, heart block, conduction disturbances, or arrhythmias, and hyperthyroidism, as recommended by the American Heart Association 5
Co-prescribing cyclobenzaprine with benzodiazepines is contraindicated due to the increased risk of respiratory depression and mortality, as warned by the FDA 7

Post-operative pain management involves a multimodal approach, including non-opioid analgesics, regional anesthesia techniques, and adjuvant medications, as recommended by the American Society of Anesthesiologists 8
Acetaminophen (IV or oral) is recommended to reduce opioid requirements and improve pain control, with a strength of evidence rated as high, according to the American Society of Anesthesiologists 8
NSAIDs like ibuprofen (800 mg IV every 6 hours) are recommended to decrease morphine requirements and pain scores, with a strength of evidence rated as moderate, as stated by the American Society of Anesthesiologists 8
Epidural and regional anesthesia are recommended when feasible, with a strength of evidence rated as high, according to the American Society of Regional Anesthesia and Pain Medicine 8
Patient-controlled analgesia (PCA) is recommended for superior pain control compared to continuous infusion, with a strength of evidence rated as moderate, as stated by the American Society of Anesthesiologists 8

A multimodal approach is recommended for managing pelvic pain, including muscle relaxants for pain associated with muscle spasm, as well as physical therapy, proper hydration, and appropriate analgesics, according to the National Comprehensive Cancer Network (NCCN) guidelines 9
Muscle relaxants can be used as a second-line treatment for the muscle spasm component of pelvic pain, while antiepileptic drugs (gabapentin, pregabalin) and tricyclic antidepressants or SNRIs can be used for the neuropathic component and central sensitization, respectively 9, 10
Pelvic floor muscle training (PFMT) is recommended for urinary bladder spasms or overactive bladder, as stated by the American College of Physicians and American Urological Association 11
Bladder training is recommended for urinary bladder spasms or overactive bladder, as stated by the American College of Physicians and American Urological Association 11
Antimuscarinic medications, such as darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine, and trospium, are recommended if bladder training is unsuccessful, with the choice based on tolerability, adverse effect profile, ease of use, and cost 11