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?
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
- 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.
- 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.
- Bulking agents (absorbents)– these agents are used for diarrhea in functional bowel disease. Drugs – guar gum or plant fibers (bran, sterculia, isabgol)
- Absorbents – absorb toxic substances that cause infective diarrhea. Drug – Methylcellulose, carboxymethyl cellulose, kaolin, pectin, attapulgite
- 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)
- Anticholinergics – reduce intestinal movement and are effective against both diarrhea and accompanying cramping. Drugs – metoclopramide, neostigmine, atropine
- Opioids – Opioids have agonist actions on the intestinal opioid receptors, which when activated cause constipation. Drugs – loperamide, opium tincture, difenoxin, diphenoxylate
- Probiotics – used as dietary supplementation for bacterial replacement. Drug- Lactobacillus acidophilus
Antidiarrheal drugs: Indications in which they are used
- Acute (2-3 weeks) and chronic diarrhea (>3 weeks)
- Reduction of fecal discharges from ileostomies
- Management and treatment of Traveler’s diarrhea
- Drug allergy
- GI obstruction
- Acute abdominal conditions
- Ulcerative colitis
Antidiarrheal drugs– Side effects
- Nausea, vomiting
- Abdominal distention and discomfort
- Toxic megacolon
Antidiarrheal drugs– Contraindications
- 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