The aim of the study is to determine the effect of dexmedetomidine infusion on gastric emptying and oro-caecal transit time in healthy volunteers, judged by measuring plasma paracetamol concentrations after paracetamol ingestion and pulmonary hydrogen measurement technique after lactulose ingestion. The effects of dexmedetomidine will be compared to the effects of morphine and placebo.

Inclusion Criteria:

• Normal cognitive function and fluent skills in the Finnish language in order to be able to give informed consent and communicate with the study personnel
• Age ≥ 18 years.
• Male gender.
• Weight ≥ 60 kg.
• Written informed consent from the subject.

Exclusion Criteria:

• Previous history of intolerance to the study drugs or related compounds and additives.
• Concomitant drug therapy of any kind except ibuprofen in the 14 days prior to the study days.
• Existing or recent significant disease.
• History of haematological, endocrine, metabolic or gastrointestinal disease.
• History of asthma or any kind of drug allergy.
• Previous or present alcoholism, drug abuse, psychological or other emotional problems that are likely to invalidate informed consent, or limit the ability of the subject to comply with the protocol requirements.
• A positive test result for urine toxicology.
• A "yes" answer to any of the questions in a modified Finnish version of the Abuse Questions
• Donation of blood within six weeks prior to and during the study.
• Special diet or lifestyle factors which would compromise the conditions of the study or the interpretation of the results.
• BMI > 30 kg / m2.
• Participation in any other clinical study involving investigational or marketed drug products concomitantly or within one month prior to the entry into this study.
• Smoking during one month before the start of the study or during the study period.
• Clinically significant abnormal findings in physical examination, ECG or laboratory screening [routine haematology (haemoglobin, haematocrit, red blood cell count, white blood cell count, platelets), renal function tests (creatinine, urea) and liver function tests (bilirubin)].