This is a Phase 0, open-label, non-controlled, single-centre study designed to evaluate the pharmacokinetics (PK) and safety and tolerability of a single, bolus intravenous (iv) injection of a microdose of ACD856 in healthy subjects.

Inclusion Criteria:

• Healthy males aged >18 and <65 years.
• Signed and dated informed consent prior to any study-mandated procedure
• Willing and able to comply with study requirements.
• BMI >18.0 and <30.0 kg/m^2
• Male subjects must be willing to use condom or be vasectomised or practice sexual abstinence to prevent pregnancy and drug exposure of a partner and refrain from donating sperm from the date of dosing until 3 months after dosing with the IMP.
• Clinically normal medical history, physical findings, vital signs, ECG and laboratory values at the time of screening, as judged by the Investigator.

Exclusion Criteria:

• History of any clinically significant disease or disorder which may either put the subject at risk because of participation in the study, or influence the results or the subject's ability to participate in the study.
• Any planned major surgery within the duration of the study.
• Clinically relevant findings in laboratory parameters, ECG or vital signs at screening
• History of severe allergy/hypersensitivity or ongoing allergy/hypersensitivity
• Regular use of any prescribed or non-prescribed medication
• Planned treatment or treatment with another investigational drug within 3 months
• Current smokers or users of nicotine products.
• Positive screen for drugs of abuse or alcohol at screening
• History of alcohol abuse or excessive intake of alcohol
• Presence or history of drug abuse
• History of, or current use of, anabolic steroids.
• Excessive caffeine consumption
• Plasma donation within one month of screening or blood donation during the 3 months prior to screening.