MODULE 12

Module 12: Gastrointestinal Tract Medications

Structure & Function Review

• Accessory Organs of the Digestive System:

  • Mouth

  • Salivary Glands

  • Liver

  • Gallbladder

  • Appendix

  • Esophagus

  • Stomach

  • Pancreas

  • Large Intestine

  • Small Intestine

  • Rectum

  • Anus

Common Gastrointestinal Disorders

• Peptic Ulcer Disease

• GERD (Gastroesophageal Reflux Disease)

• Gastrointestinal Disorders

• Nausea & Vomiting

• Diarrhea

• Constipation

• IBD (Irritable Bowel Disease)

Peptic Ulcer Disease

• Definition:

  • Erosion of the mucosal layer of the stomach or duodenum

• Causes:

  • Helicobacter pylori (bacteria)

  • NSAID use

GERD (Gastroesophageal Reflux Disease)

• Definition:

  • Weakening or relaxation of the esophageal sphincter

• Signs & Symptoms:

  • Heartburn

  • Dysphagia (difficulty swallowing)

  • Dyspepsia (indigestion)

  • Chest pain

  • Nausea

  • Belching

Pharmacotherapy for Peptic Ulcers & GERD

• Medications Used:

  • H2-receptor antagonists (Histamine2-blockers)

  • Proton Pump Inhibitors (PPIs)

  • OTC Antacids

  • Antibiotics (discussed in the next module)

H2-Receptor Antagonists

• Mechanism of Action:

  • Inhibit histamine at H2-receptor sites in parietal cells, decreasing gastric acid secretions

• Indications:

  • Treat symptoms of Peptic Ulcer Disease and GERD

• Long-term Use Implication:

  • May lead to Vitamin B12 deficiency

• Example:

  • Ranitidine (Zantac)

Proton Pump Inhibitors (PPIs)

• Mechanism of Action:

  • Reduce acid secretion in the stomach

• Comparative Efficacy:

  • Greater efficacy than H2 receptor antagonists

• Durability:

  • Longer duration of action

• Administration Considerations:

  • Take 30 minutes before meals (i.e., breakfast)

• Side/Adverse Effects:

  • Diarrhea, headache, dizziness

  • Potential for gastric cancer with long-term use

Nursing Considerations for H2 Blockers and PPIs

• Medication Interactions:

  • May affect absorption of other medications; identify which medications are impacted

• Timing of Administration:

  • Importance of taking medications 30 minutes prior to eating

• Non-pharmacological Ways to Reduce GERD:

Antacids

• Classification:

  • Over the counter (OTC) medications

• Mechanism of Action:

  • Alkaline substances that neutralize gastric acid

• Considerations:

  • Affect absorption of many drugs

Nursing Considerations for Antacids

• Adverse Effects:

  • Constipation (calcium and aluminum-based antacids)

  • Diarrhea (magnesium-based antacids)

  • Electrolyte imbalances

• Administration Guidance:

  • Take at least 2 hours before or 2 hours after other oral medications

  • Patients with renal failure should avoid magnesium-based antacids

Nausea & Vomiting

• Causes of Vomiting:

  • Various causes — further details provided in specific treatment discussions

• Non-pharmacological Methods to Control Vomiting:

• Inducing Vomiting:

  • Evaluation of when to induce vomiting and associated safety considerations

• Serious Consequences:

  • Dehydration, electrolyte imbalances

Mechanism of Vomiting

• Controlled by the vomiting center located in the medulla

  • Receives signals from the digestive tract, inner ear, and cerebral cortex

Anti-Emetics

• Definition:

  • Emesis refers to vomit

• Therapeutic Use:

  • Decrease nausea and reduce vomiting

• Mechanism of Action:

  • Dependent on the chemical classification of the antiemetic

• Types of Anti-emetics:

  • Anticholinergics and Antihistamines

  • Dopamine Antagonists

  • Serotonin (5-HT3) Receptor Antagonists

Anticholinergic and Antihistamines

• Use Cases:

  • Effective for treating simple nausea; some versions available OTC

• Mechanism of Action:

  • Work by inhibiting vestibular stimulation in the middle ear

• Applications:

  • Effective for nausea, vomiting, and motion sickness

• Examples:

  • Dimenhydrinate (Gravol)

  • Meclizine (Bonamine)

Nursing Considerations for Antihistamines & Anticholinergics

• Side Effects to Monitor:

• Patient Teaching Points:

• Case Scenarios:

  • Inquiry regarding effects of administering specific medications under certain conditions like constipation

Dopamine Antagonists

• Mechanism of Action:

  • Block dopamine II receptor sites in the brain responsible for inducing vomiting

• Examples:

  • Metoclopramide (Maxeran)

