Effect of Cannabinoid Agonist on Gastrointestinal and Colonic Motor Functions in Patients With Irritable Bowel Syndrome (IBS)

Study Summary

Irritable bowel syndrome (IBS) affects about 15% of the U.S. population. There are still no effective and safe medications approved for the treatment of abdominal pain associated with bowel symptoms in IBS. This study will investigate the effects of an approved medication, Dronabinol, on the movement of food through the stomach and colon in subjects with a history of diarrhea-predominant Irritable Bowel Syndrome (D-IBS). Dronabinol is a synthetic medication (a medication made in a laboratory) related to the active ingredient of "cannabinoid or marijuana". Dronabinol is approved by the Food and Drug Administration (FDA) for preventing nausea and vomiting in patients with cancers undergoing chemotherapy. It is also used in AIDS patients with excessive weight loss for improvement in appetite and weight gain. The hypothesis in this study is that dronabinol will slow down the movement of food through the colon, and that this effect is regulated by the genes controlling the body messengers (receptors) that respond to medicinal marijuana or synthetic medicines that work on the same messengers that are present in the gastrointestinal tract and pain nerves.

Primary Outcome

The scintigraphic method is used to measure colonic transit. An isotope is adsorbed on activated charcoal particles and delivered to the colon in a delayed release capsule. Anterior and posterior gamma images are taken hourly. The geometric center (GC) is the weighted average of counts in the different colonic regions. The scale ranges from 1 to 5; a high GC implies faster colonic transit, a GC of 1 implies all isotope is in the ascending colon, and a GC of 5 implies all isotope is in the stool.

Interventions

• DRUG Placebo
• DRUG Dronabinol