The purpose of this study is to assess the pharmacokinetic (PK), metabolism, and routes of excretion of aticaprant and its metabolites in excreta and in plasma after a single oral dose 14C-aticaprant in healthy adult male participants.

Inclusion Criteria:

• Healthy on the basis of physical examination, medical history (screening only), vital signs, and electrocardiogram (ECG) performed at screening and admission to the study site on Day -1. Minor abnormalities in ECG, which are not considered to be of clinical significance by the investigator, are acceptable
• Body weight not less than 50 kilograms (kg) and body mass index (BMI; weight [kg]/height^2 [m^2]) within the range of 18.0 to 29.9 kilogram per meter square (kg/m^2) (inclusive)
• Blood pressure (after the participant is supine for 5 minutes) between 90 millimeters of mercury (mmHg) and 140 mmHg systolic, inclusive, and no higher than 90 mmHg diastolic at screening and Day -1
• A 12-lead ECG consistent with normal cardiac conduction and function, at screening and Day -1, including: sinus rhythm; pulse rate between 40 and 100 beat per minutes (bpm), extremes included; QTc interval less than or equal to (<=) 450 milliseconds (ms) for men; QRS interval of less than (<) 120 ms; PR interval < 210 ms; morphology consistent with healthy cardiac conduction and function
• Non-smokers (not smoked for 3 months prior to screening)

Exclusion Criteria:

• History of malignancy within 5 years before screening (exceptions are squamous and basal cell carcinomas of the skin, or malignancy, which is considered cured with minimal risk of recurrence)
• Known allergies, hypersensitivity, or intolerance to aticaprant or its excipients
• History of clinically significant (example: in the opinion of the investigator) drug and/or food allergies
• Participant has presence of left bundle branch block, atrioventricular block (second degree or higher), or a permanent pacemaker or implantable cardioverter defibrillator
• Anatomical (nasal) abnormalities which may make the placement of the nasoduodenal tube difficult (only for participants with duodenal sampling)

The data sharing policy of the Janssen Pharmaceutical Companies of Johnson & Johnson is available at www.janssen.com/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu