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Emergency Medicine Journal : EMJ Jul 2023Acute low back pain (LBP) is a common complaint in the emergency department and achieving effective analgesia can be challenging. (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Acute low back pain (LBP) is a common complaint in the emergency department and achieving effective analgesia can be challenging.
METHODS
In this multicentre randomised double-blind clinical trial conducted at three EDs in Iran from August to November 2020, we assessed the efficacy and adverse effects of two muscle relaxants in patients aged 18 years or older who suffered LBP in the last 6 weeks. Group 1 received intravenous methocarbamol and group 2 received intravenous diazepam followed by a weight-based dose of intravenous morphine in both groups. Exclusion criteria mainly included non-spine aetiologies, cord compression, acute gastrointestinal bleeding, renal/hepatic insufficiency, pregnancy, breast feeding and unstable vital signs. Pain scores and adverse events were measured by a Numeric Rating Scale (NRS) at baseline and after 30 and 60 min by one of the researchers who was not involved with patient visits and was blinded to the intervention. We used -test to assess the mean difference of NRS at 30 and 60 min.
RESULTS
Out of 101 enrolled patients, 50 participants received methocarbamol and 51 diazepam. The baseline mean pain scores and demographic characteristics were not different between the study groups. Pain scores were reduced by both agents after 60 min, with slightly greater pain reductions in the diazepam group in comparison with methocarbamol (mean difference -6.1, 95% CI -6.5 to -5.7 vs mean difference -5.2, 95% CI -5.7 to -4.7, respectively, p<0.001). ED length of stay of patients did not differ between the groups (methocarbamol 5.9 vs diazepam 4.8 hours, p=0.365). Patients receiving diazepam were more likely to report drowsiness (2 (4.0%) vs 15 (29.4%), p=0.001).
CONCLUSIONS
In patients with LBP, the pain was relieved in the methocarbamol and diazepam groups after 60 min. Although diazepam was more effective, its use was associated with a slightly higher risk of drowsiness.
TRIAL REGISTRATION NUMBER
The protocol of this clinical trial was prospectively registered in the irct.ir (IRCTID: IRCT20151113025025N4; https://irct.ir/trial/50148) .
Topics: Humans; Methocarbamol; Diazepam; Low Back Pain; Treatment Outcome; Acute Pain; Emergency Service, Hospital; Double-Blind Method
PubMed: 37068928
DOI: 10.1136/emermed-2021-211485 -
American Family Physician Aug 2008Skeletal muscle relaxants are widely used in treating musculoskeletal conditions. However, evidence of their effectiveness consists mainly of studies with poor... (Review)
Review
Skeletal muscle relaxants are widely used in treating musculoskeletal conditions. However, evidence of their effectiveness consists mainly of studies with poor methodologic design. In addition, these drugs have not been proven to be superior to acetaminophen or nonsteroidal anti-inflammatory drugs for low back pain. Systematic reviews and meta-analyses support using skeletal muscle relaxants for short-term relief of acute low back pain when nonsteroidal anti-inflammatory drugs or acetaminophen are not effective or tolerated. Comparison studies have not shown one skeletal muscle relaxant to be superior to another. Cyclobenzaprine is the most heavily studied and has been shown to be effective for various musculoskeletal conditions. The sedative properties of tizanidine and cyclobenzaprine may benefit patients with insomnia caused by severe muscle spasms. Methocarbamol and metaxalone are less sedating, although effectiveness evidence is limited. Adverse effects, particularly dizziness and drowsiness, are consistently reported with all skeletal muscle relaxants. The potential adverse effects should be communicated clearly to the patient. Because of limited comparable effectiveness data, choice of agent should be based on side-effect profile, patient preference, abuse potential, and possible drug interactions.
Topics: Back Pain; Fibromyalgia; Humans; Neck Pain; Neuromuscular Agents; Treatment Outcome
PubMed: 18711953
DOI: No ID Found -
Muscle & Nerve Jan 2021The muscle relaxant methocarbamol is widely used for the treatment of muscle spasms and pain syndromes. To elucidate molecular mechanisms of its action, we studied its...
BACKGROUND
The muscle relaxant methocarbamol is widely used for the treatment of muscle spasms and pain syndromes. To elucidate molecular mechanisms of its action, we studied its influence on neuromuscular transmission, on isometric muscle force, and on voltage-gated Na channels.
METHODS
Neuromuscular transmission was investigated in murine diaphragm-phrenic nerve preparations and muscle force studied on mouse soleus muscles. Na 1.4 channels and Na 1.7 channels were functionally expressed in eukaryotic cell lines.
RESULTS
Methocarbamol, at 2 mM, decreased the decay of endplate currents, slowed the decay of endplate potentials and reduced tetanic force of soleus muscles. The drug reversibly inhibited current flow through muscular Na 1.4 channels, while neuronal Na 1.7 channels were unaffected.
