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Gastrointestinal Drugs. Pharmacology I: NURS 1950. Objective 1: list the components of gastric juice that contribute to the pain associated with peptic ulcers Objective 2: describe the physiology of gastric secretions. Objective 3: list drugs considered to be ulcerogenic.

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gastrointestinal drugs

Gastrointestinal Drugs

Pharmacology I: NURS 1950


Objective 1: list the components of gastric juice that contribute to the pain associated with peptic ulcers

  • Objective 2: describe the physiology of gastric secretions

Objective 4: explain the actions of the antiulcer drugs

    • Decrease acidity
    • Block histamine receptors
    • Gastrointestinal prostaglandins

Gastric acid pump inhibitors

  • Coating agents
  • Prokinetic agents
  • Antispasmodic agents

Raise the pH of gastric contents

    • Higher pH, less acidity
      • Decreased pain

Objective 6: identify the features of an ideal antacid

    • Cheap
    • Effective
    • No constipation or diarrhea
    • No systemic effects
    • No rebound acidity

Riopan, Maalox, Mylanta II, low sodium

  • Calcium carbonate, Aluminum hydroxide: constipation
  • Magnesium: diarrhea, electrolyte imbalance
  • Calcium carbonate & sodium bicarbonate: rebound acidity

Simethicone: defoaming agent

Alginic acid: highly viscous solution—sodium alginate


Objective 9: state the mechanism of action of anticholinergic and antispasmodic agents


Anticholinergics and antispasmodics the same

    • Drugs include belladonna, probanthine, bentyl
    • Used for spastic conditions of GI tract, peptic ulcers and irritable bowel syndrome
    • Block parasympathetic nervous system
      • Activity is systemic
      • What would you see with anticholinergics?

Objective 10: identify appropriate nursing actions relative to caring for clients receiving antispasmodic drugs


Assess: mental status, teach about orthostatic hypotension

  • In the elderly: increased constipation
  • If arrhythmia or palpitations: stop the drug, call the physician

Objective 11: describe the effects and uses of H2 receptor antagonists, and proton pump inhibitors


H2 receptor antagonists

    • Block histamine 2 receptors
    • Raises pH of gastric contents
      • Used for GERD, duodenal ulcers, Zollinger-Ellison syndrome
      • Used to prevent or treat stress ulcers

Drugs include

    • Cimetidine (Tagamet)
    • Famotidine (Pepcid)
    • Nizatidine (Axid)
    • Rantidine (Zantac)

Drugs can cause

    • Dizziness, HA, diarrhea, constipation
    • If confusion, disorientation, hallucination, see MD
    • Can cause gynecomastia, hepatotoxicity

Proton pump inhibitors

    • Inhibit gastric acid pump
    • Treat: severe esophagitis, GERD, gastric and duodenal ulcers, Zollinger-Ellison syndrome
    • Can be used with antibiotics for H pylori

Drugs include

    • Esomeprazole (Nexium)
    • Lansoprazole (Prevacid)
    • Omeprazole (Prilosec)
    • Pantoprazole (Protonix)
    • Rabeprazole (Aciphex)

Objective 12: Explain the nursing interventions associated with H2 receptor antagonists and proton pump inhibitors


Objective 13: identify causes of constipation

  • Objective 14: explain the uses of laxatives and cathartics
  • Objective 16: describe the actions of the types of laxatives
  • Objective 17: identify laxatives according to type

Causes of constipation

    • What are some things or conditions that can cause constipation?
  • Act three ways
    • Affect fecal consistency
    • Increase fecal movement
    • Remove stool from rectum

Laxatives OTC; misused

    • Dependence
    • Damage bowel
    • Cause problems in bowel
contraindications precautions
Contraindications, Precautions
  • Caution: surgical abdomen; appendicitis; N/V; fecal impaction; intestinal obstruction; undiagnosed abdominal pain
  • Contraindicated: hypersensitivity
groups of laxatives
Groups of Laxatives
  • Bulk-forming
  • Emollient
  • Hyperosmotic
  • Saline
  • Stimulant
mechanism of action
Mechanism of action
  • Bulk-forming: natural fiber-like
    • Absorb water
    • Distends bowel
    • Initiates reflex bowel activity
      • Best for long term use

Emollient laxatives

    • Stool softener (Docusate salts)
      • Lowers surface tension
        • Allows more fat & water to be absorbed
          • When should these be used?

Lubricant laxative (mineral oil)

    • Lubricates fecal material & intestinal wall
      • Prevents H20 from leaking out of gut
        • Stool expands & softens

The emollients and lubricants do not seem to increase peristalsis

    • Oils a problem in constantly recumbent clients

Hyperosmotic increase water content in large intestine

    • Distends bowel
    • Increases peristalsis
    • Evacuates the bowel
    • Non-absorbable ion exchange
    • Used before diagnostic tests

Saline laxatives increase osmotic pressure in small intestine

    • Inhibit absorption of water & elytes
    • Increase amount of water & elytes

Results: watery stool

  • Increased distention of bowel
  • Promotes peristalsis & evacuation
    • Example: citrate of magnesia

Stimulant laxatives stimulate nerves

    • Increases peristalsis
    • Increase fluid in colon
      • Increases bulk
      • Softens stool
drug effects
Drug effects
  • Few systemic effects
    • Primary site of action the gut
  • Therapeutic Uses
    • Common constipation
    • Bowel preparation pre-op, diagnostic tests
side effects adverse effects
Side Effects/Adverse Effects
  • Bulk forming: impaction above strictures, fluid overload, electrolyte imbalance, gas
  • Emollient: skin rash, decreased absorption vitamins, lipid pneumonia, elyte imbalance
  • Hyperosmotic: abdominal bloating, rectal irritation, elyte imbalance

