Effect of anthraquinone derivatives on canine and rat intestinal motility

The effects on gastrointestinal motility of 3 senna preparations containing 18% oxidized Ca-sennosides, 60% Ca-sennosides, or pure sennosides A + B were tested in dogs and rats as measured by electromyography. Oral administration of the oxidized products in the fasted animal increased the activity of the small intestine within 2 h and reduced both caecal and colonic contractions for 24 h. Severe diarrhoea was present 4-6 h after administration and lasted for at least 1 day. Ca-sennosides had a similar, but weaker effect while pure sennosides affected motility only 6-10 h after oral administration. The intracolonic administration of the oxidized products resulted in an immediate reduction of colon motility for 7-8 h and diarrhoea was present within 40 min. Intracolonic Ca-sennosides and sennosides A + B induced only small changes in the intestinal motility, but diarrhoea also appeared. The results confirm that pure sennosides act predominantly on large intestine motility after their degradation by colonic microorganisms. Oxidized products are already effective in the upper gastrointestinal tract. The early action of Ca-sennosides requires further investigation. Side effects after oral senna treatment such as griping or nausea may be caused by motility changes induced by the presence of small amounts of oxidized products in the drug.