GI Pharmacology and Oral Health Flashcards

Functional Principles of the Gastrointestinal (GI) System

• One-Way Path: The GI tract is essentially a one-way system. Food must enter through the mouth, travel through the body, and exit at the rectal opening. Clinical issues arise when GI content travels backward (reflux) or is obstructed.
• Structural Divisions: In Medical-Surgical nursing, the GI tract is categorized into the upper system, lower system, and accessory organs.
• Acidic Environment: The stomach contains hydrochloric acid ($HCl$), which is potent enough to melt/break down food substances.
• Diagnostic pH Levels:
  • When verifying NG tube patency, the $pH$ of gastric aspirate should be less than $4$.
  • A $pH$ level of $5$ or higher suggests the tube may be in the lungs rather than the gastrointestinal tract.
  • For comparison, the normal human blood $pH$ range is $7.35 \text{ -- } 7.45$.

Oral Health and Hygiene Pharmacology

• Cold Sores:
  • Caused by Herpes Simplex Virus Type 1 ($HSV-1$).
  • Pathogen Type: Viral.
  • Treatment: Antiviral medications, which typically end in the suffix "-vir" (e.g., Acyclovir).
• Dentifrices:
  • Common household products like toothpaste and floss.
  • Active Ingredient: Usually contain Fluoride ($F^-$).
  • Primary Action: Reduce plaque formation, remove dirt/plaque buildup, and prevent cavities. They also provide comfort through a refreshing taste.
  • Side Effects: Primarily mechanical issues (e.g., brushing too hard) rather than physiological adverse effects.
• Mouthwashes:
  • Mechanism: Contain fluoride for cavity prevention and oral health.
  • Nursing Considerations for Anticholinergics: Anticholinergic drugs cause dry mouth (xerostomia). Nurses should provide mouthwashes that have low or zero alcohol content, as alcohol dries out mucous membranes faster and irritates stomatitis.
  • Halitosis (Bad Breath): Can be caused by cavities, oral infections, or throat issues like pharyngitis or laryngitis. Mouthwashes manage the symptom, but the underlying cause (e.g., dental decay) must be treated for a permanent fix.
• The Flossing Controversy (Cardiology vs. Dentistry):
  • Cardiologist Perspective: They worry about frequent flossing causing trauma and bleeding in the gums. Bleeding creates a port of entry for pathogens to enter the bloodstream (systemic entry), which can lead to Rheumatic Heart Disease or Endocarditis (inflammation of the heart muscle layers).
  • Prophylactic Use: Patients at risk for cardiac infections may be given a one-time prophylactic antibiotic dose before dental cleanings.

Gastroesophageal Reflux Disease (GERD) and Peptic Ulcer Disease (PUD)

• GERD Pathophysiology:
  • Occurs when the Lower Esophageal Sphincter ($LES$) fails to stay closed or when gastric acid levels are excessively high.
  • The esophageal walls are made of different cells than the stomach and are not designed for acid exposure. Repeated exposure leads to "heartburn."
• PUD Pathophysiology:
  • Described as an erosion or "hole" in the gastric wall, similar to a stage two bedsore on the skin.
  • Causes: $H. pylori$ bacteria, excessive use of NSAIDs/Aspirin, smoking (nicotine), and alcohol (especially high-proof spirits).
• Complications:
  • Melena: Black, tarry stools caused by the digestion of blood from a gastric ulcer.
  • Perforation: A rupture in the stomach wall allowing GI content to enter the peritoneal space.
  • Peritonitis: Infection of the peritoneum.
  • Sepsis: A massive systemic infection resulting from peritonitis, which can be fatal.
• Lifestyle Factors: Stress, anxiety, and anger (sympathetic nervous system activation) increase hydrochloric acid levels, exacerbating both GERD and PUD.

