NR 565 FINAL EXAM WEEK 7 & 8 EXAM STUDY GUIDE LATEST UPDATED VERSION 2024, Exams of Nursing

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UPDATED VERSION 2024

NR 565 Exam Final Study Guide

➢ Antacids: weak bases that react with hydrochloric acid to form salt & water.

o Used in the treatment of Hyperacidity, GERD, PUD, hyperphosphatemia, and calcium deficiency

o Contain combinations of

▪ metallic cation (aluminum, calcium, magnesium, and sodium) ▪ and basic anion (hydroxide, bicarbonate, carbonate, citrate, and trisilicate) ➢ Pharmacodynamics, Pharmacokinetics, Pharmacotherapeutics

o Neutralize Gastric Acidity (causes ^pH of the stomach and duodenal bulb)

o Inhibit proteolytic activity of pepsin

o Increase lower esophageal sphincter tone

o Acid-neutralizing capacity ANC varies between products expressed in mEqs

o If ingested in a fasting state, antacids reduce acidity for approximately 20 to 40 minutes

o If taken 1 hr after a meal, acidity is reduced for 2 to 3 hrs

o A second dose taken after a meal maintains reduced acidity for more than 4 hrs after the meal

o The action of antacids occurs locally in the GI tract with minimal absorption, minimal metabolism

o ALL antacids are contraindicated in the presence of severe abdominal pain of unknown cause, especially if

accompanied by fever -HIGH SODIUM content: pts w/ HTN, CHF, marked renal failure, or on low-sodium diets need to use low sodium preparation -Concurrent administration with enteric-coated drugs, destroys the coating= alters absorption, ^ the risk for adverse effects -Administrations should be separated by at least 2 hours to decrease drug/drug interactions

1. Calcium based antacids : TUMS, Caltrate, Calcarb
   • Prescribed to treat calcium deficient states, i.e. chronic renal failure, post-menopause, and osteoporosis
   • Used to bind phosphates in CRF
   • Require Vitamin D for absorption from the GI tract
   • Excreted mainly in feces, 20% in urine
   • ADR: Contraindicated in the presence of hypercalcemia and renal calculi
   • Can cause constipation- increase bulk, fluids and mobility, stool softener
   • Administered 30min- 1hr on empty stomach or 3hr after meals
   • Should not be administered with food containing large amounts of oxalic acid (spinach, rhubarb), or phytic acid (bran, cereals), they decrease the absorption of calcium
   • Taking w/ foods containing phosphorus (milk, dairy) can lead to milk-alkali syndrome (N/V, confusion, headache).
   • Taking with acidic fruit juice improve absorption 2. Aluminum based: AlternaGEL, Amphojel, Mylanta
   • Inhibit smooth muscle contraction and slow gastric emptying
   • Used to bind phosphates in CRF Aluminum is not easily removed by dialysis b/c it is bound to albumin & transferrin = do not cross dialysis membrane

• Not absorbable with routine use
• Aluminum concentrated in the CNS
• Bind with phosphate and excreted in feces
• Prolonged use in patients with renal failure may result in dialysis osteomalacia o Aluminum deposits in bone and osteomalacia occurs
• Elevated aluminum tissue levels contribute to the development of dialysis encephalopathy

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• Used to treat

hyperphosphatemia in pts w/ renal failure & phosphate renal stone prevention

• Can cause constipation- increase bulk, fluids and mobility, stool softener

3. Magnesium based: Milk of mag, Maalox, Mylanta

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The malfunctioning kidney cannot excrete magnesium= hypermagnesemia

• Can be used to treat magnesium deficiencies from malnutrition, alcoholism, or mag-depleting drugs
• Contraindicated in patients with renal failure & used with caution in pts with renal insufficiency
• Not absorbable with routine use
• Excreted in the urine
• Contraindicated in patients with renal failure, use with caution for patients with any degree of renal insufficiency o Malfunctioning kidney is unable to excrete magnesium and hypermagnesemia may result
• Can cause diarrhea- increase fiber intake (Alkalosis may occur in renal impairment)

