Chemistry - Bismuth subsalicylate occurs as white or nearly white, tasteless, odorless powder and contains about 58% bismuth. It is insoluble in water, glycerin and alcohol. It may also be known as bismuth salicylate , or bismuth oxysalicylate.
Storage/Stability/Compatibility - Bismuth subsalicylate should be stored protected from light. It is incompatible with mineral acids and iron salts. When exposed to alkali bicarbonates, bismuth subsalicylate decomposes with effervescence.
Pharmacology - Bismuth subsalicylate is thought to posses protectant, anti-endotoxic and weak antibacterial properties. It is believed that the parent compound is cleaved in the small intestine into bismuth carbonate and salicylate. The protectant, anti-endotoxic and weak antibacterial properties are thought to be as a result of the bismuth. The salicylate component has antiprostaglandin activity which may contribute to its effectiveness and reduce symptoms associated with secretory diarrheas.
Uses/Indications - In veterinary medicine, bismuth subsalicylate products are used to treat diarrhea. The drug is also used in humans for other GI symptoms (indigestion, cramps, gas pains) and in the treatment and prophylaxis of traveler’s diarrhea.
Pharmacokinetics - No specific veterinary information was located. In humans, the amount of bismuth absorbed is negligible while the salicylate component is rapidly and completely absorbed. Salicylates are highly bound to plasma proteins and are metabolized in the liver to salicylic acid. Salicylic acid, conjugated salicylate metabolites and any absorbed bismuth are all excreted renally.
Contraindications/Precautions - Salicylate absorption may occur; use with caution in patients with preexisting bleeding disorders. Because of the potential for adverse effects caused by the salicylate component, this drug should be used cautiously, if at all, in cats.
Adverse Effects/Warnings - Antidiarrheal products are not a substitute for adequate fluid and electrolyte therapy when required. May change stool color to a gray-black or greenish-black; do not confuse with melena. In human infants and debilitated individuals, use of this product may cause impactions to occur. As bismuth is radiopaque, it may interfere with GI tract radiologic examinations.
Overdosage - No specific information located, but theoretically may cause salicylism. See the Aspirin monograph for more information.
Drug Interactions - Bismuth containing products can decrease the absorption or orally administered tetracycline products. If both agents are to be used, separate drugs by at least 2 hours and administer tetracycline first. Because bismuth subsalicylate contains salicylate, concomitant administration with aspirin may increase salicylate serum levels; monitor appropriately.
Laboratory Test Interference - At high doses, salicylates may cause false-positive results for urinary glucose if using the cupric sulfate method (Clinitest®, Benedict’s solution) and false-negative results if using the glucose oxidase method (Clinistix® or Tes-Tape®). Urinary ketones measured by the ferric chloride method (Gerhardt) may be affected if salicylates are in the urine (reddish-color produced). 5-HIAA determinations by the fluoremetric method may be interfered by salicylates in the urine. Falsely elevated VMA (vanillylmandelic acid) may be seen with most methods used if salicylates are in the urine. Falsely lowered VMA levels may be seen if using the Pisano method. Urinary excretion of xylose may be decreased if salicylates are given concurrently. Falsely elevated serum uric acid values may be measured if using colorimetric methods.
a) For foals: 0.5 ml per kg PO q4-6h, response usually within 48 hours. After diarrhea resolves, taper off drug. (Wilson 1987)
b) For foals or adults: 1 ounce per 8 kg of body weight PO tid-qid (Clark and Becht 1987)
c) For foals: 3 - 4 oz. PO q6-8h (Martens and Scrutchfield 1982)
d) For foals: 60 ml bid-qid for two days (Label Directions - Corrective Mixture®; (Beecham))
Monitoring Parameters -
1) Clinical efficacy
2) Fluid & electrolyte status in severe diarrhea
Client Information - Shake well before using. If diarrhea persists, contact veterinarian. May change stool color to a gray-black or greenish-black; contact veterinarian if stool becomes “tarry” black. Refrigeration of the suspension may improve palatability. Do not mix with milk before administering.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Corrective Suspension® ; (Phoenix): Bismuth subsalicylate 17.5 mg/ml. Available in gallons.; (OTC) Labeled for use in cattle, horses, calves, folas, dogs and cats.
Bismuth Subsalicylate Suspension 262 mg/15 ml & 524 mg/15 ml in 120 ml, 240 ml, 360 ml bottles.; Pepto-Bismol® (Procter & Gamble); Bismatrol Extra Strength® (Major); Pepto-Bismol Extra Strength® (Procter & Gamble); Generic (OTC)
Bismuth Subsalicylate Tablets & Caplets (Chewable) 262 mg;Pepto-Bismol® (Procter & Gamble); (OTC);Bismatrol® (Major); (OTC)
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