Which opioid adverse effect is most directly related to central nervous system depression?

Which opioid adverse effect is most directly related to central nervous system depression?

• A. Drowsiness/sedation
• B. Diarrhea
• C. Urinary retention
• D. Mydriasis

Answer: (A)

Opioids cause a range of adverse effects, but the one most directly tied to central nervous system depression is drowsiness or sedation. Activating mu receptors in the brain dampens neuronal activity in the brain’s arousal systems, especially the reticular activating system, leading to reduced alertness and wakefulness. This central dampening also underlies potential respiratory depression at higher doses. Other effects listed are driven by peripheral or autonomic actions (GI motility leading to constipation, bladder sphincter tone affecting urinary retention, and pupil changes that are not typical for opioids), so they don’t reflect central depressant activity as directly as sedation does.

Opioids cause a range of adverse effects, but the one most directly tied to central nervous system depression is drowsiness or sedation. Activating mu receptors in the brain dampens neuronal activity in the brain’s arousal systems, especially the reticular activating system, leading to reduced alertness and wakefulness. This central dampening also underlies potential respiratory depression at higher doses. Other effects listed are driven by peripheral or autonomic actions (GI motility leading to constipation, bladder sphincter tone affecting urinary retention, and pupil changes that are not typical for opioids), so they don’t reflect central depressant activity as directly as sedation does.