Stomach Glands and Cells

• The stomach secretes hydrochloric acid, bicarbonate, pepsinogen, intrinsic factor, mucus, and prostaglandins.

Glands of the Stomach

• The three main glands include cardiac (gastroesophageal sphincter), pyloric, and gastric.
• Gastric gland cells are the most numerous and important for acid control.

Cells of the Gastric Gland

• Parietal cells produce and secrete hydrochloric acid.
• Parietal cells are the primary site of action for many drugs treating acid-related disorders.
• Chief cells secrete pepsinogen, which becomes pepsin when activated by acid, and pepsin breaks down proteins.
• Mucous cells are mucus-secreting cells that provide a protective mucus coat to protect against self-digestion.

Hydrochloric Acid

• Parietal cells secrete hydrochloric acid when stimulated by food, caffeine, chocolate, and alcohol.
• Hydrochloric acid maintains a stomach pH of 1 to 4 and aids in food digestion and defenses against microbial infection.
• Secretion also occurs in response to large fatty meals and emotional stress.

Acid-Related Diseases

• Peptic ulcer disease involves gastric or duodenal ulcers with digestion of the gastrointestinal mucosa by pepsin.
• Helicobacter pylori, a bacterium, is found in the gastrointestinal tract of 90% of patients with duodenal ulcers and 70% of those with gastric ulcers.
• H. pylori is treated by triple therapy, using a PPI, clarithromycin, and amoxicillin or metronidazole, or quadruple therapy using a PPI, bismuth subsalicylate, tetracycline, and metronidazole for 7-14 days.

Stress-Related Mucosal Damage

• Gastrointestinal lesions are common in Critical Care Unit patients, especially within the first 24 hours after admission.
• Factors like decreased blood flow, mucosal ischemia, hypoperfusion, and reperfusion injury contribute to stress-related mucosal damage.
• Nasogastric tubes and ventilators increase the risk of gastrointestinal bleeding
• A histamine receptor-blocking drug or a PPI are administered for prevention.

Types of Acid-Controlling Drugs

• Antacids, H₂ antagonists, and PPIs are the main types of acid-controlling drugs.

Antacids

• Neutralize stomach acid, and commonly contain salts of aluminum, magnesium, calcium, or sodium bicarbonate.
• Many antacid preparations contain simethicone.
• Formulations with aluminum and calcium often include magnesium to enhance acid neutralization and counteract constipation.

Antacid Considerations

• Calcium antacids can lead to kidney stones and increased gastric acid secretion.
• Magnesium-containing antacids should be avoided in patients with renal failure.
• Sodium bicarbonate is a quick-acting but short-lasting antacid.
• Antacids do not prevent overproduction, but neutralize acid secretions and promote gastric mucosal defense, and stimulate mucus secretion, bicarbonate, and prostaglandins.
• Raising gastric pH by one point can neutralize up to 90% of gastric acid.
• By reducing acidity, antacids reduce pain by inhibiting pepsin's ability to digest protein, increasing the stomach's resistance to irritation and increasing the tone of the cardiac sphincter.

Antacid Relief

• Antacids provide acute relief for peptic ulcer, gastritis, gastric hyperacidity, and heartburn symptoms.

Antacid Contraindications

• Known allergies, severe renal failure, electrolyte imbalances, and gastrointestinal obstruction.

Antacid Formulations

• Antacids are typically available over-the-counter, and come in capsule, tablet, powder, chewable tablet, suspension, and effervescent granule forms.

Antacid Types

• Common antacid types used alone or in combination include aluminum hydroxide, magnesium hydroxide, simethicone, and combination aluminum/magnesium hydroxide which may contain a local anaesthetic (Mucaine).

Antacids: Aluminum Salts

• Aluminum salts have constipating effects.
• They are often used with magnesium to counteract constipation.
• Commonly prescribed for patients with renal disease to help excrete more easily.
• Combination product examples include: Antacid Plus®, Diovol®, Gelusil®, Maalox®, Multiaction®.

