Comparative cognitive and subjective side effects of immediate-release oxycodone in healthy middle-aged and older adults

Abstract

This study measured the objective and subjective neurocognitive effects of a single 10-mg dose of immediate-release oxycodone in healthy, older (> 65 years), and middle-aged (35 to 55 years) adults who were not suffering from chronic or significant daily pain. Seventy-one participants completed 2 separate study days and were blind to medication condition (placebo, 10-mg oxycodone). Plasma oxycodone concentration peaked between 60 and 90 minutes postdose (P < .01) and pupil size, an indication of physiological effects of the medication, peaked at approximately 90 to 120 minutes postdose (P < .01). Significant declines in simple and sustained attention, working memory, and verbal memory were observed at 1 hour postdose compared to baseline for both age groups with a trend toward return to baseline by 5 hours postdose. For almost all cognitive measures, there were no medication by age-interaction effects, which indicates that the 2 age groups exhibited similar responses to the medication challenge. This study suggests that for healthy older adults who are not suffering from chronic pain, neurocognitive and pharmacodynamic changes in response to a 10-mg dose of immediate-release oxycodone are similar to those observed for middle-aged adults.

Perspective: Study findings indicate that the metabolism, neurocognitive effects, and physical side effects of oral oxycodone are similar for healthy middle-aged and older adults. Therefore, clinicians should not avoid prescribing oral opioids to older adults based on the belief that older adults are at higher risk for side effects than younger adults.

Figure 1

Study flow outline.

Figure 2

Time course of mean and standard deviations of plasma concentrations of oxycodone and its metabolites noroxycodone, oxymorphone, noroxymorphone. Older adults are represented by dark circles and middle age group by open circles.

Figure 3

Mean pupil size in millimeters for Middle age subjects (black squares) and older subjects (open circles) at each study time point indicated by minutes on the X axis starting with baseline (BL) and continuing for each assessment indicated in minutes post oxycodone (10mg). Middle age subjects evidenced a significant decrease in pupil size at 90, 120 and 180 minutes and older adults at the same time points as well as 240, 300 and 360 minutes post oxycodone dose. All changes were significant at the p<0.01 level except for 240 and 360 timepoints for older adults (p<0.05).