Stimulant laxatives, also known as irritant cathartics, include:
· castor oil
Stimulant laxatives are minimally absorbed and are metabolized in the liver. The metabolites are excreted in urine and stool.
Stimulant laxatives promote peristalsis and produce a bowel movement by irritating the intestinal mucosa or stimulating nerve endings of the intestinal smooth muscle.
Castor oil also increases peristalsis in the small intestine.
Stimulant laxatives are the preferred drugs for emptying the bow-el before general surgery, sigmoidoscopic or proctoscopic proce-dures, and radiologic procedures such as barium studies of the GI tract.
They’re also used to treat constipation caused by prolonged bed rest, neurologic dysfunction of the colon, and constipating drugs such as opioids.
No significant drug interactions occur with the stimulant laxa-tives. However, because these laxatives produce increased intesti-nal motility, they reduce the absorption of other oral drugs admin-istered at the same time, especially sustained-release forms. (See Adverse reactions to stimulant laxatives.)