Why are muscle relaxants advised against?

From the Guidelines

Muscle relaxants are generally advised against due to their limited effectiveness and significant side effects, as evidenced by the higher risk of adverse events, including central nervous system effects, compared to placebo 1. The main concerns with muscle relaxants include sedation, dizziness, and cognitive impairment, which can increase fall risk, especially in older adults. Some muscle relaxants also carry addiction potential, particularly carisoprodol (Soma), which converts to meprobamate, a controlled substance. Additionally, these medications can cause dry mouth, blurred vision, urinary retention, and may interact with other central nervous system depressants like alcohol or opioids, potentially causing dangerous respiratory depression. Key points to consider when evaluating the use of muscle relaxants include:

• Limited evidence for their efficacy in treating low back pain, with most studies showing only modest benefits 1
• Significant risks of adverse events, including central nervous system effects, compared to placebo 1
• Potential for addiction and abuse, particularly with carisoprodol (Soma) 1
• Availability of alternative approaches, such as physical therapy, exercise, heat therapy, and non-sedating pain relievers like acetaminophen or NSAIDs, which are typically recommended as first-line treatments. When muscle relaxants are prescribed, they should be used for the shortest duration possible, typically less than two weeks, to minimize risks while addressing acute symptoms 1.

From the FDA Drug Label

The development of a potentially life-threatening serotonin syndrome has been reported with Cyclobenzaprine Hydrochloride when used in combination with other drugs, such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), tramadol, bupropion, meperidine, verapamil, or monoamine oxidase (MAO) inhibitors. Cyclobenzaprine is closely related to the tricyclic antidepressants, e.g., amitriptyline and imipramine. In short term studies for indications other than muscle spasm associated with acute musculoskeletal conditions, and usually at doses somewhat greater than those recommended for skeletal muscle spasm, some of the more serious central nervous system reactions noted with the tricyclic antidepressants have occurred Tricyclic antidepressants have been reported to produce arrhythmias, sinus tachycardia, prolongation of the conduction time leading to myocardial infarction and stroke.

Muscle relaxants are advised against due to the risk of serious side effects, including:

• Serotonin syndrome: a potentially life-threatening condition that can occur when used in combination with other serotonergic drugs
• Central nervous system reactions: such as arrhythmias, sinus tachycardia, and prolongation of conduction time, which can lead to myocardial infarction and stroke 2
• Interaction with other drugs: cyclobenzaprine may enhance the effects of alcohol, barbiturates, and other CNS depressants 2

From the Research

Reasons to Advise Against Muscle Relaxants

• Muscle relaxants have been associated with various adverse effects, including drowsiness, dizziness, and fatigue 3, 4, 5.
• The use of skeletal muscle relaxants among older adults is associated with an increased risk of falls and injuries, with carisoprodol, methocarbamol, and cyclobenzaprine being particularly risky 6.
• There is limited evidence to support the use of muscle relaxants for pain management in certain conditions, such as rheumatoid arthritis 4.
• Some muscle relaxants, such as carisoprodol, have a potential for abuse 5.
• The efficacy of muscle relaxants is often dependent on their sedative effects, which can be dose-related 5.

Specific Muscle Relaxants to Avoid

• Carisoprodol: associated with an increased risk of injury in older adults and has a potential for abuse 5, 6.
• Methocarbamol: associated with an increased risk of injury in older adults 6.
• Cyclobenzaprine: associated with an increased risk of injury in older adults and can cause sedative effects 5, 6.
• Dantrolene: has been associated with rare serious hepatotoxicity 3.

Considerations for Alternative Treatments

• The use of alternative treatments, such as non-pharmacological therapies, should be considered for patients with acute and chronic pain 4, 7.
• Appropriate medication selection based on clinical indications is crucial to minimize adverse effects and maximize efficacy 7.