Comparison of the side effects and gastrointestinal motility observed after administration of erythromycin and josamycin to dogs.

The effects of intravenous erythromycin and josamycin on gastrointestinal motility in dogs have been compared. Erythromycin interrupted the basal motility pattern in the fasted state and induced irregular bursts of spikes in both the fasted and fed states. Emesis occurred in all the dogs in the fasted state experiments and in four out of six dogs in the fed state experiments. Josamycin did not disturb gastrointestinal motility and no dog showed signs of discomfort. The difference in the chemical structure of erythromycin and josamycin is the main reason for their differential effect on the gastrointestinal tract.