Study of Promethazine for Treatment of Diabetic Gastroparesis

A Pilot, Randomized, Double-blind, Placebo-controlled Trial of Promethazine for Treatment of Diabetic Gastroparesis.

Adult diabetic patients (ages 18-65) with gastric emptying scintigraphy-confirmed delayed gastric emptying will be recruited to participate in the study. Using double-blinded methodology, study participants will be randomly assigned to one of two treatment arms: promethazine 12.5 mg three times daily for 28 days or placebo three times daily for 28 days. The primary outcome will be the change in gastroparesis symptom severity, as measured by the Gastroparesis Cardinal Symptom Index (GCSI) at four weeks compared to baseline. Participants will be seen for a clinic evaluation at weeks 0, 2 and 4, during which symptom scores, adverse events and treatment compliance will be assessed. It is hypothesized promethazine treatment will be superior to placebo in improving symptoms of gastroparesis.

Inclusion Criteria:

• adult patients 18-65 years of age
• clinical diagnosis of diabetic gastroparesis.
• EGD without evidence of gastric outlet obstruction within the past five years
• gastric emptying scintigraphy test demonstrating >10% solid food retention at 4 hours within the past three years.

Exclusion Criteria:

• the inability or unwillingness to provide informed consent
• currently pregnant or breast feeding
• prior placement of a gastric stimulator
• pyloric botulinum toxin injection within the past 12 months
• prior gastric surgery
• history of a connective tissue disorder
• use of narcotic medication within the past four weeks
• hemoglobin A1C >12 mg/dL within the past 3 months
• current or recent (within past 4 weeks) use of promethazine, metoclopramide or domperidone
• hypersensitivity or prior adverse reaction to promethazine
• concomitant use of phenothiazines (i.e. prochlorperazine, chlorpromazine) or other agents likely to increase extrapyramidal reactions
• concomitant use of tiotropium or ipratropium
• narrow angle glaucoma
• urinary retention
• Parkinson's disease
• significant psychiatric disease
• history of seizure.