Acid-Controlling Drugs

1. Acid-Controlling Drugs Fall 2012

2. Hydrochloric Acid Secreted by parietal cells when stimulated by food Maintains stomach at pH of 1 to 4 Secretion also stimulated by: Large fatty meals Excessive amounts of alcohol Emotional stress Fall 2012

3. Acid-Related Diseases Caused by imbalance of the three cells of the gastric gland and their secretions Most common: hyperacidity Lay terms for overproduction of HCl by the parietal cells: Indigestion, sour stomach, heartburn, acid stomach Fall 2012

4. Acid-Related Diseases (cont’d) Peptic ulcer disease (PUD) Gastroesophageal reflux disease (GERD) Helicobacter pylori (H. pylori) Bacterium found in GI tract of 90% of patients with duodenal ulcers and 70% of those with gastric ulcers Can be detected by serum antibody tests Antibiotics are used to eradicate H. pylori Fall 2012

5. Types of Acid-Controlling Drugs Antacids H2 antagonists Proton pump inhibitors Fall 2012

6. Antacids: Mechanism of Action Neutralize stomach acid Promote gastric mucosal defense mechanisms Secretion of: Mucus: protective barrier against HCl Bicarbonate: helps buffer acidic properties of HCl Fall 2012

7. Antacids: Mechanism of Action (cont’d) Antacids DO NOT prevent the overproduction of acid Antacids DO neutralize the acid once it is in the stomach Fall 2012

8. Antacids: Drug Effects Reduction of pain associated with acid-related disorders Raising gastric pH from 1.3 to 1.6 neutralizes 50% of the gastric acid Raising gastric pH 1 point (1.3 to 2.3) neutralizes 90% of the gastric acid Reducing acidity reduces pain Fall 2012

9. Antacids Over-the-counter formulations available as: Capsules and tablets Powders Chewable tablets Suspensions Effervescent granules and tablets Fall 2012

10. Antacids (cont’d) Used alone or in combination Aluminum salts Magnesium salts Calcium salts Sodium bicarbonate Fall 2012

11. Antacids: Aluminum Salts Have constipating effects Often used with magnesium to counteract constipation Often recommended for patients with renal disease (more easily excreted) Examples Aluminum carbonate: Basaljel Hydroxide salt: AlternaGEL Combination products (aluminum and magnesium): Gaviscon, Maalox, Mylanta, Di-Gel Fall 2012

12. Antacids: Magnesium Salts Commonly cause diarrhea; usually used with other drugs to counteract this effect Dangerous when used with renal failure—the failing kidney cannot excrete extra magnesium, resulting in accumulation Fall 2012

13. Antacids: Magnesium Salts (cont’d) Examples Hydroxide salt: magnesium hydroxide (Milk of Magnesia) Carbonate salt: Gaviscon (also a combination product) Combination products such as Maalox, Mylanta (aluminum and magnesium) Fall 2012

14. Antacids: Calcium Salts Many forms, but carbonate is most common May cause constipation, kidney stones Also not recommended for patients with renal disease—may accumulate to toxic levels Long duration of acid action—may cause increased gastric acid secretion (hyperacidity rebound) Often advertised as an extra source of dietary calcium Example: Tums (calcium carbonate) Fall 2012

15. Antacids: Sodium Bicarbonate Highly soluble Buffers the acidic properties of HCl Quick onset, but short duration May cause metabolic alkalosis Sodium content may cause problems in patients with HF, hypertension, or renal insufficiency Fall 2012

16. Antacids and Antiflatulents Antiflatulents: used to relieve the painful symptoms associated with gas Several drugs are used to bind or alter intestinal gas and are often added to antacid combination products Fall 2012

17. Antacids and Antiflatulents (cont’d) Over-the-counter antiflatulents Activated charcoal Simethicone Alters elasticity of mucus-coated bubbles, causing them to break Used often, but there are limited data to support effectiveness Fall 2012

