Gastrointestinal (GI) Drugs Study Guide

Peptic ulcers are open sores that form in the stomach (gastric ulcer) or duodenum (duodenal ulcer) — the first part of the small intestine. They happen when stomach acid damages the protective lining of the digestive tract.

⚠ Common Causes Helicobacter pylori (H. pylori) infection — a bacteria that weakens the stomach lining

Long-term use of NSAIDs (like ibuprofen, aspirin, naproxen) — these irritate the stomach lining

Smoking and alcohol — worsen symptoms and slow healing

Stress and spicy foods — don’t cause ulcers but can aggravate them

😣 Symptoms Burning or gnawing stomach pain, especially between meals or at night

Bloating, belching, nausea

Loss of appetite or weight loss

Vomiting blood or black, tarry stools (signs of bleeding ulcer)

Pain that wakes you up at night

🚨 Complications (If Untreated) Bleeding → can cause anemia or life-threatening blood loss

Perforation → ulcer eats through the stomach wall, leading to infection (peritonitis)

Obstruction → swelling or scarring blocks food passage

Increased risk of stomach cancer (especially with chronic H. pylori infection)

🩺 Diagnosis Breath, stool, or blood tests for H. pylori

Endoscopy to view ulcers directly

Imaging tests like CT scan or barium swallow

💊 Treatment Antibiotics to kill H. pylori

Proton pump inhibitors (PPIs) and H2 blockers to reduce acid

Antacids for quick relief

Mucosal protectants like sucralfate to coat ulcers

Lifestyle changes: avoid NSAIDs, smoking, alcohol, and irritating foods

🧠 Nursing Tips Assess pain pattern: usually after meals or at night

Check for bleeding signs: black stool, vomiting blood

Educate patient: take meds before meals, avoid NSAIDs unless prescribed

Monitor for complications: sudden sharp pain = possible perforation!

Vagus nerve stimulates release of acetylcholine (ACh).

ACh triggers histamine release.

Histamine binds to H₂ receptors in the stomach lining.

This activates acid (HCl) production → leads to ulcer formation if too much acid or weak mucosal protection.

💊 How the Meds Work Drug Class Action Tranquilizers Reduce vagal stimulation and anxiety (old-school use) Anticholinergics Block acetylcholine → ↓ acid production H₂ Blockers Block histamine2 receptors → ↓ acid PPIs Block proton pump → most powerful acid suppression Antacids Neutralize existing acid for fast relief Prostaglandin E₁ analogs Protect stomach lining and reduce acid Pepsin inhibitors Coat ulcers to protect and promote healing

🖤 Black Stool (Melena) = Upper GI Bleed "20th floor" → If bleeding happens high up (like stomach or duodenum), the blood travels far before exiting.

It gets digested along the way → turns black and tarry.

Example: Peptic ulcer, esophageal varices

🔥 Your analogy: “If you live on the 20th floor, it takes time for the trash to reach the ground — it changes along the way.”

❤ Bright Red Blood (Hematochezia) = Lower GI Bleed "1st floor" → Bleeding near the exit (colon, rectum) comes out quickly and fresh.

No time for digestion → stays red.

Example: Hemorrhoids, diverticulosis, colon cancer

🔥 Your analogy: “If you live on the 1st floor, you throw the trash and it’s out right away — no change.”

This drug can affect the absorption of other drugs: Sucralfate decreases the absorption of phenytoin. The nurse should instruct the client to allow at least 2 hr between taking the two medications and should monitor the client's phenytoin levels.

Anticholinergics like propantheline are not typically the first line for acid reflux because they reduce motility and slow down the gut. They’re more often used if you need to reduce gastric spasms or if there’s a need to cut down on acid secretion in a different way. But because they slow everything down, they’re not the go-to for just straightforward reflux management. You might see them more in cases where you need to calm the gut or reduce cramping rather than just for reflux alone.

Ondansetron: Infuse the medication 30 min prior to chemotherapy is correct. Infuse the medication slowly over 15 min is correct. Repeat the dose 4 hr after chemotherapy is correct. 

Dizziness and lightheadedness are the most common adverse effects of ondansetron.

Senna is like Paris river Sena, river moves, sena increases motility. Senna can lead to brown redish urine, cause the effel tower is rusty and Paris smeels like Pee.

Docusate sounds like Duck, duck poop is soft, and u drink Duck soup after MI or Suregery to feel better, that’s whay is used after surgery to prevent constipation and straining.

Chlorida Ch Ac, sounds like Anus, and Lubiprostone souns like lubricant, so you know…. Side effect then are headache (cause u don’t want to do it), nausea, and diarreah. And Sinces is a lubricant it increases fluid, and since is penetration that means motility.

Diphenoxylate is an opioid, which can cause the severe complication of toxic megacolon in clients who have inflammatory bowel disease. The nurse should have the client monitor the consistency and frequency of stools throughout therapy.

When analyzing cues, the nurse should identify that sulfasalazine should be administered with caution to a client who has a history of asthma, renal impairment, and anemia because sulfasalazine may cause these conditions to worsen. The client has a history of asthma, their BUN and creatinine are elevated, and their Hgb and Hct are below the expected ranges for a male client.

Skin integrity is correct. Sulfasalazine can cause a skin rash, so the nurse should check the client's skin for rashes. The medication can also cause nausea. If the client reports nausea, the nurse should suggest taking the medication with food or water.

Temperature is correct. Sulfasalazine can cause a fever, so the nurse should check the client's temperature and treat fever with an antipyretic. CBC is correct. Sulfasalazine can cause hematologic disorders, such as agranulocytosis and hemolytic and macrocytic anemia. The nurse should check the client's CBC periodically during therapy and tell the client to report sore throat or fatigue.

Clients who take alosetron, a serotonin 5-HT3 receptor antagonist, can develop severe constipation that can lead to impaction, bowel obstruction, perforation, and potentially fatal ischemic colitis. Because of these risks, nurses must inform clients of the benefits and risks of the medication therapy, and clients must sign a treatment agreement. Alosetron, a serotonin 5-HT3 receptor antagonist, can cause ischemic colitis. The nurse should tell the client to report abdominal pain, bloody diarrhea, or rectal bleeding, and to stop taking the medication if these manifestations occur.

Alosetron is approved only to be prescribed to clients who were assigned female at birth who have IBS-D lasting 6 months or longer and has not been controlled by conventional treatment.