1. PTP 546 Module 12: Gastrointestinal Pharmacology Jayne Hansche Lobert, MS, RN, ACNS-BC, NP 1Lobert

2. Gastrointestinal Pharmacology Drugs to treat gastric acidity and secretion – Antacids Ex: Aluminum Hydroxide (Maalox) Ex: Calcium Carbonate(Mylanta) – Histamine (H2) Receptor Blockers Ex: Famotidine (Pepcid) Ex: Ranitidine (Zantac) – Proton Pump Inhibitors Ex: Omeprazole (Prilosec) Ex: Esomeprazole (Nexium) 2Lobert

3. Gastrointestinal Pharmacology Antacids – Ex: Aluminum Hydroxide (Amphogel; Maalox) – Ex: Magnesium Hydroxide (Riopan) – Ex: Calcium Carbonate (Tums, Mylanta) – Ex: Sodium Bicarbonate (Alka-Seltzer, Baking Soda) – Action: med combines with hydrochloric acid (HCL) to form a salt and water  neutralization of hydrochloric acid  alters gastric pH – Therapeutic Effect: treatment of gi discomfort, transient dyspepsia, indigestion & heartburn by the neutralization of gastric acids – Side Effects: constipation with aluminum based antacids, diarrhea with magnesium based antacids; will alter metabolism of drugs requiring acidic environment for absorption 3Lobert

4. Gastrointestinal Pharmacology Histamine (H2) Receptor Blockers – Ex: Famotidine (Pepcid) – Ex: Ranitidine (Zantac) – Action: block the histamine activated release of gastric acids from the gastric parietal cells  reduction of acid secretions – Therapeutic Effect: control gastric acid secretion associated with dyspepsia, gastroesophageal reflux disease (GERD), peptic ulcer disease – Side Effects: rarely nausea, headache, dizziness, confusion in older adults 4Lobert

5. Gastrointestinal Pharmacology Proton Pump Inhibitors (PPI) – Ex: Omeprazole (Prilosec) – Ex: Esomeprazole (Nexium) – Action: Inhibition of the enzyme that is responsible for gastric acid secretion from the parietal cells; 90% reduction in the “acid pump” – Therapeutic Effect: reduction of gi symptoms associated GERD and peptic ulcers – Side Effects: rebound hyperacidity 5Lobert

6. Gastrointestinal Pharmacology Pharmacologic Treatment of Peptic Ulcers – Antacids Aluminum Hydroxide (Maalox) – H2 Blockers Ranitidine (Zantac) – PPI’s Omeprazole (Prilosec) – Antibacterials Clarithromycin (Biaxin), Amoxicillin (Amoxil) Metronidazole (Flagyl) Tetracycline (Achromycin) Lobert6

7. Gastrointestinal Pharmacology Antidiarrheals – Adsorbents Ex: Bismuth Salts (Pepto Bismol, Kaopectate) – Opioid Derivatives Ex: Diphenoxylate with atropine (Lomotil) Ex: Loperamide (Imodium) Lobert7

8. Gastrointestinal Pharmacology Opioid Derivatives – Ex: Diphenoxylate with Atropine (Lomotil) – Ex: Loperamide (Imodium) – Action: slows peristalsis allowing for more water reabsorption  more solid stools – Therapeutic Effect: treatment of chronic diarrhea, moderate to severe diarrhea – Note: there is no analgesic effect – Side Effects: dizziness, drowsiness 8Lobert

9. Gastrointestinal Pharmacology Adsorbents – Ex: Bismuth Salts (Pepto Bismol, Kaopectate) – Action: binds toxins that contribute to diarrhea, increases absorption of fluids and electrolytes – Therapeutic Effect: relief of mild diarrhea, prevention of “travelers diarrhea” – Side Effects: constipation, stool impaction 9Lobert

10. Gastrointestinal Pharmacology Pharmacologic Treatment of Inflammatory Bowel Disease (IBD) – Antidiarrheals – Corticosteroids – Antiinfectives – Antiinflammatories Mesalamine (Asacol, Pentasa) – Immunosuppressants Azathiprine (Imuran) – Biologic Therapies Infliximab (Remicade) Adalimumab (Humira) Lobert10

11. Gastrointestinal Pharmacology Laxative and Cathartics – Bulk Forming Ex: Psyllium Mucilloid (Metamucil) Action: absorb water adding to size of fecal mass – Osmotic Ex: Polyethylene Glycol (Miralax) Action: creates osmotic pull of fluids into gi tract – Stimulant Ex: Bisacodyl (Dulcolax) Action: irritates bowel mucosa  stimulates bm – Stool Softener Ex: Docusate (Colace) Action: causes water and fat to be absorbed in stool – Herbal Ex: Senna (Senokot) Action: irritates the bowel and increases peristalsis Lobert11

12. Gastrointestinal Pharmacology Laxatives and Cathartics – Pharmacologic Classes Bulk Forming, Osmotics, Stimulants, Softeners, Herbals Therapeutic Uses: prevention and treatment of constipation, prep for gastrointestinal testing (colonoscopies, etc) or gastrointestinal surgeries Side Effects: abdominal cramping, diarrhea, fluid and electrolyte loss, nausea Lobert12

13. Gastrointestinal Pharmacology Pharmacologic Treatment for Nausea and Vomiting: Antiemetics – Serotonin Antagonists Ex: Ondansetron (Zofran) – Antihistamines Ex: Menhydrinate (Dramamine), Meclizine (Antivert) – Anticholinergics Ex: Scopolamine (Transderm Scop) Lobert13

14. Gastrointestinal Pharmacology Antiemetics – Classes: serotonin antagonists, antihistamines, anticholinergics – Action: depress the CNS chemoreceptor zone through a variety of mechanisms – Therapeutic Effect: treatment of chemotherapeutic drug side effects, prevention of nausea, prevention of motion sickness/nausea, Lobert14