Introduction
Kaopectate is an over-the-counter antidiarrheal medication that has undergone significant formulation changes throughout its history. Originally containing kaolin and pectin, modern formulations in the United States now typically contain bismuth subsalicylate as the active ingredient. It is widely used for the symptomatic relief of acute diarrhea and associated gastrointestinal discomfort.
Mechanism of Action
Bismuth subsalicylate, the current active ingredient in Kaopectate, exerts its antidiarrheal effects through multiple mechanisms:
- Adsorptive properties: Binds to toxins, bacteria, and irritants in the gastrointestinal tract
- Anti-inflammatory effects: Salicylate component provides local anti-inflammatory action in the gut
- Antimicrobial activity: Demonstrates bactericidal effects against various enteric pathogens including E. coli, Vibrio cholerae, and Campylobacter jejuni
- Reduction of fluid secretion: Decreases intestinal fluid secretion and normalizes intestinal motility
Indications
- Symptomatic treatment of acute, nonspecific diarrhea
- Relief of abdominal cramping and discomfort associated with diarrhea
- Adjuvant therapy for traveler's diarrhea (often in combination with antibiotics for bacterial causes)
- Management of indigestion and upset stomach (off-label use)
Dosage and Administration
Adults and children ≥12 years:- 524 mg (2 tablets or 30 mL liquid) every 30-60 minutes as needed
- Maximum daily dose: 4.2 g (8 doses)
- 262 mg (1 tablet or 15 mL) every 30-60 minutes as needed
- Maximum daily dose: 2.1 g (8 doses)
- 175 mg (10 mL) every 30-60 minutes as needed
- Maximum daily dose: 1.05 g (6 doses)
- 87 mg (5 mL) every 30-60 minutes as needed
- Maximum daily dose: 525 mg (6 doses)
- Renal impairment: Use with caution; consider alternative agents in severe impairment
- Hepatic impairment: No specific dosage adjustment recommended
- Elderly: No dosage adjustment typically required
Pharmacokinetics
Absorption: Minimal systemic absorption of bismuth; salicylate component undergoes partial absorption Distribution: Primarily local action in gastrointestinal tract; absorbed salicylate distributes throughout body fluids and tissues Metabolism: Hepatic metabolism of absorbed salicylate via conjugation with glycine and glucuronic acid Elimination: Renal elimination of absorbed salicylate; unabsorbed bismuth is excreted in feces Half-life: Salicylate half-life is 2-3 hours at low doses; bismuth has extremely long half-life (21-72 days) due to poor absorptionContraindications
- Hypersensitivity to bismuth subsalicylate or any component of the formulation
- Children and teenagers with viral infections (due to risk of Reye's syndrome)
- Patients with history of aspirin-sensitive asthma
- Hemophilia or other bleeding disorders
- Severe renal impairment (CrCl <30 mL/min)
- Concomitant use with other salicylate-containing products
Warnings and Precautions
- Reye's syndrome risk: Avoid use in children and teenagers with chickenpox or flu-like symptoms
- Salicylate toxicity: Potential for salicylate accumulation, particularly in elderly or those with renal impairment
- Black stools: Inform patients that bismuth may cause harmless darkening of stools and tongue
- Electrolyte imbalance: Monitor for signs of dehydration in prolonged diarrhea
- Tinnitus: May indicate salicylate toxicity; discontinue use if occurs
- Pregnancy: Category C; use only if clearly needed (salicylate component concerns)
- Lactation: Salicylates excreted in breast milk; use with caution
Drug Interactions
- Anticoagulants: Increased risk of bleeding with warfarin and other anticoagulants
- Hypoglycemic agents: Salicylates may enhance effects of insulin and oral hypoglycemics
- Uricosuric agents: Salicylates may decrease effectiveness of probenecid and sulfinpyrazone
- NSAIDs: Increased risk of GI irritation and salicylate toxicity
- ACE inhibitors: Salicylates may reduce antihypertensive effects
- Methotrexate: Increased methotrexate toxicity possible
- Val