CONCLUSIONS
The study provides evidence for peripheral actions of methocarbamol on skeletal muscle. Muscular Na channels are a molecular target of methocarbamol. Since Na 1.7 currents were unaffected, methocarbamol is unlikely to exert its analgesic effect by directly blocking Na 1.7 channels.
Topics: Action Potentials; Animals; Male; Methocarbamol; Mice, Inbred C57BL; Muscles; Neurons; Phrenic Nerve; Voltage-Gated Sodium Channels; Mice
PubMed: 33043468
DOI: 10.1002/mus.27087 -
The Clinical Journal of Pain Sep 2023We tested the hypothesis that patients who received methocarbamol postoperatively experience less severe pain and require smaller doses of opioids than those who did not...
OBJECTIVES
We tested the hypothesis that patients who received methocarbamol postoperatively experience less severe pain and require smaller doses of opioids than those who did not receive methocarbamol.
MATERIALS AND METHODS
This is a retrospective cohort study of patients undergoing surgery involving the musculoskeletal system. Of 9089 patients, 704 received methocarbamol during 48 hours postoperatively, while 8385 did not receive methocarbamol. The patients who received methocarbamol postoperatively and the patients who did not receive methocarbamol were compared on the time-weighted average (TWA) pain score and opioid dose requirements in morphine milligram equivalents (MME) during the first 48 hours postoperatively, using propensity score-weighted regression models to adjusting for preoperative and intraoperative covariates.
RESULTS
Postoperative 48-hour TWA pain scores were 5.5±1.7 (mean±SD), and 4.3±2.1 for methocarbamol and non-methocarbamol patients. Postoperative 48-hour opioid dose requirements in MME were 276 [170-347] (median [interquartile range (IQR)]) mg, and 190 [60-248] mg for methocarbamol and non-methocarbamol patients. In propensity score-weighted regression models, receiving methocarbamol postoperatively was associated with 0.97-point higher postoperative TWA pain score (95% CI, 0.83-1.11; P <0.001), and 93.6-MME higher postoperative opioid dose requirements (95% CI, 79.9 to 107.4; P <0.001), compared with not receiving methocarbamol postoperatively.
DISCUSSION
Postoperative methocarbamol was associated with significantly higher acute postoperative pain burden and opioid dose requirements. Although the results of the study are influenced by residual confounding, they suggest a limited-if any-benefit of methocarbamol as an adjunct of postoperative pain management.
Topics: Humans; Analgesics, Opioid; Retrospective Studies; Methocarbamol; Pain, Postoperative
PubMed: 37284760
DOI: 10.1097/AJP.0000000000001137 -
Journal of Pain and Symptom Management Aug 2004Skeletal muscle relaxants are a heterogeneous group of medications used to treat two different types of underlying conditions: spasticity from upper motor neuron... (Comparative Study)
Comparative Study Meta-Analysis Review
Skeletal muscle relaxants are a heterogeneous group of medications used to treat two different types of underlying conditions: spasticity from upper motor neuron syndromes and muscular pain or spasms from peripheral musculoskeletal conditions. Although widely used for these indications, there appear to be gaps in our understanding of the comparative efficacy and safety of different skeletal muscle relaxants. This systematic review summarizes and assesses the evidence for the comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions. Randomized trials (for comparative efficacy and adverse events) and observational studies (for adverse events only) that included oral medications classified as skeletal muscle relaxants by the FDA were sought using electronic databases, reference lists, and pharmaceutical company submissions. Searches were performed through January 2003. The validity of each included study was assessed using a data abstraction form and predefined criteria. An overall grade was allocated for the body of evidence for each key question. A total of 101 randomized trials were included in this review. No randomized trial was rated good quality, and there was little evidence of rigorous adverse event assessment in included trials or observational studies. There is fair evidence that baclofen, tizanidine, and dantrolene are effective compared to placebo in patients with spasticity (primarily multiple sclerosis). There is fair evidence that baclofen and tizanidine are roughly equivalent for efficacy in patients with spasticity, but insufficient evidence to determine the efficacy of dantrolene compared to baclofen or tizanidine. There is fair evidence that although the overall rate of adverse effects between tizanidine and baclofen is similar, tizanidine is associated with more dry mouth and baclofen with more weakness. There is fair evidence that cyclobenzaprine, carisoprodol, orphenadrine, and tizanidine are effective compared to placebo in patients with musculoskeletal conditions (primarily acute back or neck pain). Cyclobenzaprine has been evaluated in the most clinical trials and has consistently been found to be effective. There is very limited or inconsistent data regarding the effectiveness of metaxalone, methocarbamol, chlorzoxazone, baclofen, or dantrolene compared to placebo in patients with musculoskeletal conditions. There is insufficient evidence to determine the relative efficacy or safety of cyclobenzaprine, carisoprodol, orphenadrine, tizanidine, metaxalone, methocarbamol, and chlorzoxazone. Dantrolene, and to a lesser degree chlorzoxazone, have been associated with rare serious hepatotoxicity.
