Oxycodone induced euphoria in ED patients with acute musculoskeletal pain. A secondary analysis of data from a randomized trial

Endogenous opiates and behavior: 2022

This paper is the forty-fifth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2022 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Opioid analgesic effects on subjective well-being in the operating theatre

Exposure to opioid analgesics due to surgery increases the risk of new persistent opioid use. A mechanistic hypothesis for opioids' abuse liability rests on the belief that, in addition to pain relief, acute opioid treatment improves well-being (e.g. via euphoria) and relieves anxiety. However, opioids do not consistently improve mood in laboratory studies of healthy non-opioid users. This observational study determined how two commonly used opioid analgesics affected patients' subjective well-being in standard clinical practice. Day surgery patients rated how good and how anxious they felt before and after an open-label infusion of remifentanil (n = 159) or oxycodone (n = 110) in the operating theatre before general anaesthesia. One minute after drug injection, patients reported feeling intoxicated (> 6/10 points). Anxiety was reduced after opioids, but this anxiolytic effect was modest (remifentanil Cohen's d = 0.21; oxycodone d = 0.31). There was moderate to strong evidence against a concurrent improvement in well-being (Bayes factors > 6). After remifentanil, ratings of 'feeling good' were significantly reduced from pre-drug ratings (d = 0.28). After oxycodone, one in three participants felt better than pre-drug. Exploratory ordered logistic regressions revealed a link between previous opioid exposure and opioid effects on well-being, as only 14 of the 80 opioid-naïve patients reported feeling better after opioid injection. The odds of improved well-being ratings after opioids were higher in patients with previous opioid exposure and highest in patients with > 2 weeks previous opioid use (adjusted OR = 4.4). These data suggest that opioid-induced improvement of well-being is infrequent in opioid-naïve patients. We speculate that peri-operative exposure could increase risk of persistent use by rendering subsequent positive opioid effects on well-being more likely.

Use of clinical phenotypes to characterize emergency department patients administered intravenous opioids for acute pain

OBJECTIVE

Individual experience with opioids is highly variable. Some patients with acute pain do not experience pain relief with opioids, and many report no euphoria or dysphoric reactions. In this study, we describe the clinical phenotypes of patients who receive intravenous opioids.

METHODS

This was an emergency department-based study in which we enrolled patients who received an intravenous opioid. We collected 0 to 10 pain scores prior to opioid administration and 15 minutes after. We also used 0 to 10 instruments to determine how high and how much euphoria the patient felt after receipt of the opioid. Using a cutoff point of ≥50% improvement in pain and the median score on the high and euphoria scales, we assigned each participant to one of the following clinical phenotypes: pain relief with feeling high or euphoria, pain relief without feeling high or euphoria, inadequate relief with feeling high or euphoria, and inadequate relief without feeling high or euphoria.

RESULTS

A total of 713 patients were enrolled, 409 (57%) of whom reported not feeling high, and 465 (65%) reported no feeling of euphoria. Median percent improvement in pain was 37.5% (interquartile range, 12.5%-60.0%). One hundred seventy-eight participants (25%) were classified as experiencing pain relief with euphoria or feeling high, 190 (27%) experienced inadequate relief with euphoria or feeling high, 101 (14%) experienced pain relief without euphoria or feeling high, and 244 (34%) reported inadequate relief without euphoria or feeling high.

CONCLUSION

Among patients who receive intravenous opioids in the emergency department, the experiences of pain relief and euphoria are highly variable. For many, pain relief is independent of feeling high.