A study to determine how the bodies of healthy study participants handle axelopran and oxycodone given as a combined tablet compared with given as separate tablets.

INTERVENTION: The interventional product, axelopran 10mg, will be co‐formulated with an oxycodone 20mg tablet and administered orally under fasting conditions. Both products will also be administered together but as separate tablets, and also as individual doses, so that study participants will each receive each of the 4 treatment options, separated by a week between dosing. In each Period, subjects will also receive co‐treatment with naltrexone 50 mg orally (a single 50 mg dose 15 and 3 hours before and 9 and 21 hours after dosing with Study Treatment). CONDITION: Opioid induced constipation PRIMARY OUTCOME: The primary outcome is to determine the relative bioavailability of axelopran and oxycodone (by assessment of plasma concentrations) after oral administration as a fixed‐dose combination compared to the individual components when administered together to healthy subjects under fasting conditions SECONDARY OUTCOME: To assess the safety of single doses of axelopran and oxycodone administered (through evaluation of vital signs (including blood pressure, temperature, respiratory rate and oxygen saturation), physical examination, electrocardiography, adverse events, and laboratory safety tests) as a fixed‐dose combination, co‐administered as individual components, and administered as separate treatments to healthy subjects under fasting conditions. The study will monitor for all adverse events, including events that might be related to axelopran or the opioid. Any adverse event (either new or an exacerbation of a pre‐existing condition) with an onset date after study drug administration will be recorded as an adverse event. The definition of an adverse event is defined as any untoward medical occurrence in a subject administered a pharmaceutical product and which does not necessarily have a causal relationship with the treatment. In addition to the vital sign and laboratory assessments listed above, trial subjects will be assessed by site staff and questioned on how they are feeling and any adverse signs or symptoms will be recorded as adverse events. To determine the relative bioavailability of axelopran and oxycodone when administered as individual, single ingredient drug products relative to when co‐administered either as the individual components or as a fixed‐dose combination INCLUSION CRITERIA: ‐ healthy weight, BMI, medical history and on physical exam ‐ females must not be pregnant and males and females must practice approved contraception during the study ‐ screening lab assessments must have normal healthy results ‐ able to comply with study requirements and give informed consent