18. Antacids: Adverse Effects Minimal, and depend on the compound used Aluminum and calcium Constipation Magnesium Diarrhea Calcium carbonate Produces gas and belching; often combined with simethicone Fall 2012

19. Antacids: Drug Interactions Adsorption of other drugs to antacids Reduces the ability of the other drug to be absorbed into the body Chelation Chemical binding, or inactivation, of another drug Produces insoluble complexes Result: reduced drug absorption Fall 2012

20. Antacids: Drug Interactions (cont’d) Increased stomach pH Increased absorption of basic drugs Decreased absorption of acidic drugs Increased urinary pH Increased excretion of acidic drugs Decreased excretion of basic drugs Fall 2012

21. Antacids: Nursing Implications Assess for allergies and preexisting conditions that may restrict the use of antacids, such as: Fluid imbalances Renal disease GI obstruction Heart failure (HF) Pregnancy Patients with HF or hypertension should not use antacids with high sodium content Fall 2012

22. Antacids: Nursing Implications (cont’d) Use with caution with other medications because of the many drug interactions Most medications should be given 1 to 2 hours after giving an antacid Antacids may cause premature dissolving of enteric-coated medications, resulting in stomach upset Fall 2012

23. Antacids: Nursing Implications (cont’d) Long-term self-medication with antacids may mask symptoms of serious underlying diseases, such as cancer or bleeding ulcers If symptoms remain ongoing, patient should seek medical evaluation Fall 2012

24. Histamine Type 2 (H2) Antagonists Reduce acid secretion All available over the counter in lower dosage forms Most popular drugs for treatment of acid-related disorders cimetidine (Tagamet) nizatidine (Axid) famotidine (Pepcid) ranitidine (Zantac) Fall 2012

25. H2 Antagonists: Mechanism of Action Block histamine at the (H2) receptors of acid-producing parietal cells Production of hydrogen ions is reduced, resulting in decreased production of HCl Fall 2012

26. H2 Antagonists: Drug Effect and Indications Drug effect Suppressed acid secretion in the stomach Indications GERD PUD Erosive esophagitis Adjunct therapy to control upper GI bleeding Pathologic gastric hypersecretory conditions Fall 2012

27. H2 Antagonists: Adverse Effects Overall, very few adverse effects Cimetidine may induce impotence and gynecomastia May cause headaches, lethargy, confusion, diarrhea, urticaria, sweating, flushing, other effects Fall 2012

28. H2 Antagonists: Drug Interactions cimetidine (Tagamet) Binds with P-450 microsomal oxidase system in the liver, resulting in inhibited oxidation of many drugs and increased drug levels All H2 antagonists may inhibit the absorption of drugs that require an acidic GI environment for absorption Fall 2012

29. H2 Antagonists: Drug Interactions (cont’d) Smoking has been shown to decrease the effectiveness of H2 blockers Fall 2012

30. H2 Antagonists: Nursing Implications Assess for allergies and impaired renal or liver function Use with caution in patients who are confused, disoriented, or elderly Take 1 hour before or after antacids For intravenous doses, follow administration guidelines Fall 2012

31. Proton Pump Inhibitors The parietal cells release positive hydrogen ions (protons) during HCl production This process is called the proton pump H2 blockers and antihistamines do not stop the action of this pump Fall 2012

32. Proton Pump Inhibitors: Mechanism of Action Irreversibly bind to H+/K+ ATPase enzyme This bond prevents the movement of hydrogen ions from the parietal cell into the stomach Results in achlorhydria—ALL gastric acid secretion is temporarily blocked To return to normal acid secretion, the parietal cell must synthesize new H+/K+ ATPase Fall 2012

33. Proton Pump Inhibitors: Drug Effect Total inhibition of gastric acid secretion lansoprazole (Prevacid) omeprazole (Prilosec) rabeprazole (AcipHex) pantoprazole (Protonix) (IV form available) esomeprazole (Nexium) Fall 2012

