Effect of erythromycin lactobionate on myoelectric activity of ileum, cecum, and right ventral colon, and cecal emptying of radiolabeled markers in clinically normal ponies.

Objective: To determine the effect of erythromycin lactobionate (ERY) on ileocecocolic myoelectric activity and passage of radiolabeled markers from the cecum.
Animals: 6 healthy adult ponies.
Procedure: After a 12-hour nonfeeding period, 370 MBq of technetium 99m-labeled sulfur colloid in egg albumen and 37 MBq of indium 111-labeled diethyltriaminepentaacetic acid in 60 ml of water were administered directly into the cecal apex. The following drug concentrations were tested: ERY, 0.01, 0.10, 1.0, and 10.0 mg/kg of body weight; ERY, 0.10 mg/kg bolus; and saline (0.9% NaCl) solution, 10 ml. All treatments, with the exception of the 0.10-mg/kg bolus and saline solution, were infusions administered i.v. during a 60-minute period in a randomized complete block design. Each treatment was administered 2 times/pony. Dual-phase scintigraphic images were obtained, and the best-fit function was determined for each study, using data from the right side. Myoelectric data were collected before and after each treatment and analyzed for spike burst rate, relative activity, and burst duration.
Results: The time to 50% emptying (t50) after ERY administration was dose dependent, and all treatments, with the exception of the 0.01-mg/kg infusion, resulted in a significantly shorter t50 than that observed after saline administration (230.2 +/- 17.12 minutes). The shortest t50 was observed after the 1.0 mg/kg dosage of ERY (76.9 +/- 22.0 minutes). Although not significantly different, the t50 and beta were shorter (108.6 +/- 25.9 minutes) and steeper after a bolus dose of 0.10 mg/kg of ERY than after infusion at the same dosage (131.1 +/- 18.7 minutes).
Conclusions and Clinical Relevance: ERY may be a useful prokinetic for prevention or treatment of cecal motility dysfunction. The ability of ERY to evoke a similar response during the early postanesthetic or postoperative period remains to be determined.