Clinical Use and Dosing

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➢ Rational drug selection

o ANC, sodium content, and cost

o Combination products with aluminum hydroxide and magnesium hydroxide have the highest ANC (use is

moderate to severe disease ➢ Monitoring

o Serum phosphate, potassium, and calcium during chronic use

o These drugs may cause increased serum calcium and decreased serum phosphate

o Chronic magnesium hydroxide use may cause elevated Mg levels in patients with renal failure or the elderly

with decreased renal function ➢ Patient education

o Take as prescribed, especially related to mealtimes

o Take 1-3 hrs after meals and at bedtime

o Chewable tablets chew thoroughly and drink half a glass of water

o Shake suspensions before administration

o Many drug interactions, separate doses by 2 hours apart

o Calcium based antacids should not be administer with food containing large amounts of oxalic acid (spinach,

rhubarb) or phytic acid (brans, cereals) decrease absorption

o Avoid taking with food containing phosphorus (milk, dairy products) can cause milk-alkali syndrome (NV,

confusion, HA)

o Consult provider: before taking antacids for more than 2 weeks if a problem recurs, if relief is not obtained,

or if symptoms of GI bleeding (black, tarry stools, coffee ground emesis

o Aluminum and calcium antacids may cause constipation: increase bulk, increase fluid intake, and more

mobility, stool softened

o Magnesium antacids may cause diarrhea, increase fiber

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o Avoid smoking, avoid flat lying body position while sleeping, foods that irritate the gastric mucosa (spicy

foods), or stimulate acid production (alcohol) and foods that decrease lower esophageal sphincter tone (caffeine, chocolate, fatty foods)

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➢ Antidiarrheals:

• Diarrhea that lasts for less than 2 weeks is considered acute; if it lasts more than 2 weeks, it is considered chronic.
• Pharmacodynamics, Pharmacokinetics
• Three main classes absorbent preparations (kaolin and pectin (Kapectolin) and bismuth subsalicylate (Pepto- Bismol, Kaopectate Liquid), opiates (diphenoxylate with atropine (Lomotil), diphenoxin with atropine (Motofen), and loperamide (Imodium)) and anticholinergics (IBD)
• Contraindications: Drugs that decrease gastric motility or delay intestinal transit time have induced toxic megacolon, especially in those with inflammatory bowel disease
• All antidiarrheals (except Crofelemer) require cautious use in older adults and when there is r/f impaction
• Older adults are especially sensitive to diphenoxylate or difenoxin r/t atropine and anticholinergic properties
• Not recommended for children under 12, none of the antidiarrheals are safe for children under 2 years old
• Antidiarrheals are contraindicated in the Tx of diarrhea in most children
• Standard of care: oral rehydration therapy
• ADRS Rebound constipation is the main adverse effect - Kaolin-pectin (kapectolin): Acute diarrhea
• Kaolin is a clay-like powder that attracts and holds onto bacteria
• Pectin thickens the stool by absorbing moisture
• Used to treat simple diarrhea
• Act locally in the bowel, not systemically absorbed
• Pregnancy Category B - Bismuth subsalicylate (Pepto bismol): Acute diarrhea, travelers’ diarrhea ▪ Antisecretory and antimicrobial effects ▪ Also used as part of a multidrug regimen for H. pylori ▪ Undergoes chemical dissociation in GI, salicylate moiety is absorbed ▪ Salicylate is metabolized in the liver and more than 90% is excreted in urine ▪ Contraindicated in children or teenagers during or after recovery from chickenpox or flu-like illness ▪ Contraindicated for patients with ASA hypersensitivity ▪ For bismuth subsalicylate, additional reactions that all patients should be warned about are gray/black stools and black tongue, the results of the bismuth. Patients should be told to expect this reaction and that it does not indicate GI bleeding. ▪ Bismuth subsalicylate may potentiate the risk for toxicity if taken w/ aspirin ▪ R/f hypoglycemia in large doses with insulin or oral hypoglycemics