Antacids: Magnesium Salts

• Magnesium salts commonly cause diarrhea; thus, frequently paired with other drugs to counter this effect.
• Magnesium antacids are dangerous when used with renal failure, potentially resulting in accumulation.
• Combination product: Magnesium hydroxide and mineral oil (Magnolox®)

Antacids: Calcium Salts

• Calcium carbonate is the most common form.
• These may cause constipation and kidney stones.
• Also not recommended for patient with renal disease since they may accumulate to toxic levels
• Long duration of acid action may cause increased gastric acid secretion.
• Commonly contain calcium carbonate and simethicone.
• Often presented as an extra source of calcium

Antacids: Sodium Bicarbonate

• Sodium bicarbonate is highly soluble
• It buffers the acidic properties of hydrochloric acid.
• Sodium bicarbonate features a quick onset but short duration.
• It may cause metabolic alkalosis.
• High sodium content makes it unsuitable for patients with heart failure, hypertension, or renal insufficiency.

Antacids and Antiflatulents

• Antiflatulents such as simethicone relieve painful symptoms associated with gas and are often included in antacid combinations.

Antacid Adverse Effects

• The adverse effects of antacids are minimal and depend on the compound: overuse may result in metabolic alkalosis, aluminium and calcium may cause constipation, magnesium can cause diarrhea, and calcium can result in kidney stones and rebound hyperacidity.
• Calcium carbonate may produce gas and belching often combined with simethicone

Antacid Drug Interactions

• Adsorption of other drugs to antacids reduces absorption.
• Chelation inactivates drugs and reduces drug absorption.
• Increased stomach acidity from antacids increases absorption of basic drugs, while the inverse is true for acidic drugs.
• Increased urinary pH from antacids increases the excretion of acidic drugs, while the inverse is true for basic drugs.

H2 Receptor Antagonists

• These reduce acid secretion and are available OTC in lower dosages.
• cimetidine, ranitidine hydrochloride (Zantac®), and famotidine (Pepcid®) are examples of H2 receptor antagonists.
• Competitively block the H2 receptor of acid-producing parietal cells, reducing hydrogen ion secretion and increasing stomach pH.
• They are used to relieve symptoms associated with hyperacidity-related conditions such as gastroesophageal reflux disease (GERD), peptic ulcer disease, erosive esophagitis, adjunct therapy to control upper gastrointestinal bleeding and Zollinger-Ellison syndrome.
• Has suppressed acid secretion in the stomach

H2 Antagonists: Adverse Effects

• Overall, there are very few adverse effects.
• Central nervous system issues, including confusion and disorientation may occur in elderly patient.
• Cimetidine may cause erectile dysfunction and gynecomastia.
• Thrombocytopenia has been reported with ranitidine hydrochloride and famotidine.

H2 Antagonists: Drug Interactions

• Cimetidine binds with the P-450 microsomal oxidase system in the liver, inhibiting the oxidation of many drugs and increasing the drug levels.
• All H2 antagonists may inhibit the absorption of drugs that require an acidic gastrointestinal environment for absorption.
• Because of its potential to cause drug interactions, cimetidine has been largely replaced.
• Cimetidine is still used to treat certain allergic reactions.
• Smoking decreases the effectiveness of H₂ blockers and H₂ receptor antagonists work best when taken one hour before antacids.

famotidine (Pepcid®)

• The last H2 receptor antagonist introduced with minimal drug interaction concerns.

Proton Pump Inhibitors

• Parietal cells release positive hydrogen ions (protons) during hydrochloric acid production, this process is called the proton pump.
• H2 blockers and antihistamines do not stop the action of this pump.
• lansoprazole (Prevacid®), omeprazole (Losec®), rabeprazole sodium (Pariet®), pantoprazole sodium (Pantoloc®), esomeprazole trihydrate (Nexium®) and dexlansoprazole (Dexilant®) are examples of PPIs.
• They irreversibly bind to the H+/K+ adenosine triphosphatase (ATPase) enzyme which prevents hydrogen ions from moving from the parietal cells into the stomach.
• The parietal cells must synthesize new H+/K+ ATPase to return to normal acid secretion.
• The irreversible binding results in achlorhydria.

