1、Antacids and Acid-Controlling Agents,Antacids H2 Antagonists Proton Pump Inhibitors,Acid-Related Pathophysiology,The stomach secretes: Hydrochloric acid (HCl) Bicarbonate Pepsinogen Intrinsic factor Mucus Prostaglandins,Instructors may want to use EIC Image #121: Stomach: Zones and Different Glands,
2、Glands of the Stomach,Cardiac Pyloric Gastric* *The gastric glands are the largest in number,Cells of the Gastric Gland,Parietal Chief Mucoid,Cells of the Gastric Gland,Parietal Cells Produce and secrete HCl Primary site of action for many acid-controller drugs,Cells of the Gastric Gland,Chief Cells
3、 Secrete pepsinogen, a proenzyme Pepsinogen becomes PEPSIN when activated by exposure to acid Pepsin breaks down proteins (proteolytic),Cells of the Gastric Gland,Mucoid Cells Mucus-secreting cells (surface epithelial cells) Provide a protective mucous coat Protects against self-digestion by HCl,Hyd
4、rochloric Acid,Secreted by the parietal cells Maintains stomach at a pH of 1 to 4 Secretion stimulated by: Large, fatty meals Excessive amounts of alcohol Emotional stress,Instructors may want to use EIC Image #123: Parietal Cell Stimulation and Secretion,Acid-Related Diseases,Caused by imbalance of
5、 the three cells of the gastric gland and their secretions Most common: Hyperacidity Most harmful: Peptic ulcer disease (PUD) Lay terms for overproduction of HCl by the parietal cells: indigestion, sour stomach, heartburn, acid stomach,Antacids: Mechanism of Action,Promote the gastric mucosal defens
6、e mechanisms Secretion of: Mucus: Protective barrier against HCl Bicarbonate: Helps buffer acidic properties of HCl Prostaglandins: Prevent activation of proton pump,Antacids: Mechanism of Action,Antacids DO NOT prevent the overproduction of acid. Acids DO neutralize the acid once its in the stomach
7、.,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.,Antacids,OTC formulations available as:Capsules and tablets PowdersCh
8、ewable tablets SuspensionsEffervescent granules and tablets,Antacids,Aluminum salts Magnesium salts Calcium salts Sodium bicarbonate Used alone or in combination,Antacids,Aluminum Salts Forms: carbonate, hydroxide, phosphate Have constipating effects Often used with magnesium to counteract constipat
9、ionExample: aluminum carbonate (Basaljel),Antacids,Magnesium Salts Forms: carbonate, hydroxide, oxide, trisilicate Commonly cause a laxative effect Usually used with other agents to counteract this effect Dangerous when used with renal failurethe failing kidney cannot excrete extra magnesium, result
10、ing in accumulationExamples: magnesium hydroxide (MOM); combination products such as Maalox, Mylanta (aluminum and magnesium),Antacids,Calcium Salts Forms: many, but carbonate is most common May cause constipation Their use may result in kidney stones Long duration of acid action may cause increased
11、 gastric acid secretion (hyperacidity rebound) Often advertised as an extra source of dietary calciumExample: Tums (calcium carbonate),Antacids,Sodium Bicarbonate Highly soluble Quick onset, but short duration May cause metabolic alkalosis Sodium content may cause problems in patients with CHF, hype
12、rtension, or renal insufficiency,Antacids and Antiflatulents,Antiflatulents: used to relieve the painful symptoms associated with gas Several agents are used to bind or alter intestinal gas, and are often added to antacid combination products.,Antacids and Antiflatulents,OTC Antiflatulents activated
13、 charcoal simethicone Alters elasticity of mucus-coated bubbles, causing them to break. Used often, but there are limited data to support effectiveness.,Antacids: Side Effects,Minimal, and depend on the compound used Aluminum and calcium Constipation Magnesium Diarrhea Calcium carbonate Produces gas
14、 and belching; often combined with simethicone,Antacids: Drug Interactions,Chelation Chemical binding, or inactivation, of another drug Chemical inactivation Produces insoluble complexes Result: reduced drug absorption,Antacids: Drug Interactions,Increased stomach pH Increased absorption of basic dr
15、ugs Decreased absorption of acidic drugs Increased urinary pH Increased excretion of acidic drugs Decreased excretion of basic drugs,Antacids: Nursing Implications,Assess for allergies and preexisting conditions that may restrict the use of antacids, such as: Fluid imbalances Renal disease CHF Pregn
16、ancy GI obstruction Patients with CHF or hypertension should use low-sodium antacids such as Riopan, Maalox, or Mylanta II.,Antacids: Nursing Implications,Use with caution with other medications due to the many drug interactions. Most medications should be given 1 to 2 hours after giving an antacid.
