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.


Eligibility Criteria:
Inclusion Criteria:

* Male or female between 18 and 70 years of age
* Must have a \> or = 6 month history of relevant symptoms of gastroparesis, (e.g., chronic post-prandial fullness, early satiety, postprandial nausea), patients will have a mean of the daily scores over a minimum of 7 days indicating \> or = mild (2) and \< or = severe (4) post-prandial fullness assessed using the GCSI-DD during the screening period prior to randomization
* Documented abnormal gastric emptying within the past 2 years
* Has gastroparesis at screening (gastric half-time of emptying \> upper limit of normal as determined by wireless motility capsule)
* BMI between 18 - 30 kg/m2
* A female subject is eligible to participate if she is of non-childbearing potential or child-bearing potential and agrees to use one of the approved contraception methods. Female patients must agree to use contraception for at least 5 days following the last dose of study medication
* Subject has never had a gastrectomy, nor major gastric surgical procedure or any evidence of bowel obstruction or strictures within the previous 12 months
* Dosage of any concomitant medications has been stable for at least 3 weeks.
* Estimated (or measured) glomerular filtration rate ≥ 30 mL/min
* QTcB or QTcF \< 450 msec or QTc \< 480 msec in patients with Bundle Branch. Block based on single or average QTc value of triplicate values obtained over a brief recording period
* Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form
* AST and ALT \< 2xULN; alkaline phosphatase and bilirubin ≤ 1.5xULN; normal CBC, TSH, and prolactin levels

Exclusion Criteria:

* History of diabetes mellitus or hyperglycemia
* History of cardiovascular or cerebrovascular disease
* History of hyperlipidemia
* History of cardiac arrhythmia or long QT syndrome
* History of seizure disorder
* History of hyperprolactinemia
* History of renal dysfunction
* History of hepatic impairment
* History of schizophrenia, bipolar disorder, or previous use of olanzapine
* History of Parkinson's disease, dementia or severe cognitive impairment
* History of GI surgery or placement of gastric pacemaker
* History of cardiac pacemaker or implantable cardiac defibrillator
* History of eating disorder
* History of intrapyloric botulinum toxin injections
* Subject is on chronic enteral or parenteral feeding
* Subject has pronounced dehydration
* Subject has evidence of severe cardiovascular autonomic neuropathy (e.g. history of recurrent syncope in the last 6 months)
* Use of medications potentially influencing upper gastrointestinal motility or appetite within one week of the study (e.g., prokinetic drugs, macrolide antibiotics (erythromycin), GLP-1 mimetics)
* Regular opiate use
* Subjects who are taking drugs that potentially interact with olanzapine including diazepam, lorazepam, alcohol, carbamazepine, fluvoxamine, olanzapine and fluoxetine in combination, CNS acting drugs, levodopa and dopamine agonist, and olanzapine when used in combination with lithium or valproate
* History or presence of clinically significant gastro-intestinal, hepatic or renal disease or other condition that would in the opinion of the investigator or medical monitor make the subject unsuitable for inclusion in this clinical study
* The subject has participated in a clinical trial and has received an investigational product within the following time period prior to the first dosing day in the current study: 30 days, 5 half-lives or twice the duration of the biological effect of the investigational product (whichever is longer)
* History of sensitivity to any of the study medications, or components thereof or a history of drug or other allergy that, in the opinion of the investigator would make the subject unsuitable for inclusion in this clinical study
* Where participation in the study would result in donation of blood or blood products in excess of 500 mL within a 56 day time-period
* Pregnant females as determined by positive serum or urine hCG test (from the first urine of the day) at screening or prior to dosing
* Lactating females
* Current or chronic history of liver disease, or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones)
* Subject is unable to swallow pills