Antacids: Nursing pharmacology

Definitions & Key takeaways

Antacids are medications that neutralize stomach acid. There are three types of antacids: aluminum hydroxide, magnesium carbonate, and calcium carbonate. Each type has its benefits and drawbacks.

Aluminum hydroxide is the most common type of antacid. It's available over-the-counter and is effective at neutralizing stomach acid. However, it can also cause constipation and has been linked to neurotoxicity. Magnesium carbonate is also available over-the-counter and is effective at neutralizing stomach acid. It doesn't cause as many side effects, but it can still cause diarrhea and abdominal pain. Calcium carbonate is another antacid that is available over-the-counter. It's effective at neutralizing stomach acid and can be taken long-term. However, it can cause constipation and gas.

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Revisores de contenido

Yifan Xiao, MD,Lisa Miklush, PhD, RNC, CNS

Antacids are acid reducing medications that directly lower the acidity of stomach contents. They are used to treat conditions like gastroesophageal reflux disorder, or GERD, and peptic ulcer disease, or (PUD).

When combined with antiflatulent medications like simethicone, they also help decrease gas production, which provides comfort and relief to clients experiencing gas or bloating. Antacids can be made up of aluminum, magnesium, calcium or sodium compounds.

Common antacid medications include: aluminum hydroxide, aluminum hydroxide and simethicone, magnesium hydroxide, magnesium hydroxide and aluminum hydroxide, magnesium trisilicate and aluminum hydroxide, magaldrate, calcium carbonate, calcium carbonate with magnesium hydroxide, and sodium bicarbonate.

Now when antacids are taken, the medication reacts with gastric acid and results in the production of neutral or low-acidity salts that increase the gastric pH. Additionally, the enzyme pepsin that normally helps digest protein is also inactivated.

The outcomes of these reactions are a decrease in gastric acidity, enhanced mucosal protection and a reduction of the symptoms associated with GI conditions such as GERD and PUD.

Antacids can cause several side effects If they are taken for an extended period of time, they may alter aluminum, calcium, sodium and phosphate levels.

Other general side effects of antacids include belching, constipation, flatulence, diarrhea and gastric distention.

Since all antacids increase gastric pH and can potentially bind with other drugs, absorption and effectiveness of medications taken along with antacids can be affected.

For example, they can increase oral absorption of medications that are weak bases, such as quinidine, an antiarrhythmic and anti-parasite medication; and decrease the oral absorption of medications that are weak acids, such as warfarin sodium.

Also, antacids can chelate, or bond, other medications in the GI tract, resulting in new complexes that are not absorbable.

This is especially common with medications such as tetracyclines, a class of antibiotics. So, spacing out antacids from other medications by 1-2 hours, or as prescribed, is important.

Depending on the medication’s compound, side effects can vary amongst different types of antacids.

For aluminum based antacids, constipation, hypophosphatemia, which can manifest as anorexia, malaise, tremors and muscle weakness; and aluminum toxicity with prolonged use can occur.

A common side effect of magnesium based antacids is diarrhea. However, when combined with an aluminum based compound, it is less likely to occur.

Calcium based antacids can cause hypercalcemia and metabolic alkalosis, and sodium bicarbonate antacids have the potential to worsen hypertension and the risk for heart failure, largely because of the sodium content it contains.