A Pilot Study on the Efficacy and Safety of Olanzapine in Gastroparesis

Gastroparesis is a disorder characterized by impaired gastric emptying in the absence of obstruction in the proximal GI tract. It is a common condition affecting up to 5 million persons in the United States alone. Despite this, metoclopramide is currently the only FDA approved medication for the treatment of gastroparesis. However, the evidence supporting metoclopramide in gastroparesis is fairly weak and was recently issued a black box warning because of potential irreversible side effects. There is clearly an urgent need for newer therapeutic options with better efficacy and tolerability. Olanzapine is a second generation anti-psychotic that is currently FDA approved for the treatment of schizophrenia and bipolar disorder. Because of actions at several receptors throughout the body, including dopamine and serotonin receptors, Olanzapine may provide anti-nausea and pro-motility effects in the stomach. Long-term use of olanzapine may also increase plasma levels of ghrelin. Ghrelin is a hormone produced by the gut that stimulates appetite and has also been shown to have beneficial effects on gastroparesis. The investigators hypothesize that olanzapine will be effective and safe in controlling symptoms as well as stimulate appetite and weight gain in gastroparesis. The investigators also hypothesize that olanzapine will stimulate gastric motility. Finally, the investigators hypothesize that olanzapine will modulate the secretion of ghrelin in gastroparesis. This pilot study may provide further information on the efficacy and safety of olanzapine in gastroparesis which could be utilized in a larger randomized, prospective study in the future.