Gastrointestinal Elimination
7.6 Antidiarrheal Medications and Laxatives
There are three common mechanisms of action of antidiarrheal medications: adsorbents, which help eliminate the toxin or bacteria from the GI tract; antimotility agents, which slow peristalsis; and probiotics, which help to restore the normal bacteria found in the lower intestine. Nurses should closely monitor for dehydration; oral rehydration agents may be needed to replace fluid and electrolyte loss, but they do not treat diarrhea. Antibacterial agents may also be used to treat diarrhea caused by specific infections, such as campylobacter or giardia, but they are not routinely needed.[1]
When administering antidiarrheals, the nurse should document an abdominal assessment, frequency of bowel movements and stool characteristics, and if there is skin breakdown in the anal area. The nurse should also keep in mind that antidiarrheals should be used very cautiously with children because some categories are contraindicated.
Adsorbents
Adsorption is the adhesion of molecules to a surface. This process differs from absorption, where a substance is dissolved or penetrates into a surface. Bismuth subsalicylate (brand name Pepto Bismol) is an example of an adsorbent (see Figure 7.6a[2]).
Mechanism of Action Adsorbent medications work by coating the walls of the GI tract and binding the causative bacteria or toxin for elimination from the GI tract through the stool.[3] Bismuth subsalicylate also decreases the flow of fluids and electrolytes into the bowel, reducing inflammation within the intestine.[4]
Specific Administration Considerations Bismuth subsalicylate contains salicylate. It should be avoided if the client has an allergy to salicylates (including aspirin) or if the client is taking other salicylate products such as aspirin. It should not be used if the client has an ulcer, a bleeding problem, or bloody or black stool. For more information on salicylates, read Chapter 10.6. Children and teenagers who have or are recovering from chickenpox or flu-like symptoms should not use this product. When using this product, if changes in behavior with nausea and vomiting occur, consult a doctor because these symptoms could be an early sign of Reye’s syndrome, a rare but serious illness. Liquid products should be shaken well before use. Tablets should be swallowed whole and not chewed unless they are a chewable tablet. Medication can cause a black or darkened tongue. If symptoms worsen, a fever, or ringing in the ears occurs, or if diarrhea lasts longer than 48 hours, contact the provider. [5],[6]
Client Teaching & Education
Clients should be advised to take medication as directed. They should be aware of potential color changes to stool that may occur and that the medication contains aspirin. They should discontinue the medication if tinnitus occurs.[7]
Antimotility
Antimotility medications help to treat diarrhea by slowing peristalsis. There are two categories of antimotility medication: