Muscle Relaxants
Panel findings and recommendations:
- Muscle relaxants are an option in the treatment of patients with low back problems. While probably more effective than placebo, muscle relaxants have not been shown to be more effective than NSAIDs. (
Strength of Evidence = C.)
- No additional benefit is gained by using muscle relaxants in combination with NSAIDs over using NSAIDs alone. (
Strength of Evidence = C)
- Muscle relaxants have potential side effects, including drowsiness in up to 30 percent of patients. When considering the optional use of muscle relaxants, the clinician should balance the potential for drowsiness against a patient's intolerance of other agents. (
Strength of Evidence = C.)
Muscle relaxants are commonly used for the treatment of low back problems. Pharmacologically, these are usually benzodiazepines, other sedative medications, or antihistamine derivatives. The therapeutic objective of muscle relaxants is to reduce low back pain by relieving muscle spasm. However, the concept of skeletal muscle spasm is not universally accepted as a cause of symptoms, and the most commonly used muscle relaxants have no peripheral effect on muscle spasm.
Muscle Relaxants
Muscle Relaxants
Literature Reviewed. Of 42 articles screened for this topic, 12 RCTs met review criteria for adequate evidence about efficacy.
91,
104,
105,
106,
107,
108,
109,
110,
111,
112,
113,
114
Evidence on Efficacy. Three studies evaluating patients with low back problems either did not specify duration of symptoms or included a mix of patients with acute and chronic problems.
104,
113,
114 The remaining nine studies evaluated only patients with acute low back problems.
Of the articles that met review criteria, 9 evaluated a muscle relaxant compared with a placebo. 91,
104,
105,
108
,
109,
110,
111,
112,
113, Two studies compared two different muscle relaxants.
107,
114 Some of the studies also compared a muscle relaxant to another medication, including a barbiturate;
110,
111 an NSAID; 91,
106 and acetaminophen.91
Of the nine studies comparing muscle relaxants with placebos, seven had results favoring the muscle relaxant.
104,
105,
108,
109,
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113 Two showed no difference in outcomes between muscle relaxant and placebo. 91,
112 In most studies, the positive effect for muscle relaxants was short-lived, lasting no more than 4 to 7 days, with no significant difference from placebo seen after this time.
Panel methodologists did a meta-analysis of the 12 studies that met panel review criteria. The studies were assessed for quality without knowledge of the results. There was one excellent study,
107 three good studies,
105,
109,
114 and eight fair studies. 91,
104,
106,
108,
109,
110,
111,
112,
113
Each study was examined for outcome measures such as pain, functional capacity, or a global measure of improvement. When meta-analytically combined, the studies showed a trend toward greater improvement in the patients treated with muscle relaxants, but did not reach statistical significance. Even if the findings had reached significance, statistical combinations of such study results should be interpreted with caution. The conclusion of the meta-analysis was that muscle relaxants are probably, but not certainly, more effective than placebos in decreasing symptoms of low back problems. However, there was not enough evidence to determine whether muscle relaxants are more or less effective than NSAIDs for reducing symptoms or whether the addition of a muscle relaxant adds to the efficacy of an NSAID.
Potential Harms and Costs. Potential complications of muscle relaxants include drowsiness and dizziness, reported to be up to 30 percent higher in patients taking muscle relaxants compared with patients taking placebos. 91,
104,
105,
108,
109,
110,
111,
112,
113 The cost of muscle relaxants is considered low to moderate.
[A more recent review pooling 222 patients found tetrazapam 50mg TID for 14 days, statistically better than placebo but at best clinically marginal in reducing pain. Efficacy seems similar for different types of muscle relaxants and the adverse effects of muscle relaxants in the management of non-specific low back pain suggests caution use and discouraged long term use (vanTulder,`03).]
Summary of Findings. There is moderate research evidence that muscle relaxants are more effective than placebo, but no evidence that they are better than NSAIDs, in relieving symptoms of low back problems. These medications have substantial potential side effects, especially a high incidence of drowsiness.
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