Topics: Clinical Trials as Topic; Comorbidity; Evidence-Based Medicine; Humans; Motor Neuron Disease; Muscle Spasticity; Musculoskeletal Diseases; Neuromuscular Agents; Peripheral Nervous System Diseases; Treatment Outcome
PubMed: 15276195
DOI: 10.1016/j.jpainsymman.2004.05.002 -
The Annals of Pharmacotherapy Jun 2021Rib fractures account for more than one-third of blunt thoracic injuries and are associated with serious complications. Use of nonopioid adjunctive agents such as... (Observational Study)
Observational Study
BACKGROUND
Rib fractures account for more than one-third of blunt thoracic injuries and are associated with serious complications. Use of nonopioid adjunctive agents such as methocarbamol for pain control has increased considerably.
OBJECTIVE
This study aimed to assess the impact of methocarbamol addition to the pain control regimen on daily opioid requirements for young adults with rib fractures.
METHODS
This observational, retrospective study included patients aged 18 to 39 years with 3 or more rib fractures who were admitted to a level 1 trauma center between July 2014 and July 2018. Patients were dichotomized based on admission before and after methocarbamol addition to the institutional rib fracture protocol. The primary outcome was to determine the impact of methocarbamol on daily opioid requirements. Secondary outcomes included hospital length of stay (LOS) and diagnosis of pneumonia.
RESULTS
A total of 50 patients were included, with 22 and 28 patients in the preprotocol and postprotocol groups, respectively. All patients in the latter group received methocarbamol, whereas no patient in the preprotocol group received methocarbamol. Cumulative opioid exposure was significantly less for patients admitted after methocarbamol addition to the protocol (219 vs 337 mg oral morphine equivalents; = 0.01), and hospital LOS was also decreased (4 vs 3 days; = 0.03). No significant differences in the incidence of pneumonia or adverse effects were observed.
CONCLUSION AND RELEVANCE
This is the first study to evaluate the impact of methocarbamol on reducing opioid requirements. Given the risks associated with opioids, use of methocarbamol as an analgesia-optimizing, opioid-sparing multimodal agent may be reasonable.
Topics: Analgesics, Opioid; Humans; Length of Stay; Methocarbamol; Pain Management; Retrospective Studies; Rib Fractures; Young Adult
PubMed: 33045839
DOI: 10.1177/1060028020964796 -
Industrial Medicine & Surgery Oct 1965
Topics: Adult; Female; Humans; Methocarbamol
PubMed: 5214208
DOI: No ID Found -
Muscle & Nerve Jul 2022The muscle relaxant methocarbamol and the antimyotonic drug mexiletine are widely used for the treatment of muscle spasms, myotonia, and pain syndromes. To determine...
INTRODUCTION/AIMS
The muscle relaxant methocarbamol and the antimyotonic drug mexiletine are widely used for the treatment of muscle spasms, myotonia, and pain syndromes. To determine whether these drugs affect muscle spindle function, we studied their effect on the resting discharge and on stretch-induced action potential frequencies of proprioceptive afferent neurons.
METHODS
Single unit action potential frequencies of proprioceptive afferents from muscle spindles in the murine extensor digitorum longus muscle of adult C57BL/6J mice were recorded under resting conditions and during ramp-and-hold stretches. Maximal tetanic force of the same muscle after direct stimulation was determined. High-resolution confocal microscopy analysis was performed to determine the distribution of Na 1.4 channels, a potential target for both drugs.
RESULTS
Methocarbamol and mexiletine inhibited the muscle spindle resting discharge in a dose-dependent manner with IC values around 300 μM and 6 μM, respectively. With increasing concentrations of both drugs, the response to stretch was also affected, with the static sensitivity first followed by the dynamic sensitivity. At high concentrations, both drugs completely blocked muscle spindle afferent output. Both drugs also reversibly reduced the specific force of the extensor digitorum longus muscle after tetanic stimulation. Finally, we present evidence for the presence and specific localization of the voltage-gated sodium channel Na 1.4 in intrafusal fibers.
DISCUSSION
In this study we demonstrate that both muscle relaxants affect muscle spindle function, suggesting impaired proprioception as a potential side effect of both drugs. Moreover, our results provide additional evidence of a peripheral activity of methocarbamol and mexiletine.
Topics: Animals; Methocarbamol; Mexiletine; Mice; Mice, Inbred C57BL; Muscle Spindles; Muscle, Skeletal; Neurons, Afferent
PubMed: 35373353
DOI: 10.1002/mus.27546