Comparative study on effects of 14- and 16-membered macrolides on gastrointestinal motility in unanaesthetized dogs.

Comparative studies on the effects of 14-membered and 16-membered macrolides on gastrointestinal motility were conducted in unanaesthetized dogs. Midecamycin acetate, a new 16-membered macrolide, and leucomycin, another 16-membered macrolide, did not disturb the gastrointestinal motility and no dogs showed any adverse effects. In contrast, erythromycin stearate, erythromycin ethylsuccinate and triacetyloleandomycin, 14-membered macrolides, caused adverse effects such as strong contractile motility, nausea, vomiting and diarrhoea. The adverse effects of macrolides on the gastrointestinal tract are related to their chemical structure.