Commonly prescribed to relieve acute low back pain, muscle relaxants are, according to a new study, largely ineffective in the long term to treat low back pain.
- Antispasmodics and non-benzodiazepine antispasmodics may be prescribed for low back pain
- In low back pain, non-benzodiazepine antispasmodics reduce pain intensity after two weeks, but not significantly.
- However, this reduction in pain is no longer observed from the 3rd week of treatment.
- In addition, these drugs are associated with an increased risk of side effects.
- A large study strongly relativizes their effectiveness in case of acute pain in the lower back
Often called lumbago or simply back pain, acute low back pain is characterized by the occurrence of sharp pain in the lower part of the back just above the pelvis. It appears suddenly, generally following an effort to lift or rotate the back, and can be very intense: we sometimes speak of a feeling of “stabbing” in the back.
If the lumbago heals better by continuing to go about your activities, the prescription of muscle relaxants is common, including antispasmodics and non-benzodiazepine antispasmodics. Yet, according to a new study published in the BMJ, these muscle relaxants are not always effective in providing long-term relief for patients with acute low back pain.
No effects other than short term
These findings follow a meta-analysis of 31 studies looking at the effectiveness of muscle relaxants, involving more than 6,500 participants. The results suggest that in the first two weeks of treatment, non-benzodiazepine antispasmodics reduce acute low back pain more than in the control group. Antispasmodics work to reduce muscle spasms. Among this classification are non-benzodiazepine antispasmodics, which act on the patient’s spinal cord or brainstem. Examples are cyclobenzaprine, carisoprodol and metaxalone.
However, although these drugs show statistically significant results, the degree of certainty of their effectiveness is very low, points out the meta-analysis. The results show that their effect is too weak to reach clinical thresholds.
In addition, from the third to the thirteenth treatment, no reduction in pain was observed in the treated group compared to the control group. This suggests that non-benzodiazepine antispasmodics have an advantage over non-muscle treatments, but only within the first two weeks of treatment. Antispasmodic relaxants other than benzodiazepines, however, had little or no effect on pain, regardless of the duration of treatment.
Undesirable side effects
Another finding raised by the meta-analysis: taking antispasmodics other than benzodiazepines in the event of acute low back pain is associated with an increased risk of adverse effects, but not of serious effects, compared to a control group.
Thus, patients taking this type of treatment are more likely to discontinue it than patients taking non-benzodiazepine antispasmodics due to adverse treatment effects.
According to the authors, these findings, while significant, are unlikely to affect clinical practice due to the low certainty of the data. They plead, however, for the realization of“large, high-quality placebo-controlled trials” for “to resolve uncertainties regarding the efficacy and safety of muscle relaxants for lower back pain”.
“We encourage clinicians to discuss this uncertainty about the efficacy and safety of muscle relaxants with patients, sharing information about the possibility of a valid benefit in pain reduction but an increased risk of experience a non-serious adverse event, to enable them to make treatment decisions”they conclude.
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