Gastrointestinal Complications (PDQ®): Supportive care - Health Professional Information [NCI] - Constipation
Medical management includes the administration of saline or chemical laxatives, suppositories, enemas, or agents that increase bulk.
Rectal agents should be avoided in cancer patients at risk for thrombocytopenia, leukopenia, and/or mucositis from cancer and its treatment. In the immunocompromised patient, no manipulation of the anus should occur, that is, no rectal examinations, no suppositories, and no enemas. These actions can lead to the development of anal fissures or abscesses, which are portals of entry for infection. Also, the stoma of a patient with neutropenia should not be manipulated.
Medical Agents for Constipation
- Bulk producers are natural or semisynthetic polysaccharide and cellulose. They work with the body's natural processes to hold water in the intestinal tract, soften the stool, and increase the frequency of the passage of stool. Bulk producers are not recommended for use in a regimen to counteract the bowel effects of opioids.
- Onset: 12 to 24 hours (may be delayed up to 72 hours).
- Caution: Patients should take with two full 8-oz (240-mL) glasses of water and maintain adequate hydration to avoid the risk of developing a bowel obstruction. Avoid administering psyllium with salicylates, nitrofurantoin, and digitalis because psyllium decreases the actions of these drugs. Avoid use if intestinal obstruction is suspected.
- Use: Effective in managing irritable bowel syndrome.
- Drugs and dosages:
- Methylcellulose (Cologel): 5 to 20 cc 3 times per day with water.
- Barley malt extract (Maltsupex): Four tablets with meals and at bedtime or 2 tbsp powder or liquid 2 times per day for 3 to 4 days, then 1 to 2 tbsp at bedtime.
- Psyllium: Varies from 1 tbsp to one packet, depending on brand, 1 to 3 times per day.
- The high osmolarity of the compounds in saline laxatives attracts water into the lumen of the intestines. The fluid accumulation alters the stool consistency, distends the bowel, and induces peristaltic movement. Cramps may occur.
- Onset: 0.5 to 3 hours.
- Caution: Repeated use can alter fluid and electrolyte balance. Avoid magnesium-containing laxatives in patients with renal dysfunction. Avoid sodium-containing laxatives in patients with edema, congestive heart failure, megacolon, or hypertension.
- Use: Mostly as a bowel preparation to clear the bowels for rectal or bowel examinations.
- Drugs and dosages:
- Magnesium sulfate: 15 g in a glass of water.
- Milk of magnesia: 10 to 20 cc if concentrated, 15 to 30 cc if regular.
- Magnesium citrate: 240 cc.
- Sodium phosphate: 4 to 8 g dissolved in water.
- Monobasic and dibasic sodium phosphate (Fleet Phospho-soda): 20 to 40 mL mixed with 4 oz cold water.
- 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.