Opium Tincture Against Chronic Diarrhea - Healthy

The purpose of this study is to investigate the mechanistic anti-propulsive effects of opium tincture on the gastrointestinal tract of a cohort of healthy participants.

Opium tincture is used a symptomatic drug against chronic diarrhea even though no clinical studies have investigated the effect on gastrointestinal function. With this randomized, double-blind, placebo-controlled cross-over trial in 20 healthy participants, the investigators wish to provide evidence-based insights into the effects of opium tincture on gastrointestinal function. Additionally, effects on the central nervous system will be investigated a tertiary aim.

Eligibility Criteria:
Inclusion Criteria:

* Signed informed consent before any study specific procedures
* Able to read and understand Danish
* Male or female with an age of 20 years or more
* The researcher believes that the participant understands what the study entails, are capable of following instructions, can attend when needed, and are expected to complete the study.
* The investigator will ensure that fertile female participants have a negative pregnancy test before each treatment visit and use contraception during the entity of the study.
* Opioid naïve (in this study "opioid naïve" is defined as a person who does not have a history of opioid use/addiction. If the opioids were used more than five years before the start of experiment as an analgesic to treat pain post-surgery etc., this person will be considered opioid naïve. If the person has never used opioids to treat pain but has participated in pain studies where opioids were given more than a year before this experiment, this person will be considered opioid naïve)
* Healthy (assessed by a study-affiliated medical doctor)

Exclusion Criteria:

* Known allergy towards pharmaceutical compounds similar to Dropizol.
* Participation in other studies within 14 days of first visit (1 year if opioids involved).
* Expected need of medical/surgical treatment during the study
* History of psychiatric illness (e.g. mental retardation, schizophrenia, affective disorders (depression), personality disorders or treatment with psychoactive medications)
* History of substance abuse (e.g. alcohol, nicotine, tetrahydrocannabinol (THC), benzodiazepine, central stimulants and/or opioids)
* Family history of substance abuse
* Known increased intracranial pressure
* Known major stenosis of the intestines
* Planned MRI within the next 3 months
* Metal implants or pacemaker
* Known severe decreased renal function (defined as estimated glomerular filtration rate (eGFR) below 45)
* Known severe decreased hepatic function (defined as Child-Pugh class B or higher)
* Treatment with Monoamine oxidase (MAO) inhibitors during the entity of the study
* Known severe chronic obstructive pulmonary disease (COPD) or acute severe asthma (defined as forced expiratory volume in 1 second (FEV1) below 50 % or acute ongoing exacerbation)
* Known cor pulmonale
* Female participants that are lactating
* Medicine known to affect gastrointestinal motility must not be initiated during the entity of the study
* Use of any analgesic medication within 48 hours before start as well as for the duration of the study (urine drug test will be performed prior to treatment start).
* Intake of alcohol within 48 hours before start of study period as well as for the duration of the study.