Dietary fiber and related bulk-forming laxatives
A high-fiber diet is the most natural way to
prevent or treat consti-pation. Dietary
fiber is the part of plants not digested in the small intestine.
Bulk-forming laxatives, which resemble dietary fiber, containnatural
and semisynthetic polysaccharides and cellulose. These laxatives include:
psyllium hydrophilic mucilloid.
Dietary fiber and bulk-forming laxatives aren’t
absorbed systemi-cally. The polysaccharides in these drugs are converted by
intesti-nal bacterial flora into osmotically active metabolites that draw water
into the intestine.
Dietary fiber and bulk-forming laxatives are
excreted in stool.
Dietary fiber and bulk-forming laxatives increase
stool mass and water content, promoting peristalsis.
Bulk-forming laxatives are used to:
§ treat simple cases of constipation,
especially constipation re-sulting from a low-fiber or low-fluid diet
§ aid patients recovering from acute myocardial
infarction (MI) or cerebral aneurysms who need to avoid Valsalva’s maneuver
(forced expiration against a closed airway) and maintain soft stool
§ manage patients with IBS and diverticulosis.
Decreased absorption of digoxin, warfarin, and
salicylates occurs if these drugs are taken within 2 hours of taking fiber or
bulk-forming laxatives. (See Adverse
reactions to dietary fiber and re-lated bulk-forming laxatives.)