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GI PP
Acid Controlling Drugs
Question | Answer |
---|---|
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 |
Acid-Related Diseases | PUD, GERD, H. pylori |
Helicobacter 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 |
Types of Acid Controlling Drugs | Antacids, H2 antagonists, proton pump inhibitors |
Antacids | Antacids DO NOT prevent the overproduction of acid Antacids DO neutralize the acid once it is in the stomach |
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 |
Antacids | They are given prophylactically in the hospital for stress ulcers; give 30 min before meal and at bedtime. If your are giving with a medication that cannot be taken with an antacid: 1 hour before or 2 hours after. |
Antacids | Aluminum salts Magnesium salts Calcium salts Sodium bicarbonate |
Antacids: Aluminum Salts | Have constipating effects Often used with magnesium to counteract constipation Often recommended for patients with renal disease (more easily excreted) |
Antacids: Aluminum Salts, Examples | Aluminum carbonate: Basaljel Hydroxide salt: AlternaGEL Combination products (aluminum and magnesium): Gaviscon, Maalox, Mylanta, Di-Gel |
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 |
Antacids: Magnesium Salts, Examples | Hydroxide salt: magnesium hydroxide (Milk of Magnesia) – laxative (MOM) Carbonate salt: Gaviscon (also a combination product) Combination products such as Maalox, Mylanta (aluminum and magnesium) |
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 |
Antacids: Calcium Salts | 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) |
Antacids: Sodium Bicarbonate | Highly soluble Buffers the acidic properties of HCl Quick onset, but short duration |
Antacids: Sodium Bicarbonate | May cause metabolic alkalosis Sodium content may cause problems in patients with HF, hypertension, or renal insufficiency |
Simethicone | • Alters elasticity of mucus-coated bubbles, causing them to break • Used often, but there are limited data to support effectiveness |
Antacids: 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 |
Antacids: Implications | Patients with HF or hypertension should not use antacids with high sodium content 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: Implications | Antacids may cause premature dissolving of enteric-coated medications, resulting in stomach upset Be sure that chewable tablets are chewed thoroughly, and liquid forms are shaken well before giving |
Antacids: Implications | Administer with at least 8 ounces of water to enhance absorption (except for “rapid-dissolve” forms) Long-term self-medication with antacids may mask symptoms of serious underlying diseases, such as cancer or bleeding ulcers, or cardiac disease |
Antacids: Implications | If symptoms remain ongoing, patient should seek medical evaluation Monitor for adverse effects Nausea, vomiting, abdominal pain, diarrhea With calcium-containing products: constipation, acid rebound Monitor for therapeutic response |
Histamine Type 2 (H2) Antagonists | Reduce acid secretion cimetidine (Tagamet) famotidine (Pepcid) |
Histamine Type 2 (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 |
Histamine Type 2 (H2) Antagonists: Indications | GERD PUD Erosive esophagitis Adjunct therapy to control upper GI bleeding Pathologic gastric hypersecretory conditions |
H2 Antagonists: Drug Interactions | Smoking has been shown to decrease the effectiveness of H2 blockers |
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 |
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 |
Proton Pump Inhibitors: Mechanism of Action | 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 |
Proton Pump Inhibitors | omeprazole (Prilosec)* *First in this new class of drugs pantoprazole (Protonix) (IV form available) most often seen in hospital |
Proton Pump Inhibitors: Indications | GERD maintenance therapy Erosive esophagitis Short-term treatment of active duodenal and benign gastric ulcers Zollinger-Ellison syndrome Treatment of H. pylori–induced ulcers: Given with an antibiotic - Biaxin/Prilosec |
Proton Pump Inhibitors: Adverse Effects | Safe for short-term therapy Some approved for long-term therapy Adverse effects uncommon |
Proton Pump Inhibitors: 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 |
Proton Pump Inhibitors: Implications | 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 |
Proton Pump Inhibitors: Implications | 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 |
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 |
Sucralfate (Carafate) | Protects these areas from pepsin, which normally breaks down proteins (making ulcers worse) Little absorption from the gut May cause constipation, nausea, and dry mouth |
Sucralfate (Carafate) | 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 |
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 |
Assessment | Drugs such as cimetidine and famotidine should not be administered simultaneously with antacids. These drugs may be spaced 1 hour apart if both drugs need to be given. |
Teaching | If the patient is taking enteric-coated medications, the patient should know that the use of antacids may promote premature dissolution of the enteric coating. |
Teaching | Enteric coatings are used to diminish the stomach upset caused by irritating medications, and if the coating is destroyed early in the stomach, gastric upset may occur. |