Buprenorphine-Fentanyl Interaction Study

The study will be performed in 2 parts. Part A is a 3-period study; the first 2 periods have a single-blind, placebo-controlled, cross-over design, where subjects will be randomized in a 1:1 ratio to 2 treatment sequences determined by the order in which they receive buprenorphine or matching placebo. Period 3 is an open-label design where the same subjects will receive buprenorphine only. This period is optional, and will include approximately 6 subjects.

Part B is an open-label study in opioid tolerant patients. All will receive placebo plus fentanyl in Period 1 to permit dose escalation to full respiratory effects of fentanyl before assessing the interaction with buprenorphine. Subjects will receive buprenorphine plus fentanyl during Period 2 to assess the interaction with buprenorphine.

To study ventilation, the dynamic end-tidal forcing technique will be used. This technique enables the Investigator to force end-tidal partial pressure of carbon dioxide and end-tidal partial pressure of oxygen to follow a specific pattern in time. Subjects with a procedure-related adverse event (AE) will be treated according to established ventilatory support and opioid reversal protocols.