Sodium picosulfate is a triarylmethane group derivative stimulant laxative. After oral administration it is activated by the colonic bacteria and acts locally in the colon.The active form then stimulates the nerve endings of the intestinal wall and results in colonic peristalsis with promotion of accmulation of water and electrolytes in the colonic lumen.This results in stimulation of defecation, reducation of transit time and softening of the stool.Stimulation of the rectum causes increased motility and a feeling of rectal fullness. The rectal effect may help to restore the "call to stool"