Antacid Explained

An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion, or an upset stomach.[1] Some antacids have been used in the treatment of constipation and diarrhea.[2] Marketed antacids contain salts of aluminum, calcium, magnesium, or sodium. Some preparations contain a combination of two salts, such as magnesium carbonate and aluminum hydroxide (e.g., hydrotalcite).[3]

Medical uses

Antacids are available over the counter and are taken by mouth to quickly relieve occasional heartburn, the major symptom of gastroesophageal reflux disease and indigestion. Treatment with antacids alone is symptomatic and only justified for minor symptoms.[4] Alternative uses for antacids include constipation, diarrhea, hyperphosphatemia, and urinary alkalization. Some antacids are also used as an adjunct to pancreatic enzyme replacement therapy in the treatment of pancreatic insufficiency.[5]

Non-particulate antacids (sodium citrate) increase gastric pH with little or no effect on gastric volume, and therefore may see some limited use in pre-operative procedures. Sodium citrate should be given within 1 hour of surgery to be the most effective.[6]

Side effects

Conventional effervescent tablets contain a significant amount of sodium and are associated with increased odds of adverse cardiovascular events according to a 2013 study.[7] Alternative sodium-free formulations containing magnesium salts may cause diarrhea, whereas those containing calcium or aluminum may cause constipation.[8] Long-term use of antacids containing aluminum may increase the risk of developing osteoporosis.[9] In vitro studies have found a potential for acid rebound to occur due to antacid overuse, however the significance of this finding has been called into question.[10] [11]

Properties of antacids

When an excess amount of acid is produced in the stomach, the natural mucous barrier that protects the lining of the stomach can degrade, leading to pain and irritation. There is also potential for the development of acid reflux, which can cause pain and damage to the esophagus. Antacids contain alkaline ions that chemically neutralize stomach gastric acid, reducing damage to the stomach lining and esophagus, and relieving pain. Some antacids also inhibit pepsin, an enzyme that can damage the esophagus in acid reflux.[2] [12]

Antacids do not directly inhibit acid secretion, and thus are distinct from acid-reducing drugs like H2-receptor antagonists or proton pump inhibitors. Antacids do not kill the bacteria Helicobacter pylori, which causes most ulcers.

Interactions

Antacids are known to interact with several oral medications, including fluoroquinolone and tetracycline antibiotics, iron, itraconazole, and prednisone.[13] Metal chelation is responsible for some of these interactions (e.g. fluoroquinolones, tetracyclines), leading to decreased absorption of the chelated drug. Some interactions may be due to the pH increase observed in the stomach following antacid ingestion, leading to increased absorption of weak acids, and decreased absorption of weak bases. Antacids also cause an increase in pH of the urine (alkalization), which may cause increased blood concentrations of weak bases, and increased excretion of weak acids.[14]

A proposed method to mitigate the effects of stomach acidity and chelation on drug absorption is to space out the administration of antacids with interacting medications by at least two hours,[15] however this method has not been well studied for drugs affected by urine alkalization.

There are concerns regarding interactions between delayed-release tablets and antacids, as antacids may increase the stomach pH to a point at which the coating of the delayed-release tablet will dissolve, leading to degradation of the drug if it is pH sensitive.

Formulations

Antacids may be formulated with other active ingredients such as simethicone to control gas, or alginic acid to act as a physical barrier to acid.[16]

Liquids

Several liquid antacid preparations are marketed. Common liquid preparations include milk of magnesia and magnesium/aluminum combinations. A potential advantage of using a liquid preparation over a tablet is that liquids may provide quicker relief, however this may coincide with a shorter duration of action.[17]

Tablets

Chewable tablets

Chewable tablets are one of the most common forms of antacids, most frequently made from carbonate or hydroxide salts, and are readily available over the counter. Upon reaching the stomach, the powdered antacid salts bind to hydronium (H+) ions, producing chloride salts, carbon dioxide, and water. This process reduces the concentration of H+ ions in the stomach, raising the pH and neutralizing the acid. Common carbonate salts available in tablet form include those of calcium, magnesium, aluminum, and sodium.

