Review Article: Drug Approval for Gastroparesis-Suggestions for Improving the Process for Positive Results

In the United States, metoclopramide is the only medication approved for gastroparesis. There is a need to reappraise the main considerations involved in the approval of pharmacological treatments of gastroparesis.

We conducted a literature review to address issues that might impact the approval of medications for gastroparesis. We appraised the epidemiology, clinical presentations, variations in diagnostic tests, and their thresholds for identification of gastroparesis. Based on the review, we proposed trial designs for proof of efficacy and safety of novel medications for gastroparesis.

Based on epidemiological studies, the age-adjusted prevalence in US population is 152,005 for all categories (definite, probable and possible) of gastroparesis. The major symptoms of gastroparesis are nausea, vomiting, early satiety and postprandial fullness and may lead to hospitalisation or emergency department visits. It is essential to appraise gastric emptying with a solid meal over at least 3 h using scintigraphy or a stable isotope breath test. Diagnostic thresholds have been established for these diagnostic tests and at present, reproducibility, normative data, and coefficient of variation are well established for the 320-kcal real egg solid meal. Based on published guidelines on clinical efficacy of medications used in gastroparesis, we propose targeting the gastroparesis symptom subscales, such as nausea and vomiting, with pharmacological agents specifically directed at their causative mechanisms rather than targeting the underlying dysmotility.

The evidence documented here justifies consideration of gastroparesis as an orphan disease, as well as an innovative approach to supplement the regulatory bodies' recommendations and guidance to industry. We propose treatment trials of 4-weeks duration and considering the use of specific symptoms of gastroparesis as clinical endpoints based on a pharmaceutical agent's mechanism of action, rather than using a total gastroparesis symptom score. Such an approach would include evidence of safety and efficacy of new medications targeting gastroparesis subscales, and approval for marketing would be based on the symptoms specifically ameliorated in robust trials.