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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