Comparison of the effect of azithromycin versus erythromycin on antroduodenal pressure profiles of patients with chronic functional gastrointestinal pain and gastroparesis

Background: Current pharmacologic treatments for gastroparesis have been disappointing due to the limited options available. Erythromycin ethylsuccinate is a potent prokinetic agent that stimulates gastric emptying. Recently, erythromycin has been linked to the occurrences of sudden cardiac death due to QT prolongation. Azithromycin is similar to erythromycin in structure but does not have significant drug-drug interactions as seen with erythromycin. Purpose: This study aims to determine whether azithromycin stimulates antral activity in patients with chronic gastrointestinal pain and refractory gastroparesis. Methods: Small bowel manometric data on 30 patients undergoing clinical evaluation for chronic digestive problems or documented refractory gastroparesis were reviewed. Antral activity was measured after infusion of erythromycin 250 mg intravenous and azithromycin (500 or 250 mg intravenous) given at different intervals during the small bowel manometry. The parameters measured included the total duration of effect, mean amplitude of antral contractions, duration of the highest antral contraction phase, number of cycles per minute, and the motility index. Results: Comparison of erythromycin and azithromycin at similar doses showed a similar positive effect on antral activity. However, comparison of erythromycin and azithromycin at the higher dose of 500 mg showed that the mean amplitude, duration of antral activity, and motility index were significantly increased with azithromycin (P < 0.05). Conclusions: Azithromycin stimulates antral activity similar to erythromycin and moreover has a longer duration of effect. However, unlike erythromycin, azithromycin does not have significant drug-drug interactions and may be a potential new medication for the treatment of gastroparesis and gastrointestinal dysmotility.