Abuse deterrence testing: A dose ratio escalation study examining naloxone coadministered with intravenous hydromorphone in non-treatment-seeking, opioid-dependent drug users.

OBJECTIVE: To assess the reduction in intravenous (IV) abuse potential of hydromorphone from different dose ratio combinations with naloxone in opioid-dependent drug users.

DESIGN: Randomized, blinded, dose ratio escalation study.

SETTING: Single center.

PARTICIPANTS: Following conversion to a stable IV dose of hydromorphone, 12 non-treatment-seeking, opioid-dependent subjects were randomly assigned and received at least one dose of study drug; seven subjects received all five study treatments. Five subjects withdrew early from the treatment phase: adverse events (2) and participant decision (3).

INTERVENTIONS: Participants underwent a dose-selection phase to stabilize on an individualized hydromorphone dose. Stable subjects were dosed intravenously on 5 consecutive days. The dose received was one of five hydromorphone/naloxone dose ratios that included the combination of hydromorphone and placebo naloxone. Hydromorphone/naloxone treatment always involved increasing dose ratios of naloxone (8:1, 6:1, 4:1, and 2:1) with the hydromorphone-placebo naloxone treatment randomly assigned within the sequence of dose ratios.

MAIN OUTCOME MEASURES: Drug Liking visual analog scale (VAS), Objective Opioid Withdrawal Scale (OOWS) and Subjective Opioid Withdrawal Scale (SOWS).

RESULTS: Hydromorphone/naloxone placebo produced subjective effects typical of opioid administration, while hydromorphone/naloxone dose ratios were associated with significant increases in SOWS and OOWS scores (p < 0.05). Compared with hydromoprophone/naloxone placebo, naloxone reduced the effects of hydromorphone on most measures, including Drug Liking VAS, the antagonism was greatest for the 4:1 and 2:1 ratios.

CONCLUSIONS: This study was an ethical investigation of the abuse deterrence potential of four hydromorphone/naloxone dose ratios. The IV coadministration of commercially available IV solutions of hydromorphone and naloxone in 4:1 and 2:1 ratios had statistically greater reductions of abuse-related opioid effects and triggers of withdrawal symptoms and there was a convergence of subjective and objective pharmacodynamic results and safety findings. An oral modified-release product, developed with a 2:1 hydromorphone/naloxone ratio, may have important public health benefits by reducing high-risk, IV abuse of prescription opioids, while providing pain relief when ingested orally and used in accordance with the Product Monograph.