Saline: magnesium toxicity, elyte imbalance, diarrhea, increased thirst

  • Stimulant: nutrient malabsorption, gastric irritation, elyte imbalance, discolored urine, rectal irritation
  • Bulk-forming: interfere with absorption antibiotics, digoxin, salicylates, oral anticoagulants
  • Mineral oil: decrease absorption fat soluble vitamins
  • Hyperosmotic: increased CNS depression with barbiturates, general anesthetics, opioids, antipsychotics

Oral antibiotics decrease effect of lactulose

  • Stimulants: decrease absorption antibiotics, digoxin, tetracycline, oral anticoagulants

Objective 15: identify features of an ideal laxative and cathartic

    • What do you think makes an ideal laxative?

Objective 18: describe the major nursing implications associated with the administration of laxatives


Assess: drugs client takes including OTC and herbs

  • Assess bowel elimination pattern
  • Assess diet and fluid intake
  • Assess activity and exercise
  • Assess for travel, dehydration
  • Assess for any past GI problems

Objective 19: identify causes of diarrhea

    • What things, conditions can cause diarrhea?

Objective 20: describe the uses of antidiarrheal agents

  • Objective 21: identify the antidiarrheal agents

Antidiarrheal drugs: local or systemic action

    • Local: adsorb water to cause a formed stool
    • Systemic: act on autonomic nervous system to decrease peristalsis
  • Groups based on mechanism of action
    • Adsorbents
    • Antimotility
    • Bacterial replacement
    • Antisecretory
    • Enzymes
mechanism of action1
Mechanism of action
  • Treat underlying cause
  • Adsorbents: coat walls of GI tract; bind causative bacteria, toxin
    • Bismuth subsalicylate (Pepto-Bismol)
    • Attapulgite (Kaopectate)
    • Aluminum hydroxide (AlternaGel, Maalox)
    • Kaolin-pectin
  • Decrease: peristalsis, muscle tone
  • Use with adsorbents, opiates
  • Examples:
    • Atropine
    • Hyoscyamine
    • Hyosine
  • Decrease bowel motility
  • Reduce pain
  • Increased absorption of water & elytes (absorption time)
drug effects1
Drug Effects
  • Adsorbents: bismuth subsalicylate: form of ASA
  • Activated charcoal
  • Side Effects
    • Adsorbents: can increase bleeding time, dark stools, tinnitus, metallic taste, blue gums
    • Anticholinergics: urinary retention, impotence, anxiety, brady or tachy-cardia, blurred vision, photophobia
  • Adsorbents: decrease digoxin, clindamycin, oral hypoglycemics. Methotrexate-toxicity
  • Anticholinergics: decreased effect with antacids. Increased anticholinergic effect with tricyclic antidepressants, MAOIs, amantadine & antihistamines

Opiates: additive CNS depression-alcohol, narcotics, sedative-hypnotics, antipsychotics, skeletal muscle relaxants

  • Pepto + oral anticoagulants

Assess for cause of diarrhea

    • Medications
    • Infections
    • Diet
    • Lactulose intolerance
    • Emotional stress
    • Hyperthyroidism
    • Inflammation of gut
    • Surgical bypass of gut

Objective 23: discuss the pathophysiology of nausea and vomiting

    • Nausea: sensation of abdominal discomfort that is intermittently accompanied by the desire to vomit
    • Vomiting: the forceful expulsion of gastric contents up the esophagus and out of the mouth

Objective 24: identify antiemetic drugs and their classification

    • Dopamine antagonists
    • Serotonin antagonists
    • Anticholinergics
    • Corticosteroids
    • Benzodiazepines
    • Cannaboinoids

Objective 25: identify the mechanism of action, indications for use and desired effects of antiemetic drugs

dopamine antagonists
Dopamine antagonists
  • Phenothiazines, butyrophenones (Haldol) and metoclopramide (Reglan)
    • Phenothiazines include Thorazine and Compazine
      • Drugs act to inhibit dopamine receptors that are part of the pathway to the vomiting center.
        • Also block other dopamine receptors in the brain
          • Can cause EPS

Serotonin Antagonists: chemotherapy, radiation, post op

  • Block serotonin receptors in the CTZ and GI tract
  • Drugs include
    • Dolasetron (Anzemet); granisetron (Kytril) and ondansetron (Zofran)

Anticholinergics: counterbalance the amount of acetylcholine at the CTZ

  • Often for motion sickness; may see for clients on chemotherapy
  • Drug examples
    • Cyclizene (Marezine), dimenhydrate (Dramamine), meclizene (Antivert), scopolamine


    • Sometimes see Decadron
    • Don’t know its action


    • Active ingredient THC from marijuana
    • Inhibit various pathways to the CTZ
    • Drugs include: dronabenol (Marinol)
      • Do cause mind altering effects
      • Can be abused

Benzodiazepines: various activities such as sedation, depression of vomiting center, can cause amnesia

    • Examples: diazepam, lorazepam and midazolam

New for chemo clients

    • Neurokinin receptor antagonist
      • Aprepitant (Emend)

Emetics are used when the stomach needs to be emptied

    • Use after overdose
    • Example: syrup of Ipecac: NO LONGER used for kids
      • Fresh supplies are needed as the drug will expire

Objective 27: Describe the nursing process related to the administration of emetics/antiemetics

    • What assessments would you make?
    • What interventions would you initiate?