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

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

Objective 5: describe the pain reducing effects of antacids

Decreased pain 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

Objective 7: differentiate between the various antacids

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 8: describe the nursing implications associated with antacid therapy

What are the assessments and interventions the nurse would do for a client taking an antacid?

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

What would you see with anticholinergics? 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?

Which clients should not use 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

Used for GERD, duodenal ulcers, Zollinger-Ellison syndrome 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

SE: diarrhea, HA, muscle pain and fatigue If rash: call MD

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?

laxatives 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 Caution: surgical abdomen; appendicitis; N/V; fecal impaction; intestinal obstruction; undiagnosed abdominal pain Contraindicated: hypersensitivity

Groups of Laxatives Bulk-forming Emollient Hyperosmotic Saline Stimulant

Mechanism of action Best for long term use Bulk-forming: natural fiber-like Absorb water Distends bowel Initiates reflex bowel activity Best for long term use

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

Lubricates fecal material & intestinal wall 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

Increases bulk Softens stool Stimulant laxatives stimulate nerves Increases peristalsis Increase fluid in colon Increases bulk Softens stool

Drug effects Few systemic effects Therapeutic Uses Primary site of action the gut Therapeutic Uses Common constipation Bowel preparation pre-op, diagnostic tests

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

Interactions 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

Antidiarrheals Groups based on mechanism of action Adsorbents Antimotility Bacterial replacement Antisecretory Enzymes

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

Anticholenergics Decrease: peristalsis, muscle tone Use with adsorbents, opiates Examples: Atropine Hyoscyamine Hyosine

Opiates Decrease bowel motility Reduce pain Increased absorption of water & elytes (absorption time)

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

Interactions 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

Objective 22: describe the nursing implications associated with antidiarrheal agents

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 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

Phenothiazines mostly used Reglan popular

Serotonin Antagonists: chemotherapy, radiation, post op Block serotonin receptors in the CTZ and GI tract Drugs include Dolasetron (Anzemet); granisetron (Kytril) and ondansetron (Zofran)

Often for motion sickness; may see for clients on chemotherapy 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

Corticosteroids Sometimes see Decadron Don’t know its action

Do cause mind altering effects Can be abused Cannaboinoids 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)

Objective 26: explain the use of emetics

Fresh supplies are needed as the drug will expire 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?

Objective 28: demonstrate the ability to calculate drug dosages