Intoxication and other subjective effects of preanesthetic opioids in surgical patients: A randomized controlled trial.
Siri Gurandsrud Karlsen, Isabell M Meier, Martin Trøstheim et al.
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In 30 seconds
This double-blind, randomized controlled trial assessed acute subjective effects of intravenous morphine (10 mg), oxycodone (5 mg), or fentanyl (0.1 mg) in 199 adults with ASA physical status I-II undergoing elective surgery. After standardized multimodal preoperative medication, patients rated their experiences before and 3 min after opioid administration. Undesirable effects—particularly intoxication, sedation, and dizziness—were prominent; 96% of patients reported feeling intoxicated, while only 23% reported feeling better. Fentanyl generally produced stronger subjective effects than morphine, with oxycodone intermediate.
Key findings
- Overall, 96% of patients reported feeling intoxicated after preanesthetic opioid administration.
- Only 23% of patients reported feeling better; reduced anxiety and increased relaxation were modest.
- Fentanyl produced higher ratings of intoxication, sedation, dizziness, and euphoria than morphine; oxycodone generally had intermediate effects.
- Substantial interindividual variability in subjective effects was observed across all treatment groups.
Why it matters
Preoperative opioids may be given with the aim of improving comfort, but this trial found that undesirable subjective effects were more prominent than reported benefits in the studied surgical population. The findings help clarify the immediate patient experience of these drugs and suggest that perceived comfort should not be assumed from opioid administration alone.
What to keep in mind
Subjective effects were assessed only 3 min after administration, so the study does not establish longer-term effects. Participants were adults with ASA physical status I-II undergoing elective surgery and received standardized multimodal preoperative medication.