Chronic Megacolon Medication

A high water intake is an essential measure. A minimum of 6-8 8-oz glasses a day is recommended.

Bulking agents, through the increase of fiber, are also important. Many agents are on the market for this purpose and typically contain psyllium husk or cellulose; each patient may respond differently to each agent. No single agent is superior to another.

Laxatives may be considered and continued if found to be helpful. The best laxatives for this purpose are osmotic agents, such as magnesium salts, sorbitol, or lactulose (the latter two may increase flatulence). Patients need encouragement to take sufficient amounts to produce a result. Stimulant laxatives are best left as a last resort because they may possibly induce deterioration in the ability of the colon to evacuate. Typical stimulant laxatives are senna and bisacodyl-containing medications. Many patients take natural herbal laxatives; these typically contain cascara.

Tegaserod, a 5HT4 agonist, was approved for use in chronic constipation and in women with constipation-predominant irritable bowel syndrome. Its role in chronic pseudo-obstruction had not been determined.

Tegaserod marketing was temporarily withdrawn from the US market in March 2007; however, as of July 27, 2007, restricted use of tegaserod is now permitted via a treatment investigational new drug (IND) protocol. The treatment IND protocol will allow tegaserod treatment of irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation (CIC) in women younger than 55 years who meet specific guidelines. Its use is further restricted to those in critical need who have no known or preexisting heart disease.

Earlier in 2007, tegaserod marketing was suspended because of a meta-analysis of safety data pooled from 29 clinical trials that involved more than 18,000 patients. The results showed an excess number of serious cardiovascular adverse events, including angina, myocardial infarction, and stroke, in those taking tegaserod compared with placebo. In each study, patients were assigned at random to either tegaserod or placebo. Tegaserod was taken by 11,614 patients, and placebo was taken by 7,031 patients. The average age of patients in these studies was 43 years, and most patients (ie, 88%) were women. Serious and life-threatening cardiovascular adverse effects occurred in 13 patients (0.1%) treated with tegaserod; among these, 4 patients had a heart attack (1 died), 6 had unstable angina, and 3 had a stroke. Among the patients taking placebo, only 1 (0.01%) had symptoms suggesting the beginning of a stroke that went away without complication.

For more information, see the FDA MedWatch Product Safety Alert.

Class Summary

Increase peristalsis of the intestine, reducing the time toxic substances remain in the lower GI tract.

Psyllium (Metamucil, Fiberall)

Promotes bowel evacuation by forming viscous liquid and perhaps by inducing peristalsis.

Magnesium hydroxide (Philips' Milk of Magnesia)

Causes osmotic retention of fluid, which distends the colon and probably increases peristaltic activity; promotes emptying of bowel.

Sorbitol

Hyperosmotic laxative that has cathartic actions in the GI tract.

Lactulose (Cephulac, Cholac, Constilac)

Produces osmotic effect in colon that results in distention and promotes peristalsis.

Senna (Senexon, Ex-Lax, Senokot, Senna-Gen, Black-Draught, Agoral)

Anthraquinone stimulant hydrolyzed by colonic bacteria into active compound. More potent than cascara sagrada and produces considerably more abdominal pain. Usually produces action 8-12 h after administration.

Bisacodyl (Bisac-Evac, Bisco-Lax, Dulcolax, Dacodyl)

Stimulates peristalsis, possibly by stimulating colonic intramural plexus. Alters water and electrolyte secretion, producing net intestinal fluid accumulation and laxation.

Cascara sagrada

Irritates intestinal mucosa, increasing rate of colonic motility and changes fluid and electrolyte secretion.

Polyethylene glycol (PEG) solution

For treatment of occasional constipation. In theory, less risk of dehydration or electrolyte imbalance with isotonic polyethylene glycol compared with hypertonic sugar solutions. Laxative effect generated because polyethylene glycol is not absorbed and continues to hold water by osmotic action through small bowel and colon, resulting in mechanical cleansing. In theory, less risk of dehydration or electrolyte imbalance with isotonic polyethylene glycol compared with hypertonic sugar solutions. The laxative effect is generated because polyethylene glycol is not absorbed and continues to hold water by osmotic action through the small bowel and the colon, resulting in mechanical cleansing. Supplied with measuring cap marked to contain 17 g of laxative powder when filled to the indicated line. May require 2-4 d (48-96 h) to produce bowel movement.