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Gastrointestinal Drugs
Pharmacology : NURS 1950
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Objective 1: list the components of gastric juice that contribute to the pain associated with peptic ulcers
◦ HCL, Pepsin, gastrin, lipase and histamine
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Chief cells◦ Secrete pepsinogen
Parietal cells◦ Stimulated by acetylcholine to produce HCL and
gastrin◦ Intrinsic factor
Mucous cells◦ Coats stomach wall
Obj. 2 describe path of gastric secrections
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Objective 3: list drugs considered to be ulcerogenic
Smoking NSAIDS Corticosteroids ASA
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Objective 4: explain the actions of the antiulcer drugs
◦ Decrease acidity
◦ Block histamine receptors
◦ Gastrointestinal prostaglandins
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◦ Gastric acid pump inhibitors
◦ Coating agents
◦ Prokinetic agents
◦ Antispasmodic agents
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Raise the pH of gastric contents◦ Higher pH, less acidity Decreased pain
Objective 5: describe the pain reducing effects of antacid
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◦ Cheap◦ Effective◦ No constipation or diarrhea◦ No systemic effects◦ No rebound acidity
Objective 6: identify the features of an ideal antacid
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Objective 7: differentiate between the various antacids
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Riopan, Maalox, Mylanta II,◦ low sodium
Calcium carbonate, Aluminum hydroxide: constipation
Magnesium: ◦ diarrhea, electrolyte imbalance
Calcium carbonate & sodium bicarbonate: rebound acidity
Simethicone: ◦ defoaming agentAlginic acid: highly viscous solution—sodium alginate
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What are the assessments and interventions the nurse would do for a client taking an antacid? ◦ Renal◦ GI◦ Schedule of meds
Objective 8: describe the nursing implications associated with antacid therapy
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Objective 9: state the mechanism of action of anticholinergic and antispasmodic agents
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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?
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◦ Which clients should not use anticholinergics?
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Assess: mental status, teach about orthostatic hypotension
In the elderly: increased constipation If arrhythmia or palpitations: stop the drug,
call the physician
Objective 10: identify appropriate nursing actions relative to caring for clients receiving antispasmodic drugs
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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
Objective 11: describe the effects and uses of H2 receptor antagonists, and proton pump inhibitors
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Drugs include◦ Cimetidine (Tagamet)◦ Famotidine (Pepcid)◦ Nizatidine (Axid)◦ Rantidine (Zantac)
Prototype
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Drugs can cause◦ Dizziness, HA, diarrhea, constipation◦ If confusion, disorientation, hallucination, see MD◦ Can cause gynecomastia, hepatotoxicity
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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
◦ S/E: diarrhea, HA, muscle pain and fatigue◦ If rash: call MD
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Drugs include◦ Esomeprazole (Nexium)◦ Lansoprazole (Prevacid)◦ Omeprazole (Prilosec)
prototype◦ Pantoprazole (Protonix)◦ Rabeprazole (Aciphex)
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Consult with MD Avoid ETOH Correct timing No smoking Immediately report blood
Objective 12: Explain the nursing interventions associated with H2 receptor antagonists and proton pump inhibitors
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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
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Causes of constipation◦ What are some things or conditions that can
cause constipation?
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Act three ways◦ Affect fecal consistency◦ Increase fecal movement◦ Remove stool from rectum
laxatives
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Laxatives OTC; misused◦ Dependence◦ Damage bowel◦ Cause problems in bowel
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Caution: surgical abdomen; appendicitis; N/V; fecal impaction; intestinal obstruction; undiagnosed abdominal pain
Contraindicated: hypersensitivity
Contraindications, Precautions
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Bulk-forming Emollient Hyperosmotic Saline Stimulant
Groups of Laxatives
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Bulk-forming: natural fiber-like◦ Absorb water ◦ Distends bowel◦ Initiates reflex bowel activity Best for long term use
Mechanism of action
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Emollient laxatives◦ Stool softener (Docusate salts) Lowers surface tension
Allows more fat & water to be absorbed When should these be used?
