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Objective: To compare the subjective effects of oxymorphone extended release (OM-ER ) versus oxycodone controlled release (OC-CR ).Design: Randomized, double-blind, crossover study.Setting: Inpatient unit.Subjects: Healthy, nondependent recreational opioid users.Interventions: Single intact oral tablets that were placebo or contained OM-ER (15 and 30 mg) or OC-CR (30 and 60 mg). Doses were representative of mid-range doses for chronic pain and were calculated using an established opioid conversion table.Main outcome measures: Visual Analog Scales, Subjective Drug Value (SDV), and Addiction Research Center Inventory (ARCI) measured positive, negative, and balance effects and pupillometry. Equianalgesic comparisons were between OM-ER 15 mg versus OC-CR 30 mg (low doses) and OM-ER 30 mg versus OC-CR 60 mg (high doses).Results: Thirty-five subjects received all five treatments. Positive subjective effects were lower for OM-ER 15 mg versus OC-CR 30 mg and for OM-ER 30 mg versus OC-CR 60 mg in ARCI Morphine Benzedrine Group (p ≤ 0.01 for both), Good Effects (p < 0.001 for both), Rush (p < 0.001 for both), and High VAS (p < 0.001 for both). Nausea was higher with OC-CR (p ≤ 0.02), and Bad Effects were higher for OC-CR 60 mg versus OM-ER 30 mg (p < 0.001). Balance effects were lower for OM-ER versus OC-CR (Drug Liking, p < 0.001; Overall Drug Liking, p ≤ 0.006; SDV, p ≤ 0.008), except for Take Drug Again (p < 0.001 for OC-CR 30 mg versus OM-ER 15 mg; p = 0.18 for high-dose group). Euphoric mood, nausea, somnolence, vomiting, and dizziness were more common with OC-CR than OM-ER.Limitations: Single-dose design; use of healthy, recreational opioid users.Conclusions: At equianalgesic doses, single oral intact OM-ER produced lower positive, negative, and balance subjective effects than OC-CR , indicating that analgesic potency may not necessarily be reflected in subjective/objective effects.