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Gastrointestinal Complications (PDQ®): Supportive care - Health Professional Information [NCI] - Constipation

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Stimulant laxatives

  • Stimulant laxatives increase motor activity of the bowels by direct action on the intestines.
  • Onset: 6 to 10 hours.
  • Caution: Prolonged use of these drugs causes laxative dependency and loss of normal bowel function. Prolonged use of danthron discolors rectal mucosa and discolors alkaline urine red. Bisacodyl must be excreted in bile to be active and is not effective with biliary obstruction or diversion. Avoid bisacodyl with known or suspected ulcerative lesions of the colon. These medications may cause cramping.
  • Drug interactions: Avoid taking bisacodyl within 1 hour of taking antacids, milk, or cimetidine because they cause premature dissolving of the enteric coating, which results in gastric or duodenal stimulation. There is an increased absorption of danthron when it is given with docusate.
  • Use: To evacuate bowel for rectal or bowel examinations. Most of the stimulant laxatives act on the colon.
  • Drugs and dosages:
    • Danthron: 37.5 to 150 mg with evening meal or 1 hour after evening meal.
    • Calcium salts of sennosides: 12 to 24 mg at bedtime; senna: Senolax, Seneson, or Black-Draught (two tablets); Senokot (two tablets or 10–15 cc at bedtime).
    • Bisacodyl: 10 to 15 mg swallowed whole, not chewed, or a 10-mg suppository.

Lubricant laxatives

  • Lubricant laxatives lubricate intestinal mucosa and soften stool.
  • Caution: Administer on empty stomach at bedtime. Mineral oil prevents absorption of oil-soluble vitamins and drugs. With older patients, aspiration potential suggests that mineral oil be avoided because it can cause lipid pneumonitis. It can interfere with postoperative healing of anorectal surgery. Avoid giving with docusate sodium. Docusate sodium causes increased systemic absorption of mineral oil.
  • Use: Prophylactically to prevent straining in patients for whom straining would be dangerous.
  • Drugs and dosages:
    • Mineral oil: 5 to 30 cc at bedtime.

Fecal softeners

  • Fecal softeners promote water retention in the fecal mass, thus softening the stool. Up to 3 days may pass before an effect is noted. Stool softeners and emollient laxatives are of limited use because of colonic resorption of water from the forming stool.
  • Fecal softeners are not used as the sole regimen but may be useful given in combination with stimulant laxatives.
  • Caution: May increase the systemic absorption of mineral oil when administered together.
  • Use: Prophylactically to prevent straining. Most beneficial when stool is hard.
  • Drugs and dosages:
    • Docusate sodium: 50 to 240 mg taken with a full glass of water.
    • Docusate calcium: 240 mg each day until bowel movement is normal.
    • Docusate potassium: 100 to 300 mg each day until bowel movement is normal; increase daily fluid intake.
    • Poloxamer 188: 188 mg (480 mg at bedtime).
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