Some common American brands are Tums, Gaviscon chewable tablets, and Maalox chewable tablets.[18]

Effervescent tablets

Effervescent tablets are tablets which are designed to dissolve in water, and then release carbon dioxide.[19] [20] [21] Common ingredients include citric acid and sodium bicarbonate, which react when in contact with water to produce carbon dioxide. Effervescent antacids may also contain aspirin,[22] sodium carbonate, or tartaric acid.[23] Those containing aspirin may cause further gastric irritation and ulceration due to aspirin's effects on the mucous membrane of the stomach.[24]

Brand names

Some brands include Alka-Seltzer, Gaviscon, Tums, Gelusil and Eno.[25] [26] [27]

Notes and References

  1. Book: Internal Clinical Guidelines Team. (UK). Dyspepsia and Gastro-Oesophageal Reflux Disease: Investigation and Management of Dyspepsia, Symptoms Suggestive of Gastro-Oesophageal Reflux Disease, or Both. 2014. National Institute for Health and Care Excellence (UK). National Institute for Health and Care Excellence: Clinical Guidelines. London. 25340236.
  2. Book: Salisbury BH, Terrell JM . Antacids . StatPearls . 2020 . 30252305 . http://www.ncbi.nlm.nih.gov/books/NBK526049/ . 24 November 2020 . StatPearls Publishing . live . Treasure Island (FL) . https://web.archive.org/web/20211105005803/https://www.ncbi.nlm.nih.gov/books/NBK526049/ . 5 November 2021 .
  3. Web site: Aluminum hydroxide and magnesium carbonate Uses, Side Effects & Warnings. 24 November 2020. Drugs.com. 20 May 2021. https://web.archive.org/web/20210520014232/https://www.drugs.com/mtm/aluminum-hydroxide-and-magnesium-carbonate.html. live.
  4. Web site: U.S. Department of Health & Human Services. Agency for Healthcare Research and Quality . 23 September 2011 . Consumer Summary – Treatment Options for GERD or Acid Reflux Disease: A Review of the Research for Adults . https://web.archive.org/web/20141011121858/http://effectivehealthcare.ahrq.gov/index.cfm/search-for-guides-reviews-and-reports/?productid=756&pageaction=displayproduct . 11 October 2014 .
  5. Graham DY . Pancreatic enzyme replacement: the effect of antacids or cimetidine . Digestive Diseases and Sciences . 27 . 6 . 485–490 . June 1982 . 6282548 . 10.1007/BF01296725 . 10640940 .
  6. Apfelbaum JL, Agarkar M, Connis RT, Coté CJ, Nickinovich DJ, Warner MA . American Society of Anesthesiologists Committee on Standards and Practice Parameters . Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration: Application to Healthy Patients Undergoing Elective Procedures: An Updated Report by the American Society of Anesthesiologists Task Force on Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration . Anesthesiology . 126 . 3 . 376–393 . March 2017 . 28045707 . 10.1097/ALN.0000000000001452 .
  7. George J, Majeed W, Mackenzie IS, Macdonald TM, Wei L . Association between cardiovascular events and sodium-containing effervescent, dispersible, and soluble drugs: nested case-control study . BMJ . 347 . f6954 . November 2013 . 24284017 . 3898660 . 10.1136/bmj.f6954 . free .
  8. Garg V, Narang P, Taneja R . Antacids revisited: review on contemporary facts and relevance for self-management . The Journal of International Medical Research . 50 . 3 . 3000605221086457 . March 2022 . 35343261 . 8966100 . 10.1177/03000605221086457 .
  9. Web site: U.S. Department of Health and Human Services, National Institutes of Health, U.S. National Library of Medicine . 7 November 2014 . Taking Antacids . Medline Plus . https://web.archive.org/web/20160705125204/https://www.nlm.nih.gov/medlineplus/ency/patientinstructions/000198.htm . 5 July 2016 .
