JC Pharmacology Wk 7 Chapter 40

Diarrhea

• Diarrhea means an increase in stool liquidity or frequency of defecation to more than 3 stools daily.
• It is a symptom of conditions that increase bowel motility, cause secretion or retention of fluids in the intestinal lumen, or cause irritation of the GI tract, leading to rapid propulsion of contents toward the rectum and limited absorption of fluids and electrolytes.

Diarrhea Causes

• Includes laxative abuse, drug therapy, undigested food in the GI tract, a lack of digestive enzymes, and intestinal infections.
• Can be caused by viruses, bacteria, and protozoa, improperly prepared meat or poultry consumption, and inflammatory bowel disorders.
• Irritable bowel syndrome, drugs, intestinal neoplasms, functional disorders, hyperthyroidism, surgical incisions of portions of the intestine (usually the small intestine), and HIV/AIDS can cause diarrhea.

Question #1

• Antibiotic-associated colitis is not is a mild condition caused by oral antibiotic therapy.
• Antibiotic-associated colitis is a serious condition due to the proliferation of pathogenic bacteria, specifically Clostridium difficile, because of antibiotic's suppression of normal flora in the colon.

Intestinal Infections

• Intestinal Infections can be caused by bacteria such as Escherichia coli, Salmonella, Shigella, and Clostridium difficile.
• Rotavirus and calicivirus are viruses which can cause intestinal infections.
• Giardia lamblia and Cryptosporidium parvum are protozoa which can cause intestinal infections.

Characteristics of Diarrhea

• Can be acute or chronic, mild or severe.
• Fever, vomiting, and bloody stools are associated with acute diarrhea, and the presence of these symptoms may help determine the cause.
• Most diarrhea episodes are the body trying to rid itself of irritants, toxins, and infectious agents.
• Diarrhea is usually self-limiting, subsiding within 24 to 48 hours.
• Severe or prolonged episodes may lead to serious fluid and electrolyte depletion, especially in young children and older adults.
• Chronic diarrhea may have remissions and exacerbations.

Question #2

• Alosetron is a selective 5-HT₃ receptor antagonist that is indicated for treating female with chronic severe diarrhea-predominant IBS that has not responded to conventional therapy.

Medications for Diarrhea

• Diphenoxylate with atropine slows peristalsis by acting on the smooth muscles in the intestine and is used to treat moderate to severe diarrhea.
• Diphenoxylate with atropine adverse effects include tachycardia, dizziness, headache, flushing, nausea and vomiting, dry skin and mucous membranes, and urinary retention, and hypotension and respiratory depression have occurred, particularly with doses greater than ordered.
• Bismuth salts have antibacterial and antiviral activity.
• Bismuth subsalicylate, a commonly used over-the-counter drug, also has antisecretory and possibly anti-inflammatory effects because of its salicylate component.
• Octreotide acetate, a synthetic form of somatostatin, may be effective in diarrhea because it decreases GI secretion and motility
• Polycarbophil and psyllium are occasionally used in diarrhea to adsorb toxins and water, decreasing the fluidity of stools.
• Cholestyramine and colestipol are useful in treating diarrhea due to bile salt accumulation in conditions such as Crohn disease or surgical excision of the ileum.
• Alosetron is a selective 5-HT3 receptor antagonist used for treating females with chronic severe diarrhea-predominant IBS that is unresponsive to other treatments.

Assessment

• Determine the duration, number of stools per day, amount, consistency, color, odor, and presence of abnormal components in each stool.
• Try to identify precipitating factors, accompanying signs and symptoms, and measures used to relieve diarrhea.
• Try to determine the cause.
• Assess for dehydration, hypokalemia, and other fluid and electrolyte disorders in patients with severe or prolonged diarrhea, especially in young children and older adults.

Implementation

• Educate on measures to prevent diarrhea by storing and preparing food properly and avoiding improperly stored or prepared foods.
• Dairy products, cream pies, and other foods may cause diarrhea if not refrigerated.
• Wash hands before handling any foods, after handling raw poultry or meat, and always before eating.
• Emphasize chewing food well, and not overusing laxatives.
• Provide education about prescribed drug therapy.
• Supportive care is necessary regardless of whether antidiarrheal drugs are used.
• Replace fluids and electrolytes (2 to 3 quarts daily) with fluids such as weak tea, water, bouillon, clear soup, and gelatin.
• If the patient cannot tolerate adequate amounts of oral liquids or if diarrhea is severe or prolonged, intravenous fluids may be needed.
• Avoid foods and fluids that may further irritate the GI mucosa (e.g., highly spiced foods or "laxative” foods, such as raw fruits and vegetables).
• Increase the frequency and length of rest periods and decrease activity.
• Exercise and activity stimulate peristalsis.
• Cleanse perianal irritation caused by frequent liquid stools with mild soap and water and then apply an emollient, such as white petrolatum.