Chapter 33 Therapy of Gastrointestinal Disorders: Peptic Ulcers, GERD, and Vomiting

Process of Digestion The organs of the upper GI tract are primarily concerned with digestion and absorption of nutrients The stomach and small intestine secrete several hormones and enzymes that aid in digestion and absorption Specialized cells in the stomach produce hydrochloric acid and proteolytic enzymes which break down food particles into an absorbable form Acetylcholine, gastrin, and histamine are the major stimulators for the release of gastric juices The mucosal lining of the gi tract is lubricated with secretions of mucus and alkaline fluid that protect it from autodigestion

Peptic Ulcer Open sores that develop on the mucosal lining of the stomach and duodenum Most common cause is an infection caused by Helicobacter pylori Can also be caused by long-term use of nsaids and steroids which inhibit secretion of protective mucus and interfere with the normal production of the mucosal lining Symptoms include periodic pain (heartburn), nausea, loss of appetite, and vomiting Antibiotic treatment for H.pylori Antiulcer drug therapy Reduces gastric acidity Enhances mucosal barrier defenses Involves the use of antisecretory drugs and antacids

Gastrointestinal Esophageal Reflux Disease (GERD) Occurs due to regurgitation of digestive juices into the esophagus Happens as a result of Inappropriate relaxation of the lower esophageal sphincter Heartburn is the main symptom GERD drug therapy Suppresses acid production Prevents erosion Provides symptomatic relief

Life style modifications Diet and Lifestyle modifications have an important role in therapy for peptic ulcers and gerd Stop smoking Avoid caffeine and alcohol Reduce stress Eliminate nsaids if possible Eat smaller meals Eliminate foods that trigger/worsen symptoms Lose weight (if overweight) Elevate the head of the bed

Antisecretory Drugs: Suppression of Gastric Acid Histamine is a potent stimulator of gastric secretions Histamine receptors are found in the gastric mucosa Antihistamine (H2) receptor antagonists Reduce interaction between histamine and H2 receptors reducing acid secretions Includes Tagamet, Pepcid, zantac Used to treat gastric ulcers, gerd, and for patients who must continue nsaid use Adverse effects are few, especially during short term use Headache or constipation

Antisecretory Drugs Suppression of Gastric Acid Proton Pump Inhibitors (Prilosec, Nexium, prevacid) Directly inhibit the system that releases hydrochloric acid Clinical indications With antibiotics in treatment of ulcers associated with H. pylori Benign gastric ulcers and GERD Promote healing and prevent recurrence Adverse effects Abdominal pain, headache, diarrhea, constipation, and nausea

Acid Neutralization: Antacids Clinical indications Hyperacidity associated with peptic ulcers Upset stomach Heartburn, GERD, and acid indigestion Mechanism of action React with HCl, forming water and salts- neutralizes acidity Administered orally Short duration of action

Acid Neutralization: Antacids Special considerations Systemic absorption Most are nonsystemic Prolonged use of sodium bicarbonate may result in metabolic alkalosis adverse effects Chronic use may result in acid rebound Increased stomach pH (ALKALINE) CAUSES CELLS TO INCREASE SECRETION OF ACID LONG-TERM USE CAN ALSO INCREASE SODIUM WHICH CAN BE SIGNIFICANT FOR PATIENTS WITH HYPERTENSION OR CONGESTIVE HEART FAILURE (WATER FOLLOWS SODIUM)

Prokinetic Drugs for the Management of GERD Metoclopramide (REGLAN) Stimulates contraction of the lower esophageal sphincter BY ENHANCING THE ACTION OF ENDOGENOUS ACETYLCHOLINE PREVENTS REFLUX AND PROMOTES EMPTYING Treats meal-induced heartburn Treats chemotherapy-induced vomiting BY ANTAGONIZING DOPAMINE RECEPTORS IN THE CNS

Prokinetic Drugs for the Management of GERD Adverse effects and contraindications May produce cardiovascular effects such as palpitations and tachycardia Common adverse effects are fatigue, restlessness, nausea, and diarrhea Long-term or high-dose use increases the risk of tardive dyskinesia Contraindicated in patients in whom motility may precipitate Hemorrhage or perforation (bowel perforation or obstruction) Contraindicated in patients who are epileptic or area receiving drugs that are likely to cause extrapyramidal reactions

Management of Emesis Vomiting Natural defense mechanism that may Signals disease or organ dysfunction May be involuntary or self-induced Associated with many causes including flu, pregnancy, motion sickness, ear infections, and certain drugs Persistent vomiting results in electrolyte, fluid, and acid-base imbalances

Management of Emesis Commonly used antiemetics are antihistamines and phenothiazines that inhibit dopaminergic or cholinergic receptors Serotonin antagonists (Zofran) prevent serotonin from initiating cholinergic nerves Antihistamines (reglan) relieve vomiting and exhibit anticholinergic effects Adverse effects include dry mouth, sedation, drowsiness, diarrhea Phenothiazines (Promethazine), metoclopramide (reglan), and ondansetron (Zofran) have the potential of producing extrapyramidal reactions Safety during pregnancy has not been established