Acid reducing medications

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Acid reducing medications

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Acid reducing medications


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Acid reducing medications

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A 55-year-old man comes to the office because of severe diarrhea for the past three days. Diarrhea developed suddenly, is non-bloody, and has not been associated with abdominal pain. He has also experienced chronic symptoms of epigastric burning and an acid taste in the mouth, for which he recently started taking over-the-counter medication. The patient’s BMI is 32 kg/m2. Vitals are within normal limits. Which of the following medications is most likely responsible for this patient’s current presentation?  

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Acid reflux

proton pump inhibitors for p. 408

Adverse effects/events

proton pump inhibitors p. 407

Clostridium difficile p. , 136

proton pump inhibitor use p. 407

Gastritis p. 388

proton pump inhibitors for p. 408

Peptic ulcer disease p. 389

proton pump inhibitors for p. 407

Proton pump inhibitors (PPIs) p. 407

acute interstitial nephritis p. 626

Beers criteria p. 248

gastrin and p. 380

for Helicobacter pylori p. , 144

naming convention for p. 255

Zollinger-Ellison syndrome p. 359

proton pump inhibitors for p. 408

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Acid reducing medications include antacids that directly lower the acidity of stomach contents, and antisecretory medications that act on parietal cells in the stomach to decrease acid secretion. They are used to treat conditions like gastroesophageal reflux disorder and peptic ulcer disease by decreasing the acidity of the stomach and allowing the epithelial linings to heal.

Now, the stomach is composed of four regions: the cardia, the fundus, the body, and the pyloric antrum. There’s also a pyloric sphincter, or valve, at the end of the stomach, which closes while eating, keeping food inside for the stomach to digest. The epithelial layer of the stomach contains different gastric glands which secrete a variety of substances.

Starting with the cardia, it contains mostly foveolar cells that secrete a protective mucus, which is mostly made up of water and glycoproteins. The fundus and the body contain both the parietal cells and enterochromaffin-like cells, and the antrum and pyloric areas contain G-cells. Now gastric acid is mainly composed of HCl, or hydrochloric acid, which is mainly secreted by the parietal cells. Parietal cells have M3, CCK2, and H2 membrane receptors, which modulate their secretory behavior. When food enters the stomach, it causes the stomach walls to expand, which leads to the activation of these receptors.

First, stomach expansion causes the branches of the vagus nerve that innervates the stomach to release acetylcholine, which activates M3 receptors. Next, the G cells in the antrum of the stomach release gastrin, which activate the CCK2 receptors. Gastrin and acetylcholine activate the enterochromaffin-like cells, which release histamine, that then activates H2 receptors.

Activation of M3, CCK2, and H2 receptors increases the conversion of H20 and CO2 to H+ and HCO3- by carbonic anhydrase. The H+ is then pumped out of the cell and into the stomach via the H+/K+-ATPase pump. These H+ ions combine with Cl- ions to form hydrochloric acid and decrease the pH in the stomach.

Normally, the stomach is protected from the acidic environment by the mucus secreted by foveolar cells. However, if there’s an imbalance between mucus and acid secretion, like in Zollinger-Ellison syndrome, which is caused by a gastrin secreting tumor, it could lead to damage of the stomach. This could manifest as chronic gastritis and gastric, or peptic ulcers. Now, in the esophagus, the lower esophageal sphincter prevents most of the gastric acid from coming back up when the stomach is full or when you’re laying down. If this sphincter is loose, the acid could reflux into the lower esophagus and erode the esophageal lining. This is called GERD, or gastroesophageal reflux disease, most commonly known as heartburn. One way to mitigate the harmful effects of gastrin in these disorders is to decrease its acidity through medications.


Acid-reducing medications are a type of drugs that work to reduce the amount of acid in a person's stomach. There are three main groups of acid-reducing medications. The most common type is called a proton pump inhibitor (PPI). This type of medication inhibits the enzyme called H, K-ATPase, which blocks gastric acid secretion by parietal cells of the stomach. PPIs include drugs like omeprazole, esomeprazole, and pantoprazole.

The second group consists of H2 receptor blockers. H2 receptor blockers work by blocking histamine H2 receptors located on parietal cells of the stomach. This in turn inhibits the release of gastric acid. Examples of H2 receptor blockers include cimetidine, famotidine, and nizatidine. The last group consists of antacids, which work by neutralizing stomach acid that's already been produced. Examples of antacids include magnesium trisilicate and aluminum hydroxide.


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  2. "Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th Edition" McGraw-Hill Education / Medical (2017)
  3. "Rang and Dale's Pharmacology" Elsevier (2019)
  4. "Peptic ulcer disease" Am Fam Physician (2007)
  5. "Proton Pump Inhibitors, H2-Receptor Antagonists, Metformin, and Vitamin B-12 Deficiency: Clinical Implications" Advances in Nutrition (2018)
  6. "25 Years of Proton Pump Inhibitors: A Comprehensive Review" Gut and Liver (2017)

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