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◦ Lubricant laxative (mineral oil) Lubricates fecal material & intestinal
wall Prevents H20 from leaking out of gut Stool expands & softens
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The emollients and lubricants do not seem to increase peristalsis◦ Oils a problem in constantly recumbent clients
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Hyperosmotic increase water content in large intestine◦ Distends bowel◦ Increases peristalsis◦ Evacuates the bowel◦ Non-absorbable ion exchange◦ Used before diagnostic tests
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Saline laxatives increase osmotic pressure in small intestine◦ Inhibit absorption of water & elytes◦ Increase amount of water & elytes
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Results: watery stool Increased distention of bowel Promotes peristalsis & evacuation
Example: citrate of magnesia
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Stimulant laxatives stimulate nerves◦ Increases peristalsis◦ Increase fluid in colon Increases bulk Softens stool
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Few systemic effects◦ Primary site of action the gut
Therapeutic Uses◦ Common constipation◦ Bowel preparation pre-op, diagnostic tests
Drug effects
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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
Side Effects/Adverse Effects
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Saline: magnesium toxicity, elyte imbalance, diarrhea, increased thirst
Stimulant: nutrient malabsorption, gastric irritation, elyte imbalance, discolored urine, rectal irritation
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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
Interactions
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Oral antibiotics decrease effect of lactulose Stimulants: decrease absorption antibiotics,
digoxin, tetracycline, oral anticoagulants
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Objective 15: identify features of an ideal laxative and cathartic◦ What do you think makes an ideal laxative?
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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
Obj 18- describe nursing interv associated with admin of laxatives.
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Objective 19: identify causes of diarrhea◦ What things, conditions can cause diarrhea?
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Objective 20: describe the uses of antidiarrheal agents
Objective 21: identify the antidiarrheal agents
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Antidiarrheal drugs: local or systemic action◦ Local: adsorb water to cause a formed stool◦ Systemic: act on autonomic nervous system to
decrease peristalsis
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Groups based on mechanism of action◦ Adsorbents◦ Antimotility◦ Bacterial replacement◦ Antisecretory◦ Enzymes
Antidiarrheals
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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
Mechanism of action
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Decrease: peristalsis, muscle tone Use with adsorbents, opiates Examples:
◦ Atropine◦ Hyoscyamine◦ Hyosine
Anticholenergics
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Decrease bowel motility Reduce pain Increased absorption of water & elytes
(absorption time)
Opiates
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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
Drug Effects
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Adsorbents: decrease digoxin, clindamycin, oral hypoglycemics. Methotrexate-toxicity
Anticholinergics: decreased effect with antacids. Increased anticholinergic effect with tricyclic antidepressants, MAOIs, amantadine & antihistamines
Interactions
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Opiates: additive CNS depression-alcohol, narcotics, sedative-hypnotics, antipsychotics, skeletal muscle relaxants
Pepto + oral anticoagulants
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Objective 22: describe the nursing implications associated with antidiarrheal agents
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Assess for cause of diarrhea◦ Medications◦ Infections◦ Diet◦ Lactulose intolerance◦ Emotional stress◦ Hyperthyroidism◦ Inflammation of gut◦ Surgical bypass of gut
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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
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◦ Dopamine antagonists◦ Serotonin antagonists◦ Anticholinergics ◦ Corticosteroids ◦ Benzodiazepines◦ Cannaboinoids
Objective 24: identify antiemetic drugs and their classification
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Objective 25: identify the mechanism of action, indications for use and desired effects of antiemetic drugs
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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
Dopamine antagonists
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◦ Phenothiazines mostly used ◦ Reglan popular
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chemotherapy, radiation, post op Block serotonin receptors in the CTZ and GI
tract Drugs include
◦ Dolasetron (Anzemet); granisetron (Kytril) and ondansetron (Zofran) prototype
Serotonin Antagonists:
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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
Anticholinergics:
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◦ Sometimes see Decadron◦ Don’t know its action
Corticosteroids
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◦ Active ingredient THC from marijuana ◦ Inhibit various pathways to the CTZ◦ Drugs include: dronabenol (Marinol) Do cause mind altering effects Can be abused
Cannaboinoids
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various activities such as sedation, depression of vomiting center, can cause amnesia◦ Examples: diazepam, lorazepam and midazolam
Benzodiazepines:
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New for chemo clients◦ Neurokinin receptor antagonist
Aprepitant (Emend)
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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 26: explain the use of emetics
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◦ What assessments would you make?
◦ What interventions would you initiate?
Objective 27: Describe the nursing process related to the administration of emetics/antiemetics
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