  • Increases peristalsis and is best given IV for severe nausea and vomiting

Serotonin Receptor Blockers

• Example:

  • Ondansetron

• Usage Limitation:

  • Typically used for nausea and vomiting associated with antineoplastic therapy; prescription only and expensive

Lower GI Tract Agents

• Categories of Agents:

  • Anti-inflammatory

  • Laxatives

  • Antidiarrheals

  • Medications for IBD

Inflammatory Bowel Disease (IBD)

• Types:

  • Crohn’s Disease

  • Lesions in the digestive tract

• Etiology:

  • Unknown, suspected autoimmune

• Symptoms:

  • Abdominal cramping and frequent bowel movements

IBD Medications

• Categories of Medications:

  • Aminosalicylates

  • Antibiotics

  • Corticosteroids

  • Immunomodulators

  • Biologic therapies

Constipation

• Factors Contributing to Constipation:

  • Various biological, psychological, and social factors

• Symptoms Associated with Constipation:

• Non-pharmacological Methods to Alleviate Constipation:

Pharmacotherapy of Constipation

• Laxatives Classification:

  • Prophylactic

  • Treatment drugs that promote evacuation of the large bowel

  • Types:

  • Osmotic laxatives

  • Bulk-forming laxatives

  • Emollients (stool softeners)

  • Stimulant laxatives

Osmotic Laxatives (Hyperosmotic Agents)

• Mechanism of Action:

  • Not absorbed in the intestine; pull water into feces from surrounding tissues, softening the stools and facilitating peristalsis

• Risk Considerations:

  • Normal renal function required; can cause electrolyte imbalances

• Example:

  • Lactulose, which also reduces ammonia levels in the bloodstream

Bulk-Forming Laxatives

• Mechanism of Action:

  • Absorb liquid in the intestines, swell to form soft bulky stool to stimulate bowel movements

• Example:

  • Psyllium (Metamucil)

Emollients (Stool Softeners)

• Mechanism of Action:

  • Encourage bowel movements by helping liquids mix in the stool, acting as a lubricant to prevent dry hard stool

• Example:

  • Docusate sodium (Colace)

Stimulant Laxatives

• Mechanism of Action:

  • Trigger contractions in intestinal muscles (promote peristalsis) by irritating sensory nerve endings; cramping is a common side effect

• Additional Actions:

  • Increase water in the stool via absorption inhibition or secretion stimulation

• Example:

  • Bisacodyl (Dulcolax)

Laxatives: Adverse Effects

• Potential Adverse Effects:

  • Diarrhea

  • Electrolyte imbalances

  • Dehydration

  • Abdominal pain

  • Decreased absorption of other medications

Diarrhea

• Causes of Diarrhea:

  • Various etiologies — to be discussed further in the treatment section

• Life-Threatening Consideration:

  • Diarrhea can be life-threatening in certain populations, such as the elderly and infants

• Non-pharmacological Treatment Methods:

Antidiarrheals

• Mechanism of Action:

  • Act systemically or locally to ameliorate diarrhea; classifications include opioid-related drugs and absorbents

Antidiarrheal Medications - Opiates

• Mechanism of Action:

  • Systematically depress CNS, decreasing peristalsis; allows for more time for water and salts to be reabsorbed

• Example:

  • Loperamide (Imodium)

Antidiarrheal Medications - Absorbents

• Mechanism of Action:

  • Work by coating the wall of the GI tract and absorbing/inhibiting activity of bacteria or toxins

• Example:

  • Bismuth subsalicylate (Pepto-Bismol)

Case Study: Mrs. Sadie

• Patient Information:

  • An 85-year-old female presenting with abdominal pain, vomiting, and no bowel movement for 4 days despite taking Metamucil for 2 days.

Assessment – Mrs. Sadie

• Physical Findings:

  • Abdomen distended, painful on palpation, dry mucous membranes, no flatus

• Vital Signs:

  • T 36.7, HR 110, BP 99/57, RR 18, O2 sat 90% on RA

• Medications:

  • Tylenol #3 (for arthritis) and Lipitor for high cholesterol

• Medical History:

  • Arthritis, high cholesterol, history of appendectomy, and gallbladder removal

Considerations for Assessment

• Risk Factors for Constipation:

• Risk Factors for Bowel Obstruction:

• Evaluation of Vital Signs:

Patient Responses During Treatment

• Patient Inquiry:

  • Patient requested a stronger laxative to address her issues at home; consider the best response and care approach.

Follow-Up Case Assessment

• Outcome:

  • After CT scan, diagnosed with constipation, sent home with a fleet enema

• Medication Classification Inquiry:

  • Identify the type of laxative that a fleet enema represents.