bismuth subsalicylate (Kaopectate, Pepto Bismol, Maalox Total Relief, Kaopectate Extra Strength, Pepto-Bismol Maximum Strength)
Classes: Antidiarrheals; H pylori Agents
Dosing and uses of Kaopectate, Pepto Bismol (bismuth subsalicylate)
Adult dosage forms and strengths
tablet, chewable
- 262mg
- 525mg
caplet
- 262mg
oral suspension
- 262mg/15mL
- 525mg/15mL
Diarrhea, Gas, Upset Stomach, Indigestion, Heartburn, Nausea
2 tablets (262 mg/tab) or 30 mL (regular strength) PO q½-1hr PRN; maximum daily dose: 8 regular-strength doses or 4 extra-strength doses
Traveler's Diarrhea
Prophylaxis
2 tablets (262 mg/tab) q6hr for up to 3 weeks
Helicobacter Pylori
525 mg (2 regular-strength tablets or 1 extra-strength tablet) + 250 mg metronidazole + 500 mg tetracycline PO q6hr for 14 days, plus an H2 antagonist (Helidac Therapy pack)
Dosing Modifications
Renal impairment: Overdose may cause nephrotoxicity
Administration
Drink plenty of clear fluids to prevent dehydration caused by diarrhea
Do not use for >2 days
Helidac Therapy pack: Bismuth subsalicylate tablets should be chewed and swallowed; if a dose is missed, double doses should not be taken
Pediatric dosage forms and strengths
tablet, chewable
- 262mg
oral suspension
- 262mg/15mL
- 525mg/15mL
Diarrhea, Gas, Upset Stomach, Indigestion, Heartburn, Nausea
<3 years: Safety and efficacy not established
3-6 years: 1/3 tablet or 5 mL (regular strength) or 2.5 mL (extra strength) PO q½-1hr PRn
6-9 years: 2/3 tablet or 10 mL (regular strength) or 5 mL (extra strength) PO q½-1hr PRn
9-12 years: 1 tablet or 15 mL (regular strength) or 7.5 mL (extra strength) PO q½-1hr PRn
>12 years: 2 tablets or 30 mL (regular strength) or 15 mL (extra strength) PO q½-1hr PRN; maximum daily dose: 8 regular-strength doses or 4 extra-strength doses
Chronic Infantile Diarrhea
<2 years: 2.5 mL (regular strength) q4hr
2-4 years: 5 mL (regular strength) q4hr
4-6 years: 10 mL (regular strength) q4hr
Kaopectate, Pepto Bismol (bismuth subsalicylate) adverse (side) effects
>10%
Nausea (12%)
1-10%
Diarrhea (7%)
Abdominal pain (7%)
Melena (3%)
Upper respiratory tract infection (2%)
Constipation (2%)
Anorexia (2%)
Vomiting (2%)
Asthenia (2%)
Discolored tongue (2%)
Headache (2%)
Dyspepsia (2%)
Dizziness (2%)
Stool abnormality (1%)
Duodenal ulcer (1%)
Sinusitis (1%)
Taste perversion (1%)
Flatulence (1%)
GI hemorrhage (1%)
Pain (1%)
Insomnia (1%)
Anal discomfort (1%)
Paresthesia (1%)
Frequency not defined
Anxiety
Confusion
Depression
Tinnitus
Weakness
Gray-black stooL
Impaction
Muscle spasm
Neurotoxicity (rare)
Warnings
Contraindications
Hypersensitivity to bismuth, aspirin, other salicylates
Infectious diarrhea, high fever, von Willebrand disease, hemorrhage, ulcer or GI bleeding with black or bloody stool, hemophilia
In pediatric patients, chicken pox or influenza (risk of Reye syndrome); changes in behavior with nausea and vomiting may be early sign of Reye syndrome
Cautions
May cause black tongue and/or black stooL
May interfere with GI radiographic tests
Pregnancy and lactation
Pregnancy category: C; D in 3rd trimester
Lactation: Salicylates enter breast milk; use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Kaopectate, Pepto Bismol (bismuth subsalicylate)
Mechanism of action
Antimicrobial anti-inflammatory action (bismuth); antisecretory effect (salicylate)
Absorption
Bioavailability: Bismuth, <1%; salicylate, 80%
Peak plasma time: Bismuth, 1.8-5 hr
Onset: 4 hr
Distribution
Protein bound: Bismuth, 90%; salicylate, >90%
Vd: Bismuth, 170 mL/kg
Metabolism
Stomach: Bismuth subsalicylate is hydrolyzed in stomach to form slightly soluble bismuth oxychloride (BiOCl) and salicylic acid
Small intestine: Unchanged bismuth subsalicylate passes into duodenum and reacts with other anions (eg, bicarbonate and phosphate) to form bismuth subcarbonate and bismuth phosphate salts
Colon: BiOCl, bismuth subcarbonate, bismuth phosphate, and undissociated bismuth subsalicylate react with hydrogen sulfide (produced by colonic anaerobes) to form black bismuth sulfide, which is responsible for harmless darkening of stool and/or tongue
Liver: Salicylate is extensively metabolized in liver
Metabolites: Salicylate (active); BiOCl, bismuth subcarbonate, and bismuth phosphate (activity unknown)
Elimination
Half-life: Bismuth, 21-72 days; salicylate, 2.5 hr
Excretion: Bismuth, feces (99%) and urine (0.003%); salicylate, urine (95%)
Clearance: Bismuth, 50 mL/min
