Antacids

Antacids

Antacids are over-the-counter (OTC) medications that are used asadjunct therapy to treat peptic ulcers. They include:

·                 aluminum carbonate gel

·                 calcium carbonate

·                 magaldrate (aluminum-magnesium complex)

·                 magnesium hydroxide and aluminum hydroxide

·                  simethicone.

Pharmacokinetics

Antacids work locally in the stomach by neutralizing gastric acid.They don’t need to be absorbed to treat peptic ulcers.

Distribution and excretion

Antacids are distributed throughout the GI tract and are eliminat-ed primarily in stool.

Pharmacodynamics

The acid-neutralizing action of antacids reduces the total amount of acid in the GI tract, allowing peptic ulcers to heal.

The more it works, the sooner it rests

Pepsin, one of the stomach secretions, acts more effectively when the stomach is highly acidic; therefore, as acidity drops, pepsin ac-tion is also reduced. Contrary to popular belief, antacids don’t work by coating peptic ulcers or the lining of the GI tract.

Pharmacotherapeutics

Antacids are primarily prescribed to relieve pain and are used ad-junctively in peptic ulcer disease.

Settling the GI system

Antacids also relieve symptoms of acid indigestion, heartburn, dyspepsia (burning or indigestion), or gastroesophageal reflux dis-ease (GERD), in which the contents of the stomach and duode-num flow back into the esophagus.

Fighting phosphate

Antacids may be used to control hyperphosphatemia (elevated blood phosphate levels) in kidney failure. Because calcium binds with phosphate in the GI tract, calcium carbonate antacids pre-vent phosphate absorption.

Drug interactions

All antacids can interfere with the absorption of oral drugs given at the same time. Absorption of digoxin, phenytoin, ketoconazole, iron salts, isoniazid, quinolones, and tetracyclines may be reduced if taken within 2 hours of antacids. (See Adverse reactions toantacids.)