Efficacy of Methocarbamol for Acute Pain Management in Young Adults With Traumatic Rib Fractures

Abstract

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; P = 0.01), and hospital LOS was also decreased (4 vs 3 days; P = 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.

Association Between Postoperative Methocarbamol and Postoperative Pain Opioid Dose Requirements

“…In the above-mentioned study by Deloney et al 8 and another study of rib fracture patients in which methocarbamol was administered at a median daily dose of 1500 mg for a median duration of 4 days, 11 methocarbamol was associated with a shorter length of hospital stay. This might be related to mitigation of pain-related muscle spasms of adjacent intercostal muscles.…”

“…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, respectively (Table 2). Length of hospital stay after surgery was 5 [4][5][6][7] (median [IQR]) mg, and 5 [4][5][6][7][8] days for methocarbamol and non-methocarbamol patients, respectively (Table 2).…”

“…Several previous studies evaluated the efficacy of methocarbamol on pain and analgesic requirement in surgical and trauma settings with mixed results 6–8,10,11 . For the surgical population, Looke et al evaluated the efficacy of intravenous methocarbamol in patients with total knee arthroplasty and hip arthroplasty 6 .…”

“…Mean pain scores on days 1, 2, and 3 were not different between the patients who received and did not receive methocarbamol, but the opioid consumption on day 1 was higher in patients who received methocarbamol than those who did not receive methocarbamol (62.9 MME vs. 38.9 MME). In rib fracture patients, Deloney et al demonstrated that methocarbamol started at 500 mg every 6 hours, which was titrated up to 1500 mg every 6 hours as part of a multimodal analgesia protocol consisting of scheduled acetaminophen, ibuprofen, and gabapentin did not decrease opioid consumption on day 1 and 2 after initiation of methocarbamol, but decreased opioid consumption on days 3 and cumulative opioid consumption during first 3 days (337 MME for non-methocarbamol patients versus 219 MME for methocarbamol patients) 8 . The study retrospectively compared before and after the implementation of the protocol including methocarbamol, but no adjustment of potential confounders was performed 8 …”

“…Among this class, methocarbamol has been most studied in the United States. Methocarbamol has been shown to decrease pain level and opioid dose requirements during 48 hours after total hip and knee arthroplasty, 6 decrease pain level immediately after breast augmentation, 7 and decrease opioid requirements during 3 days after hospital admission in patients with a rib fracture 8 . However, due to a small number of studies employing variable dosing regimens in various surgeries and trauma, the firm conclusion regarding the efficacy of methocarbamol in acute postoperative management could not be drawn.…”