Abuse of prescription
opioids has risen precipitously in the United States. Few controlled comparisons of the abuse liability of the most commonly abused
opioids have been conducted. This outpatient study employed a double-blind, randomized, within-subject, placebo-controlled design to examine the relative abuse potential and potency of oral
oxycodone (10, 20 and 40 mg),
hydrocodone (15, 30 and 45 mg),
hydromorphone (10, 17.5 and 25mg) and placebo. Healthy adult volunteers (n=9) with sporadic
prescription opioid abuse participated in 11 experimental sessions (6.5h in duration) conducted in a hospital setting. All three
opioids produced a typical mu
opioid agonist profile of subjective (increased ratings of liking, good effects, high and
opiate symptoms), observer-rated, and physiological effects (
miosis, modest
respiratory depression,
exophoria and decrements in visual threshold discrimination) that were generally dose-related. Valid relative potency assays revealed that
oxycodone was roughly equipotent to or slightly more potent than
hydrocodone.
Hydromorphone was only modestly more potent (less than two-fold) than either
hydrocodone or
oxycodone, which is inconsistent with prior estimates arising from
analgesic studies. These data suggest that the abuse liability profile and relative potency of these three commonly used
opioids do not differ substantially from one another and suggest that
analgesic potencies may not accurately reflect relative differences in abuse liability of prescription
opioids.