Antidiarrheal agents/therapy

Antidiarrheal agents may be used safely in patients with mild to moderate acute diarrhea. However, these agents should not be used in patients with bloody diarrhea, high fever, or systemic toxicity because of the risk of worsening the underlying condition. They should be discontinued in patients whose diarrhea is worsening despite therapy. Antidiarrheals are also used to control chronic diarrhea caused by such conditions as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD). 

Cases of deliberate overdosage are unknown, but excessive duration or dosage of therapy will produce life-threatening toxicity because of the hematological effects and other symptoms and signs that are qualitatively similar to the adverse effects. There is no specific antidote to fluorouracil toxicity treatment consists of supportive care, including G-CSF and antidiarrheal agents. 

Diphenoxylate is an antidiarrheal agent. Diphenoxylate, related to meperidine, decreases motility of the GI tract. Atropine discourages deliberate overdosage of diphenoxylate. The combination is indicated as adjunctive therapy in the treatment of diarrhea. 

In initial studies, up to 35% of patients experienced severe diarrhea. Adoption of an intensive loperamide (see Chapter 38) regimen (4 mg of loperamide starting at the onset of any loose stool beginning more than a few hours after receiving therapy, followed by 2 mg every 2 hours) has effectively reduced this incidence by more than half. However, once severe diarrhea does occur, standard doses of antidiarrheal agents tend to be ineffective, although the diarrhea episode generally resolves within a week and, unless associated with fever and neutropenia, is rarely fatal. 

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