34. Proton Pump Inhibitors: Indications GERD maintenance therapy Erosive esophagitis Short-term treatment of active duodenal and benign gastric ulcers Treatment of H. pylori–induced ulcers Given with an antibiotic Fall 2012

35. Proton Pump Inhibitors: Adverse Effects Safe for short-term therapy Some approved for long-term therapy Adverse effects uncommon Fall 2012

36. Proton Pump Inhibitors: Nursing Implications Assess for allergies and history of liver disease Not all are available for parenteral administration May increase serum levels of diazepam and phenytoin; may increase chance for bleeding with warfarin Fall 2012

37. Proton Pump Inhibitors: Nursing Implications (cont’d) The granules of pantoprazole capsules may be given via NG tubes, but the NG tube must be at least 16 g or the tube may become clogged Capsule contents may be opened and mixed with apple juice, but do not chew or crush delayed-release granules Proton pump inhibitors often work best when taken 30 to 60 minutes before meals Fall 2012

38. Other Drugs sucralfate (Carafate) misoprostol (Cytotec) simethicone (Mylicon) Fall 2012

39. Sucralfate (Carafate) Cytoprotective drug Used for stress ulcers, peptic ulcer disease Attracted to and binds to the base of ulcers and erosions, forming a protective barrier over these areas Protects these areas from pepsin, which normally breaks down proteins (making ulcers worse) Fall 2012

40. Sucralfate (Carafate) (cont’d) Little absorption from the gut May cause constipation, nausea, and dry mouth May impair absorption of other drugs—give other drugs at least 2 hours before sucralfate Do not administer with other medications Binds with phosphate; may be used in chronic renal failure to reduce phosphate levels Fall 2012

41. Misoprostol (Cytotec) Synthetic prostaglandin analog Prostaglandins have cytoprotective activity Protect gastric mucosa from injury by enhancing local production of mucus or bicarbonate Promote local cell regeneration Help to maintain mucosal blood flow Fall 2012

42. Misoprostol (Cytotec) (cont’d) Used for prevention of NSAID-induced gastric ulcers Doses that are therapeutic enough to treat duodenal ulcers often produce abdominal cramps, diarrhea Fall 2012

43. Simethicone Antiflatulent drug Used to reduce the discomforts of gastric or intestinal gas (flatulence) Alters elasticity of mucus-coated gas bubbles, breaking them into smaller ones Result is decreased gas pain and increased expulsion via mouth or rectum Fall 2012

44. Bowel Disorder Drugs Fall 2012

45. Diarrhea Abnormal passage of stools with increased frequency, fluidity, and weight, or with increased stool water excretion Fall 2012

46. Diarrhea (cont’d) Acute diarrhea Sudden onset in a previously healthy person Lasts from 3 days to 2 weeks Self-limiting Resolves without sequelae Fall 2012

47. Diarrhea (cont’d) Chronic diarrhea Lasts for more than 3 weeks Associated with recurring passage of diarrheal stools, fever, loss of appetite, nausea, vomiting, weight loss, and chronic weakness Fall 2012

48. Causes of Diarrhea Acute DiarrheaChronic Diarrhea Bacterial Tumors Viral Diabetes mellitus Drug induced Addison’s disease Nutritional factors Hyperthyroidism Protozoa Irritable bowel syndrome AIDS Fall 2012

49. Antidiarrheals: Mechanism of Action Adsorbents Coat the walls of the GI tract Bind to the causative bacteria or toxin, which is then eliminated through the stool Examples: bismuth subsalicylate (Pepto-Bismol), activated charcoal, aluminum hydroxide, others Fall 2012

50. Antidiarrheals: Mechanism of Action (cont’d) Antimotility drugs: anticholinergics Decrease intestinal muscle tone and peristalsis of GI tract Result: slows the movement of fecal matter through the GI tract Examples: belladonna alkaloids (atropine, hyoscyamine) Fall 2012