B Large Bowel Irritant Purgatives p 177 ff

Anthraquinone derivatives (p. 176) are of plant origin. They occur in the leaves (folia sennae) or fruits (fructus sennae) of the senna plant, the bark of Rhamnus frangulae and Rh. purshiana, (cortex frangulae, cascara sagrada), the roots of rhubarb (rhizoma rhei), or the leaf extract from Aloe species (p. 176). The structural features of anthraquinone derivatives are illustrated by the prototype structure depicted on p. 177. Among other substituents, the anthra-quinone nucleus contains hydroxyl groups, one of which is bound to a sugar (glucose, rhamnose). Following ingestion of galenical preparations or of the anthraquinone glycosides, discharge of soft stool occurs after a latency of 6 to 8 h. The anthraquinone glycosides themselves are inactive but are converted by colon bacteria to the active free agly-cones.

Diphenolmethane derivatives (p. 177) were developed from phenolphthalein, an accidentally discovered laxative, use of which had been noted to result in rare but severe allergic reactions. Bisac-odyl and sodium picosulfate are converted by gut bacteria into the active colon-irritant principle. Given by the enteral route, bisacodyl is subject to hydrolysis of acetyl residues, absorption, conjugation in liver to glucuronic acid (or also to sulfate, p. 38), and biliary secretion into the duodenum. Oral administration is followed after approx. 6 to 8 h by discharge of soft formed stool. When given by suppository, bisacodyl produces its effect within 1 h.

Indications for colon-irritant purgatives are the prevention of straining at stool following surgery, myocardial infarction, or stroke; and provision of relief in painful diseases of the anus, e.g., fissure, hemorrhoids.

Purgatives must not be given in abdominal complaints of unclear origin. 3. Lubricant laxatives. Liquid paraffin (paraffinum subliquidum) is almost non-absorbable and makes feces softer and more easily passed. It interferes with the absorption of fat-soluble vitamins by trapping them. The few absorbed paraffin particles may induce formation of foreign-body granulomas in enteric lymph nodes (paraffinomas). Aspiration into the bronchial tract can result in li-poid pneumonia. Because of these adverse effects, its use is not advisable.

Lubricant PurgativesFrangulae Cortex The MicroscopeOsmotic PurgativesLarge Bowel Irritant Laxatives
B. Large-bowel irritant laxatives: diphenylmethane derivatives
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