Paw placement during walking is altered by analgesic doses of opioids and post-surgical injury in mice

Hind paw-directed assays are commonly used to study the analgesic effects of opioids in mice. However, opioid-induced hyper-locomotion can obscure results of such assays. We aimed to overcome this potential confound by using gait analysis to observe hind paw usage during walking in mice. We measured changes in paw print area following induction of post-surgical pain (using the paw incision model) and treatment with oxycodone. Paw incision surgery reduced the paw print area of the injured hind paw as the mice avoided placing the incised section of the paw on the floor. Surprisingly, oxycodone caused a tiptoe-like gait in mice, resulting in a reduced paw print area in both hind paws. Further investigation of this opioid-induced phenotype revealed that analgesic doses of oxycodone or morphine dose-dependently reduced hind paw print area in uninjured mice. The gait changes were not dependent on opioid-induced increases in locomotor activity; speed and paw print area had no correlation in opioid-treated mice, and other analgesic compounds that alter locomotor activity did not affect paw print area. Unfortunately, the opioid-induced 'tiptoe' gait phenotype prevented gait analysis from being a viable metric for demonstrating opioid analgesia in injured mice. However, this work reveals an important, previously uncharacterized effect of treatment with analgesic doses of opioids on paw placement. Our characterization of how opioids affect gait has important implications for the use of mice to study opioid pharmacology and suggests that scientists should use caution when using hind paw-directed nociceptive assays to test opioid analgesia in mice.

The opioid crisis: evaluating the safety and efficacy of opioid analgesia in the management of acute post-operative dental pain

The use and misuse of opioid analgesics have been highlighted in recent years. This review assesses dental opioid use, the effectiveness of opioid-containing analgesics versus non-opioid alternatives and the implications for post-operative pain management strategies in the dental practice. Guidelines for the management of acute post-operative dental pain differ from country to country. The UK has a low dental opioid use rate when compared to the US. The combination of paracetamol and ibuprofen has similar, if not better, analgesic properties compared to opioid-containing alternatives, with fewer adverse effects. CPD/Clinical Relevance: Non-opioid analgesics are both a safe and effective alternative to opioid analgesics in the management of post-operative dental pain.

Racial and Ethnic Disparities in Pain Management of Children With Limb Fractures or Suspected Appendicitis: A Retrospective Cross-Sectional Study

Objective: To evaluate whether racial/ethnical differences in analgesia administration existed in two different cohorts of children with painful conditions: children with either limb fracture or suspected appendicitis.Methods: Retrospective cross-sectional analysis of children visiting a pediatric emergency department (Boston Children Hospital) for limb fracture or suspected appendicitis from 2011 to 2015. We computed the proportion of children that received any analgesic treatment and any opioid analgesia. We performed multivariable logistic regressions to investigate race/ethnicity differences in analgesic and opioid administration, after adjusting for pain score, demographics and visit covariates.Results: Among the 8,347 children with a limb fracture and the 4,780 with suspected appendicitis, 65.0 and 60.9% received any analgesic treatment, and 35.9 and 33.4% an opioid analgesia, respectively. Compared to White non-Hispanic Children, Black non-Hispanic children and Hispanic children were less likely to receive opioid analgesia in both the limb fracture cohort [Black: aOR = 0.61 (95% CI, 0.50–0.75); Hispanic aOR = 0.66 (95% CI, 0.55–0.80)] and in the suspected appendicitis cohort [Black: aOR = 0.75 (95% CI, 0.58–0.96); Hispanic aOR = 0.78 (95% CI, 0.63–0.96)]. In the limb fracture cohort, Black non-Hispanic children and Hispanic children were more likely to receive any analgesic treatment (non-opioid or opioid) than White non-Hispanic children [Black: aOR = 1.63 (95% CI, 1.33–2.01); Hispanic aOR = 1.43 (95% CI, 1.19–1.72)].Conclusion: Racial and ethnic disparities exist in the pain management of two different painful conditions, which suggests true inequities in health care delivery. To provide equitable analgesic care, emergency departments should monitor variation in analgesic management and develop appropriate universal interventions.