Diarrhea: how to treat diarrhea and antidiarrheals

What is Diarrhea?

Diarrhea can be explained as a frequent, often precipitate passage of poorly formed stools. The WHO defines the condition as 3 or more loose or watery stools in a period of 24-hours. Pathologically, it can be explained as a condition where the excess passage of water occurs in the feces.

Diarrhea can be a cause of 

  • Decreased electrolyte and water absorption
  • Increased secretion by the intestinal mucosa
  • Increased luminal osmotic load 
  • Inflammation of mucosa and exudation into the lumen.

The drugs used for such conditions are known as antidiarrheal drugs.

Acute diarrhoeal disease poses a serious risk to elderly patients, and it is one of the leading causes of childhood mortality and morbidity. Traveler’s diarrhea is a frequent health problem that causes an electrolyte imbalance. The therapy prioritizes treating the rootcause, correction of dehydration, and electrolyte imbalance.

Chronic diarrhea, mostly non-infectious, is the fluid loss persisting for longer than a month—the causes include gluten-sensitivity, inherited metabolic disorders, or inflammatory bowel disease.

Diarrhea Medicines (Antidiarrheal Drugs): How do they work?

Diarrhea Medicines
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Rational management for diarrhea treatment depends on investigating the underlying cause and prescribing drugs for specific therapy (if necessary). Since most diarrheas are self-limiting, it is not advisable to take self-medication until necessary.

The majority of diarrhea-causing entero-pathogens are prevented from causing infection, by motility and other protective gut mechanisms. Drugs for therapeutic management can be broadly grouped into:

(a) Treatment of fluid depletion, shock, and acidosis – rehydration is majorly required that can be done orally or I.V. depending on the severity.

(b) Maintenance of nutrition – the patients of diarrhea should not be starved or given lesser food. This is because fasting decreases the brush-border enzymes that reduce salt, water, and nutrient absorption, leading to malnutrition. Simple food like half-strength buffalo milk, boiled potato, rice, chicken soup, banana should be given as soon as the patient can eat.

(c) Drug therapy – these are the drugs used to calm irritated bowel for symptomatic relief.

The severity and nature of diarrhea govern the relative importance of each measure.

Different classes of antidiarrheal drugs

Rehydrating agents

  1. Intravenous rehydration – needed in severe fluid loss (>10% of body weight). Recommended I.V. fluid composition – 5g NaCl, 1g KCl, 4g NaHCO3 in 1L water, or 5% glucose solution. (Dhaka fluid). The volume equal to 10% body weight is infused over 2-4 hours.
  2. Oral rehydration therapy (ORT) – ORT is the widely used treatment in the cases of mild (5-7% of body weight) to moderate (7.5-10% of body weight) fluid loss from the very beginning. Patients are advised to drink ORS at 30-60 minutes intervals.

Drug therapy

  1. Bulking agents (absorbents)– these agents are used for diarrhea in functional bowel disease. Drugs – guar gum or plant fibers (bran, sterculia, isabgol)
  1. Absorbents – absorb toxic substances that cause infective diarrhea. Drug – Methylcellulose, carboxymethyl cellulose, kaolin, pectin, attapulgite
  1. Anti-inflammatory – Locally coat the lining of the GIT to soothe the irritation that may stimulate the reflex. Drugs – bismuth subsalicylate (anti-inflammatory – subsalicylate, anti-bacterial – bismuth)
  1. Anticholinergics – reduce intestinal movement and are effective against both diarrhea and accompanying cramping. Drugs – metoclopramide, neostigmine, atropine
  1. Opioids – Opioids have agonist actions on the intestinal opioid receptors, which when activated cause constipation. Drugs – loperamide, opium tincture, difenoxin, diphenoxylate
  1. Probiotics – used as dietary supplementation for bacterial replacement. Drug- Lactobacillus acidophilus

Antidiarrheal drugs: Indications in which they are used 

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  • Acute (2-3 weeks) and chronic diarrhea (>3 weeks)
  • Reduction of fecal discharges from ileostomies
  • Management and treatment of Traveler’s diarrhea
  • Poisoning 
  • Drug allergy
  • GI obstruction 
  • Acute abdominal conditions
  • Ulcerative colitis 

Antidiarrheal drugsSide effects

  • Constipation
  • Nausea, vomiting
  • Abdominal distention and discomfort 
  • Toxic megacolon

Antidiarrheal drugsContraindications 

  • Loperamide contraindicated in children below 4 years of age
  • Loperamide contraindicated in infective diarrhea, ulcerative colitis, irritable bowel syndrome
  • All drugs are contraindicated in bloody diarrhea, fever, or systemic toxicity
  • Discontinue the therapy if the condition does not improve
  • Bile tract disease
  • Crohn’s disease


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