Proton Pump Inhibitors: Indications

• Treat gastroesophageal reflux disease, erosive esophagitis, short-term treatment of active duodenal and benign gastric ulcers, Zollinger-Ellison syndrome, nonsteroidal anti-inflammatory drug (NSAID)–induced ulcers, stress ulcer prophylaxis, and H. pylori–induced infections (given with an antibiotic).

Proton Pump Inhibitors: Adverse Effects

• PPIs are generally well tolerated; however, long-term use may cause a predisposition to gastrointestinal infections like Clostridium difficile, osteoporosis, and increased risk of fractures, pneumonia, and magnesium depletion.

Proton Pump Inhibitors: Drug Interactions

• PPIs may increase serum levels of diazepam and phenytoin and increase the chance of bleeding with warfarin, also affects the absorption of ketoconazole, ampicillin, iron salts, and digoxin.
• Clopidogrel, sucralfate may delay the absorption and food can decrease the absorption of PPIs.
• Omeprazole magnesium (Losec) was the first generation of antisecretory drugs, orally administered PPIs and H2 receptor antagonists often work best when taken 30-60 minutes before meals.
• Lansoprazole (Prevacid) is available in a sustained release capsule and cannot be crushed, administered via apple juice for nasogastric tube.

Miscellaneous Acid-Controlling Drugs

• sucralfate, misoprostol, and simethicone (Ovol®) are examples of these types of drugs.

Sucralfate

• It is a cytoprotective drug used to treat stress ulcers and peptic ulcer disease.
• Binds to the base of ulcers and provide a protective barrier from pepsin.
• There is little absorption from the gut.
• It may cause constipation, nausea, and dry mouth and may impair absorption of other drugs; therefore, separate by at least 2 hours.
• It should not be used with other medications.
• It binds with phosphate and be used in chronic renal failure to reduce phosphate levels.

Misoprostol

• Misoprostol is a prostaglandin E analogue with cytoprotective activity.
• Protects gastric mucosa and also is to promote local cell regeneration and maintain mucosal blood flow.
• Used to prevent NSAID-induced gastric ulcers.
• Higher doses used to treat duodenal ulcers may cause abdominal cramps and diarrhea.
• It induces uterine contractions and it is not safe in pregnancy.

Simethicone

• It is a antiflatulent drug that reduces the discomforts of gastric or intestinal gas.
• Alters elasticity of mucus-coated gas bubbles, breaking them into smaller ones for decreased gas pain and easier expulsion.

Nursing Implications: Antacids

• Assess for pre-existing conditions that restrict the use: allergies, fluid imbalances, renal disease, gastrointestinal obstruction, heart failure, and pregnancy.
• Patients with heart failure or hypertension should not use antacids with high sodium content.
• Caution is needed with other medications due to drug interactions.
• Administer antacids 1 to 2 hours apart from other medications..
• Monitor for adverse effect (nausea, vomiting, abdominal pain, diarrhea), or those with calcium (constipation, acid rebound).

H2 Antagonists: Nursing Implications

• Assess for allergies and impaired function of the renal or liver.
• Used with caution in patients who are confused, disoriented, or in older adults.
• Take 1-2hrs before taking antacids.

Proton Pump Inhibitors: Nursing Implications

• Assess for allergies and liver diseases.
• Not all are available for administration
• Monitor for side effects
• For nasogastric tubes, make sure you giving the right capsules.

Antidiarrheal

• Indicated for use in antibiotics
• Is often given with the anticholiergics

Irritable Bowel Syndrome

• Is a chronic intestinal discomfort

Nursing Implications: Antacids

• Watch for a history (precipitating factors)
• Access the current medications

Nursing Implications

• Drugs may result in drowsiness
• Stay away from all hazardous activities
• Don't take antiemetics with alcohol