  10. Texter EC . A critical look at the clinical use of antacids in acid-peptic disease and gastric acid rebound . The American Journal of Gastroenterology . 84 . 2 . 97–108 . February 1989 . 2644821 .
  11. Hade JE, Spiro HM . Calcium and acid rebound: a reappraisal . Journal of Clinical Gastroenterology . 15 . 1 . 37–44 . July 1992 . 1500660 . 10.1097/00004836-199207000-00010 . 10897187 .
  12. Bardhan KD, Strugala V, Dettmar PW . Reflux revisited: advancing the role of pepsin . International Journal of Otolaryngology . 2012 . 646901 . 2012 . 22242022 . 3216344 . 10.1155/2012/646901 . free .
  13. Ogawa R, Echizen H . Clinically significant drug interactions with antacids: an update . Drugs . 71 . 14 . 1839–1864 . October 2011 . 21942976 . 10.2165/11593990-000000000-00000 . 36875514 .
  14. Patel D, Bertz R, Ren S, Boulton DW, Någård M . A Systematic Review of Gastric Acid-Reducing Agent-Mediated Drug-Drug Interactions with Orally Administered Medications . Clinical Pharmacokinetics . 59 . 4 . 447–462 . April 2020 . 31788764 . 7109143 . 10.1007/s40262-019-00844-3 .
  15. Book: Australian Medicines Handbook Pty Ltd . Australian Medicines Handbook 2022 . 2022 . 978-0-6485158-6-9 . Adelaide, SA.
  16. Web site: International Foundation for Functional Gastrointestinal Disorders, Inc. (IFFGD) . Antacids . https://web.archive.org/web/20160506182546/http://www.iffgd.org/site/manage-your-health/diet-treatments/antacids . 6 May 2016 . IFFGD Publication #520 . Thompson WG . 12 September 2014 .
  17. Barnett CC, Richardson CT . In vivo and in vitro evaluation of magnesium-aluminum hydroxide antacid tablets and liquid . Digestive Diseases and Sciences . 30 . 11 . 1049–1052 . November 1985 . 4053915 . 10.1007/BF01315602 . 8133980 .
  18. Web site: Maalox Antacid Oral: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing . 24 June 2022 . WebMD . 24 June 2022 . https://web.archive.org/web/20220624114050/https://www.webmd.com/drugs/2/drug-19216/maalox-antacid-oral/details . live .
  19. News: Dubogrey I . Putting the Fizz into Formulation. European Pharmaceutical Contractor. Autumn. 2013. 17 April 2017. 28 August 2021. https://web.archive.org/web/20210828151212/http://www.samedanltd.com/magazine/11/issue/204/article/3622. dead.
  20. Web site: Tablets . British Pharmacopeia . 2003 . https://web.archive.org/web/20130103012204/http://www.newdruginfo.com/pharmacopeia/bp2003/British%20Pharmacopoeia%20Volume%20III/Monographs/Formulated%20Preparations%20Genearal%20Monographs/TABLETS.htm . 3 January 2013 .
  21. Book: International Pharmacopoeia 2006. 1 July 2013. 2006. World Health Organization. 978-92-4-156301-7. 966.
  22. Web site: Alka Seltzer Directions of use, Sodium & Aspirin content – Alka Seltzer relief from Headaches, Migraine & Upset stomach. alkaseltzer.ie. 17 April 2017. https://web.archive.org/web/20150429145428/http://www.alkaseltzer.ie/en/about-alka-seltzer/. 29 April 2015. dead.
  23. Encyclopedia: Blair GT, DeFraties JJ . Kirk-Othmer Encyclopedia of Chemical Technology . Kirk Othmer Encyclopedia of Chemical Technology . 2000 . 1–19 . 10.1002/0471238961.0825041802120109.a01 . Hydroxy Dicarboxylic Acids . 978-0471238966 .
  24. Graham DY, Smith JL . Aspirin and the stomach . Annals of Internal Medicine . 104 . 3 . 390–398 . March 1986 . 3511824 . 10.7326/0003-4819-104-3-390 .
  25. Web site: 30 March 2023 . Which OTC Meds Treat Heartburn? . 8 January 2024 . WebMD.
  26. Web site: Eno – Summary of Product Characteristics at eMC . 2 September 2016 . Electronic Medicines Compendium . Last updated 1 January 2016.
  27. Web site: Gelusil - Uses, Side Effects, and More . 27 February 2024.

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