Acid-Lowering and Protective Medications

• Antacids:
  • Function: Neutralize existing stomach acid to lower acidity levels.
  • Agents: Calcium carbonate (Tums), Aluminum hydroxide, Magnesium oxide, and Sodium bicarbonate.
  • Simethicone (Gas-X): Specifically treats gas ($H_2$ gas) buildup that causes bloating and belching.
  • Side Effects: Constipation (Calcium/Aluminum); Diarrhea (Magnesium).
  • Nursing Alert: Avoid Sodium Bicarbonate in hypertensive patients (high sodium load). Avoid Magnesium for renal failure patients (inability to filter electrolytes).
  • Drug Interactions: Give antacids $1\,hour$ before or $1\,hour$ after other medications (like Atenolol) to prevent neutralization of the other drug.
• H2 Receptor Blockers:
  • Suffix: "-tidine" (e.g., Cimetidine, Ranitidine, Famotidine).
  • Function: Block histamine 2 receptors to decrease acid secretion.
  • Timing: Taken before meals ("Before I dine").
  • Side Effects: Dizziness, headache, somnolence, confusion, and hallucinations. These are hepatotoxic and can cause Gynecomastia in males.
• Proton Pump Inhibitors (PPIs):
  • Suffix: "-prazole" (e.g., Omeprazole/Prilosec, Pantoprazole).
  • Function: Block the hydrogen ion pump to reduce acid production.
  • Long-term Risk: Prolonged use leads to porous, brittle bones and increased risk for fractures (especially in post-menopausal females due to estrogen depletion).
• Protective Agents:
  • Gastrointestinal Prostaglandins (Misoprostol/Cytotec): Inhibits acid and pepsin to protect the lining. Note: Used in OB for miscarriages and uterine contractions; strictly regulated.
  • Coating Agents (Sucralfate/Carafate): Forms a protective gel-like substance that adheres to the ulcer crater to shield it from acid. It has no effect on acid production. Side effect: Constipation.
• Prokinetics:
  • Agent: Metoclopramide (Reglan).
  • Function: Increases $LES$ pressure to reduce reflux and improves peristalsis (gastric emptying).
  • Side Effects: Drowsiness and Extrapyramidal Symptoms ($EPS$), such as muscle rigidity and tremors.

Antiemetic Pharmacology (Nausea and Vomiting)

• Dopamine Antagonists:
  • Agents: Metoclopramide, Promethazine.
  • Action: Inhibit dopamine receptors in the vomiting center.
  • Risk: Significant sedation and decreased Level of Consciousness ($LOC$). Implement safety/fall precautions.
• Serotonin Antagonists:
  • Agent: Ondansetron (Zofran).
  • Usage: Blocks stimulation of the brain's vomiting center. Common side effects: Sedation and diarrhea.
• Anticholinergic Agents:
  • Agent: Scopolamine (available as patches placed behind the ears).
  • Usage: Excellent for motion sickness (seasickness) or post-anesthesia vomiting.
  • Side Effects: Sedation and classic anticholinergic effects (dry mouth, blurred vision, urinary retention, and constipation).
• Corticosteroids:
  • Agents: Ending in "-one" (e.g., Dexamethasone).
  • Side Effects: Hyperglycemia, weight gain/water retention, and immunocompromised status.
  • Rule: Must be tapered off; never stop abruptly.
• Benzodiazepines:
  • Agents: Ending in "-pam" (e.g., Lorazepam, Diazepam).
  • Action: Depress the vomiting center.
  • Nursing Alert: Like opioids, they decrease Respiratory Rate and $LOC$. Never combine with alcohol.
• Cannabinoids & Neurokinin-1 Antagonists:
  • Cannabinoids (e.g., Dronabinol) can cause dysphoric effects/hallucinations.
  • Aprepitant (Neurokinin-1 Antagonist) blocks the vomiting center in the brain; monitor for constipation.

Questions & Discussion

• Q: Does a stomach ulcer cause bad breath?
• A: Yes, specifically when the patient belches, the smell of the ulcer/stomach contents can be detected.
• Q: Can we take pain meds and anti-vomiting meds at the same time?
• A: Critical thinking is required. Combining opioids (for pain) and benzodiazepines (for vomiting) increases the risk of life-threatening respiratory depression and heavily sedated $LOC$. Nurses must coordinate the timing of these medications safely.