Antacids to Reduce Stomach Acid pH | Actions and Side Effects

What are antacids?

Antacids are alkalines that are used as acid-neutralizing agents for protection against stomach acidity related disorders. It is an inexpensive and safe over-the-counter (OTC) medication that is available in tablet or suspension form. It can neutralize the gastric acid fairly rapidly and is often used for immediate symptomatic relief. Antacids are available as single compounds or in combinations. To counteract side effects and limit the potential toxicity of a single compound, combination antacids are now more widely used. The type of antacids available include calcium carbonate, sodium bicarbonate and magnesium-aluminum hydroxide combinations.

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Action of Antacids

Antacids as weak bases, raise the pH of the stomach acid. This does not mean that the stomach secretions are now alkaline but rather that it is less acidic. When antacids make contact and react with stomach acid (HCl), water and a salt, like sodium chloride or calcium chloride, is formed. In addition, carbon dioxide gas may be produced. This contributes to intestinal gas, belching and flatulence.

Antacids are use in most hyperacidity conditions, including gastritis, dyspepsia and to relieve heartburn (burning chest pain) due to gastroesophageal reflux disese (acid reflux). In peptic ulcers, antacids may offer temporary symptomatic relief although when used with other ulcer medication, it can help the ulcer to heal by reducing the effect of the gastric acid irritant. Unlike other drugs, like proton pump inhibitors, antacids do not reduce gastric acid secretion although it may promote the production of prostaglandins. Its main action however, is to increase the pH of gastric acid.

Always use the antacid as advised on the drug information leaflet or based on your pharmacist’s recommendations or doctor’s prescription. Antacids are take orally after meals and often at bedtime as well. In severe gastritis, antacids may be taken more frequently, however, it is advisable to first seek advice from a medical professional. Antacid suspensions are faster acting and often seen as being more effective but antacid tablets are equally beneficial if it is chewed throughly. Despite the popularity of antacids, it does have a host of side effects that have to be considered by chronic users.

Side Effects of Antacids

The carbonate antacids (sodium bicarbonate and calcium carbonate) can cause excessive belching, nausea, abdominal distention, and flatulence. These antacids when used in high doses or in patient with kidney failure may result in  metabolic alkalosis.  The possibility of high calcium levels in the blood (hypercalcemia), kidney impairment (renal insufficiency) and metabolic alkalosis increases greatly if high doses of antacids are used with calcium containing milk products. This is know as milk-alkali syndrome.

Two compounds that are frequently used together are magnesium and aluminimum salts due to the opposite effects in may have on bowel movement. Whereas aluminium salts may result in constipation, magnesium can lead to diarrhea. By using both together, these opposite effects on the bowel movement are minimized.

Furthermore, high doses of aluminium which are absorbed into the bloodstream may accumulate in the body and lead to toxicity. This can possibly read to a host of bone, neurological and muscular conditions, especially in patients within impaired kidney function.  Therefore the use of two salts allows for the proper dose to neutralize gastric acid without allowing for toxicity by high doses of a single compound.

As with most medication, antacids can cause a rebound effect, which is that it may exacerbate the very condition that it was intended to alleviate. A rebound increase in gastric acid secretion is more likely to occur once chronic use of antacids have been discontinued. Antacids should be used cautiously when other drugs are being used simultaneously. It can affect the absorption of certain antibiotics and iron, and can also impair the action of other acid-reducing drugs like sucralfate. This interaction may be minimized by using antacids and other drugs at least 2 hours apart.

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