The stimulant cathartics contain a variety of drugs whose exact mode of action is not known, although it is thought that they act on the mucosa of the intestine to stimulate peristalsis either by irritation or by exciting reflexes in the myenteric plexuses. All act in the lumen of the GI tract and are inactive if given parenterally. They produce irritation of the mucosa if given in large doses, and this irritation affects water and ion transport. However, a direct local irritation may not be essential to their action. It has been suggested that these drugs may act by stimulating afferent nerves to initiate a reflex increase in gut motility.
Anthraquinone derivatives (e.g., cascara, aloe, senna, and rhubarb) are among the oldest laxatives known. They act on the colon rather than on the ileum and produce evacuation 8 to 10 hours after administration. This makes them particularly suitable for dosage overnight. Cascara sagrada is one of the mildest of the anthraquinone-containing laxatives.
Phenolphthalein is partially absorbed (about 15% of a given dose) and excreted into the bile; hence, if it is taken constantly, it will accumulate and exert too drastic an action. It inhibits active sodium and glucose absorption in the bowel. Once widely available in many over-the-counter products, it was pulled from the market when it was linked to cancer.
Castor oil is a bland oil that is hydrolyzed in the gut to yield ricinoleic acid, the active purging agent. This hydrolysis requires bile, a fact that is sometimes overlooked when castor oil is given as a laxative before radiography in biliary obstruction. The ricinoleic acid acts on the ileum and colon to induce an increased fluid secretion and colonic contraction.
Bisacodyl (Dulcolax) causes colonic contraction and inhibits water absorption in the small and large intestine.
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Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.