17、 Antacids may cause premature dissolving of enteric-coated medications, resulting in stomach upset.,Antacids: Nursing Implications,Be sure that chewable tablets are chewed thoroughly, and liquid forms are shaken well before giving. Administer with at least 8 ounces of water to enhance absorption (ex
18、cept for the “rapid dissolve” forms). Caffeine, alcohol, harsh spices, and black pepper may aggravate the underlying GI condition.,Antacids: Nursing Implications,Monitor for side effects: Nausea, vomiting, abdominal pain, diarrhea With calcium-containing products: constipation, acid rebound Monitor
19、for therapeutic response: Notify heath care provider if symptoms are not relieved.,Histamine Type 2 (H2) Antagonists,H2 Antagonists,Reduce acid secretion All available OTC Most popular drugs for treatment of acid-related disorderscimetidine (Tagamet) famotidine (Pepcid) nizatidine (Axid) ranitidine
20、(Zantac),H2 Antagonists: Mechanism of Action,Block histamine (H2) at the receptors of acid-producing parietal cells Production of hydrogen ions is reduced, resulting in decreased production of HCl,H2 Antagonists: Drug Effect,Suppressed acid secretion in the stomach,H2 Antagonists: Therapeutic Uses,S
21、hown to be effective for: Gastric ulcer Gastroesophageal reflux disease (GERD) Upper GI Duodenal ulcer (with or bleeding without H. pylori) May be effective for: Stress ulcers Peptic esophagitis Prevention and management of allergic conditions, when used with H1 blockers,H2 Antagonists: Side Effects
22、,Overall, less than 3% incidence of side effects Cimetidine may induce impotence and gynecomastia,H2 Antagonists: Drug Interactions,Cimetidine 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 inhi
23、bit the absorption of drugs that require an acidic GI environment for absorption.,H2 Antagonists: Drug Interactions,SMOKING has been shown to decrease the effectiveness of H2 blockers,H2 Antagonists: Nursing Implications,Assess for allergies and impaired renal or liver function. Use with caution in
24、patients who are confused, disoriented, or elderly. Take 1 hour before or after antacids. Ranitidine may be given intravenously; follow administration guidelines.,Proton Pump Inhibitors,Proton Pump Inhibitors,The parietal cells release positive hydrogen ions (protons) during HCl production. This pro
25、cess is called the “proton pump.” H2 blockers and antihistamines do not stop the action of this pump.,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. Result: AchlorhydriaAL
26、L gastric acid secretion is blocked. In order to return to normal acid secretion, the parietal cell must synthesize new H+/K+ ATPase.,Proton Pump Inhibitors: Drug Effect,Total inhibition of gastric acid secretionlansoprazole (Prevacid) omeprazole (Prilosec)rabeprazole (Aciphex) pantoprazole (Protoni
27、x)esomeprazole (Nexium),Proton Pump Inhibitors: Therapeutic Uses,GERD maintenance therapy Erosive esophagitis Short-term treatment of active duodenal and benign gastric ulcers Zollinger-Ellison syndrome Treatment of H. pylori-induced ulcers,Proton Pump Inhibitors: Side Effects,Safe for short-term th
28、erapy Incidence low and uncommon,Proton Pump Inhibitors: Nursing Implications,Assess for allergies and history of liver disease Pantoprazole is the only proton pump inhibitor available for parenteral administration, and can be used for patients who are unable to take oral medications May increase se
29、rum levels of diazepam, phenytoin, and cause increased chance for bleeding with warfarin,Proton Pump Inhibitors: Nursing Implications,Instruct the patient taking omeprazole: It should be taken before meals. The capsule should be swallowed whole, not crushed, opened or chewed. It may be given with an
30、tacids. Emphasize that the treatment will be short-term.,Other Drugs,sucralfate (Carafate) misoprostol (Cytotec),Sucralfate (Carafate),Cytoprotective agent Used for stress ulcers, erosions, PUD Attracted to and binds to the base of ulcers and erosions, forming a protective barrier over these areas P
31、rotects these areas from pepsin, which normally breaks down proteins (making ulcers worse),Sucralfate (Carafate),Little absorption from the gut May cause constipation, nausea, and dry mouth May impair absorption of other drugs, especially tetracycline Binds with phosphate; may be used in chronic ren
32、al failure to reduce phosphate levels Do not administer with other medications,misoprostol (Cytotec),Synthetic prostaglandin analogue 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,misoprostol (Cytotec),Used for prevention of NSAID-induced gastric ulcers Doses that are therapeutic enough to treat duodenal ulcers often produce abdominal cramps, diarrhea,
