( Anti-diarrheals.... )
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|Mode Of Action
Antidiarrheal—Exact mechanism has not been determined. Bismuth subsalicylate may exert its antidiarrheal action not only by stimulating absorption of fluid and electrolytes across the intestinal wall (antisecretory action) but also, when hydrolyzed to salicylic acid, by inhibiting synthesis of a prostaglandin responsible for intestinal inflammation and hypermotility. In addition, bismuth subsalicylate binds toxins produced by Escherichia coli . Both bismuth subsalicylate and the intestinal reaction products, bismuth oxychloride and bismuth hydroxide, are believed to have bactericidal action.
Antacid—Bismuth has weak antacid properties.
Following oral administration, absorption of the salicylate component from the small intestine is generally rapid and complete (>90%). In contrast to the salicylate, the amount of bismuth absorbed is negligible(<0.005%).
Protein binding: Salicylate—High (to albumin).
Based on in vitro dissociation data and in vivo animal data, bismuth subsalicylate is believed to be largely hydrolyzed in the stomach to bismuth oxychloride and salicylic acid. In the small intestine, nondissociated bismuth subsalicylate reacts with other anions (bicarbonate and phosphate) to form insoluble bismuth salts. In the colon, nondissociated bismuth subsalicylate and other bismuth salts react with hydrogen sulfide to produce bismuth sulfide, a highly insoluble black salt responsible for the darkening of the stools.
Bismuth—Fecal (>99% of the bismuth present in an oral dose); renal.
Salicylate—Renal (primarily excreted as free salicylic acid and conjugated metabolites).
• Bismuth subsalicylate is indicated for the symptomatic treatment of nonspecific diarrhea.
• Bismuth subsalicylate is indicated for the symptomatic relief of upset stomach, including heartburn, acid indigestion, and nausea.
• Bismuth subsalicylate is used for the prevention of secretory diarrhea produced by enterotoxigenic Escherichia coli (traveler's diarrhea) and viral infections.
• Bismuth subsalicylate is used, in combination with oral antibiotic therapy, in the treatment of Helicobacter pylori –associated gastritis and duodenal ulcer.
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance, risk-benefit should be considered when the following medical problems exist:
Bleeding ulcers or Hemorrhagic states; Dehydration; Dysentery, acute, characterized by bloody stools and elevated temperature; Gout; Hemophilia; Renal function impairment; Sensitivity to bismuth subsalicylate.
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:
Those indicating need for medical attention:
—reported with higher-than-recommended doses and/or chronic dosing; may also be signs of overdose:
Bismuth encephalopathy (anxiety; confusion; difficulty in speaking or slurred speech; severe and/or continuing headache; mental depression; muscle spasms, especially of face, neck, and back; muscle weakness; trembling; uncontrolled body movements)
salicylism, symptoms of (any loss of hearing; confusion; severe or continuing diarrhea; dizziness or lightheadedness; severe drowsiness; fast or deep breathing; severe or continuing headache; increased sweating; increased thirst; severe or continuing nausea or vomiting; continuing ringing or buzzing in ears; severe or continuing stomach pain; uncontrollable flapping movements of the hands, especially in elderly patients; vision problems)
Those not indicating need for medical attention:
Incidence more frequent
Discoloration produced by bismuth (darkening of tongue or grayish black stools).
Although significant interactions are unlikely with usual doses of bismuth subsalicylate in the treatment of diarrhea and for occasional relief of gastric distress, the higher doses and the longer therapy used in the prophylaxis of traveler's diarrhea increase the potential for significant drug interactions.
Combinations containing any of the following medications, depending on the amount present, may also interact with this medication.
» Anticoagulants, coumarin- or indandione-derivative or
» Heparin or
» Thrombolytic agents, such as:
Alteplase (tissue-type plasminogen activator, recombinant)
Urokinase (increased risk of bleeding may occur when these medications are used concurrently with salicylates)
» Antidiabetic agents, oral or
Insulin (large doses of salicylate may enhance the hypoglycemic effect of these medications; dosage adjustment may be necessary)
» Probenecid or
» Sulfinpyrazone (concurrent use of salicylates is not recommended when these medications are used to treat hyperuricemia or gout because uricosuric effects of these medications may be decreased by doses of salicylates that produce serum salicylate concentrations above 50 mcg per mL)
(probenecid may decrease renal clearance and increase plasma concentrations and toxicity of salicylates)
» Salicylates, other (ingestion of large repeated doses of bismuth subsalicylate, as for traveler's diarrhea, may produce substantial plasma salicylate concentrations thus increasing the risk of salicylate toxicity during concurrent use with other salicylates)
» Tetracyclines, oral (calcium carbonate contained in the tablet dosage form may decrease gastrointestinal absorption and bioavailability of tetracyclines; patients should be advised not to take bismuth subsalicylate tablets within 1 to 3 hours of oral tetracyclines.
Patients sensitive to salicylates including methyl salicylate(oil of wintergreen), or to other nonsteroidal anti-inflammatory drugs (NSAIDs), may be sensitive to bismuth subsalicylate also.
In infants and children up to 3 years of age with diarrhea, caution is recommended because of the risk of fluid and electrolyte loss; these patients should be referred to a physician.
Pediatric patients, especially those with fever and dehydration, may be more susceptible to the toxic effects of salicylates. Bismuth is more likely to cause impaction in children.
Also, elderly patients are more likely to have age-related renal function impairment, which may increase the risk of salicylate toxicity. Dosage reduction may be required to prevent accumulation of the medication.
|Usage in Pregnancy & Lactation
The occasional use of bismuth subsalicylate during pregnancy is not likely to result in adverse effects on the fetus or newborn; however, based on what is known about salicylates, the following information should be considered with higher doses and longer therapy.
Fertility—Salicylates have caused increased numbers of fetal resorptions in animal studies.
Pregnancy—First trimester: Salicylates readily cross the placenta. Studies in animals have shown that salicylates cause birth defects including fissure of the spine and skull; facial clefts; eye defects; and malformations of the central nervous system (CNS), viscera, and skeleton (especially the vertebrae and ribs). It has been reported that salicylate use during pregnancy may increase the risk of birth defects in humans.
Third trimester: Chronic, high-dose salicylate therapy may result in prolonged gestation, increased risk of postmaturity syndrome (fetal damage or death due to decreased placental function if pregnancy is greatly prolonged), and increased risk of maternal antenatal hemorrhage. Also, ingestion of salicylates during the last 2 weeks of pregnancy may increase the risk of fetal or neonatal hemorrhage. The possibility that regular use late in pregnancy may result in constriction or premature closure of the fetal ductus arteriosus, possibly leading to persistent pulmonary hypertension and heart failure in the neonate, must also be considered.
Labor and delivery—Chronic, high-dose salicylate therapy late in pregnancy may result in prolonged labor, complicated deliveries, and increased risk of maternal or fetal hemorrhage.
Problems in humans have not been documented. However, salicylate is distributed into breast milk; with chronic, high-dose use, intake by the infant may be high enough to cause adverse effects.
|Dosage & Administration
Susp: 88 mg/5ml, Tabs: 265 mg,
Adult Dosage (>12 years): Oral: 2 X teapoons/5ml as recommended, donot take more than 16 tablespoons in a day.
Children up to 3 years of age: 1/2 teaspoon as recommended, donot exceed more than 352mg in a day.
Children 3 to 6 years of age: 1 teaspoon as recommended, donot exceed more than 704mg a day.
Children 6 to 12 years of age: 1-1½ teaspoon as recommended, donot exceed more than 1.4 grams in a day.