Antacids
Summary

drug class: Antacids

Note: see "Aluminum Hydroxide" for information on aluminum-based antacids such as Di-Gel, Maalox, Mylanta, Riopan, Rolaids, etc.

used to treat: heartburn, reflux esophagitis, gastritis, peptic ulcer

mechanism: Antacids are used to reduce stomach acidity as the presumed cause of symptoms such as heartburn, gastritis and ulcers. Some physicians also believe that calcium-containing antacids are an effective source of supplemental calcium in the treatment and prevention of osteoporosis; even though much evidence indicates that a low-acid environment inhibits proper calcium absorption.

overview of interactions:
• nutrient affected by drug: Folic Acid

• nutrients affected by drug: Copper and Phosphate and Phosphate

• nutrient affected by drug: Potassium

• adverse drug interactions: Antacids reduce absorption of a large number of pharmaceuticals.



Interactions

adverse drug interactions: Antacids reduce absorption of a large number of pharmaceuticals.
(Gugler R, Allgayer H. Clin Pharmacokinet 1990 Mar;18(3):210-219.)

nutrient affected by drug: Folic Acid

• mechanism: Antacids, with or without pancreatic enzymes, have been reported to interfere with folic acid absorption. Malabsorption with prolonged intake of antacids may cause low or deficient plasma and erythrocyte levels of folacin.
(Roe DA. 1989, 85-86; Russell, RM, et al. Dig Dis Sci 1980;25(5):369-373.)

• nutritional support: Individuals who take antacids for an extended period of time would benefit from folate supplementation to protect against depletion of folate. This could be in the form of a folate supplement or as part of a multivitamin/mineral formula.

nutrients affected by drug: Copper and Phosphate

• mechanism: Antacids may reduce absorption of copper and phosphate. Antacids may induce a copper deficiency by precipitating dietary copper due to the drug-induced alkaline pH in the intestines.
(Roe DA. 1989, 85-86.)

• nutritional support: Individuals who take antacids for an extended period of time would benefit from copper supplementation to protect against depletion of folate. This could be in the form of a multivitamin/mineral formula. Depletion of phosphate is usually not a concern.

nutrient affected by drug: Potassium

• mechanism: Antacids may cause low blood levels of potassium when used excessively.
(Lotz M, et al. N Eng J Med. 1968; 278:409.)

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Do not rely solely on the information in this article.

The information presented in Interactions is for informational and educational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, case reports, and/or traditional usage with sources as cited in each topic. The results reported may not necessarily occur in all individuals and different individuals with the same medical conditions with the same symptoms will often require differing treatments. For many of the conditions discussed, treatment with conventional medical therapies, including prescription drugs or over-the-counter medications, is also available. Consult your physician, an appropriately trained healthcare practitioner, and/or pharmacist for any health concern or medical problem before using any herbal products or nutritional supplements or before making any changes in prescribed medications and/or before attempting to independently treat a medical condition using supplements, herbs, remedies, or other forms of self-care.


References

Russell RM, Dutta SK, Oaks EV, Rosenberg IH, Giovetti AC. Impairment of folic acid absorption by oral pancreatic extracts. Dig Dis Sci 1980;25(5):369-373.
Abstract: Higher serum folate levels were found among newly diagnosed, untreated patients with pancreatic insufficiency than among treated patients despite greater fat malabsorption in the former group. In vivo folate absorption tests using Tritium-labeled pteroylmonoglutamatic acid showed folate absorption to be enhanced in pancreatic insufficiency patients as compared to control subjects (P less than 0.01). Moreover, pancreatic extract significantly inhibited folate absorption in both normal subjects (P less than 0.05) and pancreatic insufficient patients (P less than 0.001). In vitro testing showed pancreatic extract to form insoluble complexes with folate. Such complex formation may diminish absorption of dietary folate and lead to folate deficiency. Since both pancreatic extract and bicarbonate are used in the treatment of pancreatic insufficiency and both are known to impair folate absorption, folate status should be monitored in patients being treated for pancreatic insufficiency; supplementation may be indicated.

Werbach, MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 206. (Review)

Gugler R, Allgayer H. Effects of antacids on the clinical pharmacokinetics of drugs. An update. Clin Pharmacokinet 1990 Mar;18(3):210-219.
Abstract: Since a previous review by Hurwitz was published in 1977 a large number of reports on drug interactions with antacids have appeared, few of which are of clinical relevance. Tetracyclines form insoluble complex molecules by metal ion chelation with various antacids; tetracycline absorption may be decreased by more than 90% by this interaction. Of the new class of quinolone antibiotics, the absorption of ciprofloxacin and ofloxacin is reduced by 50 to 90% in the presence of aluminium- and magnesium hydroxide-containing antacids. In contrast to early work showing inhibition of the absorption of beta-adrenergic blocking drugs by antacids, subsequent studies did not confirm a reduction in the bioavailability of either atenolol or propranolol during antacid treatment; indeed, they showed an increase in the plasma concentrations of metoprolol when the drug was coadministered with an antacid. The bioavailability of captopril was significantly reduced in the presence of an antacid, and lower plasma concentrations of this angiotensin-converting enzyme inhibitor were accompanied by a reduction of its effect on the systolic blood pressure of the patients. The absorption of the cardiac glycosides digoxin and digitoxin is not inhibited by antacids to a significant degree, although earlier studies had shown a positive effect when the dissolution of the glycoside preparations was relatively poor. Antacids reduce the bioavailability of the H2-receptor antagonists cimetidine and ranitidine only when high antacid doses are used and when the drugs are administered simultaneously. The bioavailability of famotidine was not significantly altered by a potent antacid preparation, although a trend towards reduced absorption was observed. Iron absorption is significantly decreased in the presence of sodium bicarbonate and calcium carbonate, but is nearly complete when coadministered with aluminium-magnesium hydroxide. Nonsteroidal anti-inflammatory drugs such as naproxen, tenoxicam, ketoprofen, ibuprofen and piroxicam are not affected in their absorption by antacid treatment. Theophylline bioavailability is unchanged when the drug is given together with antacids, although its rate of absorption may be altered, leading to a reduction or an increase in the time of the occurrence of peak plasma drug concentrations.

Lotz M, Zisman E, Bartter FC. Evidence for a phosphorus-depletion syndrome in man. N Eng J Med. 1968; 278:409.

Roe DA. Diet and Drug Interactions. New York: Van Nostrand Reinhold, 1989.