Buspirone for Early Satiety and Symptoms of Gastroparesis

This study evaluates whether the study medication, buspirone, an antianxiety drug, improves the symptoms of gastroparesis in patients with gastroparesis symptoms and at least moderately severe symptoms of fullness and/or inability to eat a full meal. Half the patients will receive buspirone and half the patients will receive a placebo.

This is a multi-center, randomized, double-masked, placebo-controlled, parallel treatment groups phase 2 trial to determine the effect of buspirone, a 5-hydroxytryptamine (5-HT) 1a receptor agonist, on early satiety and postprandial fullness in participants with symptoms of gastroparesis and with at least moderately severe symptoms of early satiety and/or postprandial fullness. After enrollment, participants aged 18-75 years will be treated with buspirone (10 mg three times per day) or a matching placebo for 4 weeks, followed by a 2-week post-treatment washout period. The primary outcome for the study is 4-week change (week 4 minus baseline) in the 4-item postprandial fullness/early satiety subscore (higher scores indicate worse symptoms) from the Patient Assessment of Gastrointestinal Disorders Symptom Severity Index (PAGI-SYM) Gastroparesis Cardinal Symptom Index (GCSI). We hypothesize that buspirone treatment will improve symptoms of postprandial fullness/early satiety compared to treatment with placebo, as indicated by a lower (smaller, more negative) 4-week change in the postprandial fullness/early satiety subscore in the buspirone arm compared to the placebo arm; change for a participant will be calculated as subscore at 4-weeks minus subscore at baseline.

Eligibility Criteria:
Inclusion Criteria:

* Age 18 to 85 years of age at initial screening interview
* Symptoms compatible with gastroparesis or other functional gastric disorder for at least 3 months (does not have to be contiguous) prior to initial screening interview
* Diagnosis of either diabetic or idiopathic gastroparesis
* Delayed or normal gastric emptying retention on screening 4-hour Gastric Emptying Scintigraphy test
* Symptoms of gastroparesis measured by the 9-item PAGI-SYM Gastroparesis Cardinal Symptom Index (GCSI) total score \> 2.0 at enrollment
* Symptomatic with postprandial fullness/early satiety severity at enrollment using the PAGI-SYM GCSI post-prandial fullness/early satiety subscore ≥ 3
* Upper endoscopy or upper GI series without ulcers or mass lesions in the 2 years prior to enrollment

Exclusion Criteria:

* Post-surgical gastroparesis, including prior pyloromyotomy, pyloric resection, vagotomy, bariatric surgery or post-Nissen fundoplication
* Another active disorder which could explain symptoms in the opinion of the investigator
* Concurrent use of opiate narcotic analgesics more than 3 days per week
* Significant hepatic injury as defined by alanine aminotransferase (ALT) elevation of greater than twice the Upper Limit of Normal (ULN) or a Child-Pugh score of 10 or greater
* Significant renal impairment as defined by serum creatinine \> 3.0
* Uncontrolled diabetes defined as HbA1c (%) of 10% or more within 60 days of enrollment
* Allergy to buspirone
* Concurrent or prior use (within 30 days) of monoamine oxidase (MAO) inhibitors
* Concurrent or prior use (within 30 days) of benzodiazepines
* Concurrent or prior use (within 30 days) of buspirone, warfarin, haloperidol, and drugs to treat seizures (e.g., phenytoin and carbamazepine)
* Women breast feeding or known to be pregnant
* Any other condition, which in the opinion of the investigator would impede compliance or hinder completion of the study
* Failure to give informed consent