-Crofelemer (fulyzaq): Symptomatic relief of noninfectious diarrhea in adult pts w/ HIV/AIDS on antiretroviral therapy ▪ Botanical blocking chloride secretion from the epithelial cells in the intestinal lumen, decreasing water loss and normalizing the flow of chloride and water in the intestinal tract ▪ Minimal absorption after PO administration ▪ Metabolism and excretion are not known ▪ In clinical trials more likely to have URI, bronchitis, and cough than placebo group ▪ Adverse GI effects flatulence, increased bilirubin, and nausea -diphenoxylate w/atropine (Lomotil): Acute diarrhea ▪ Constipating meperidine congener, lacks analgesic activity ▪ At high doses can produce euphoria and physical dependence

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▪ Anticholinergics are useful only with inflammatory bowel disease ▪ Well absorbed from GI tract

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▪ The atropine crosses the BBB (produces mild to moderate anticholinergic effects) ▪ Rapidly and extensively metabolized to diphenoxylic acid (it’s metabolite) ▪ Excreted in urine and feces ▪ The atropine component of diphenoxylate and difenoxin contraindicates their use in narrow-angle glaucoma and requires cautious use in prostatic hyperplasia. ▪ Children, especially those with Down syndrome have increased sensitivity to atropine ▪ Use with extreme caution in children, not recommended for use in children younger than 12 y/o ▪ Do not use with E. Coli, Salmonella, Shigella, or in pseudomembranous colitis ▪ ADRs: r/t atropine: anticholinergic effects (dry mouth, flushing, tachycardia, urinary retention) o Crosses BBB=dizziness, drowsiness, sedation, HA, euphoria, or depression ▪ Additive or potentiating CNS effects with other CNS depressants and additive anticholinergic effects with other drugs that share these effects -Difenoxin w/atropine (Motofen): Acute diarrhea9***** ▪ Anticholinergics are useful only with inflammatory bowel disease ▪ Rapidly metabolized to an inactive hydroxylated metabolite ▪ Excreted mainly as conjugates in urine and feces ▪ The atropine component of diphenoxylate and difenoxin contraindicates their use in narrow-angle glaucoma and requires cautious use in prostatic hyperplasia. ▪ Children, especially those with Down syndrome have increased sensitivity to atropine ▪ Use with extreme caution in children, not recommended for use in children younger than 12 y/o ▪ Do not use with E. Coli, Salmonella, Shigella, or in pseudomembranous colitis ▪ ADRs: r/t atropine: anticholinergic effects (dry mouth, flushing, tachycardia, urinary retention) o Crosses BBB=dizziness, drowsiness, sedation, HA, euphoria, or depression ▪ Additive or potentiating CNS effects with other CNS depressants and additive anticholinergic effects with other drugs that share these effects

- Loperamide (Imodium): Acute diarrhea, travelers’ diarrhea, chronic diarrhea associated w/inflammatory bowel disease - Binds to opiate receptors of the intestinal wall, slows gastric motility - Reduces fecal volume, increases viscosity and bulk, diminishes loss of fluid and electrolytes - Does not cross BBB, limited CNS ADRs - Partially metabolized by the liver and undergoes enterohepatic recirculation to be completely metabolized - Eliminated in feces - ADRs: r/t atropine: anticholinergic effects (dry mouth, flushing, tachycardia, urinary retention) o To a lesser degree than diphenoxylate and difenoxin o Dizziness and drowsiness (less CNS effects than difenoxin or diphenoxylate - Additive or potentiating CNS effects with other CNS depressants and additive anticholinergic effects with other drugs that share these effects

Pharmacotherapeutics

• Precaution and contraindications
• Drugs that reduce intestinal motility or delay intestinal transit time may cause toxic megacolon, especially in IBD
• Diphenoxylate with atropine difenoxin with atropine, and loperamide should be used cautiously in IBD o D/C if ABD distension occurs
• Use Diphenoxylate with atropine difenoxin with atropine, and loperamide use with caution in advanced hepatorenal disease and in all patients with abnormal LFTs (hepatic coma may occur)

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• Atropine: contraindicated in narrow-angle glaucoma and requires cautious use in prostatic hyperplasia
• Children (especially those with Downs syndrome) have increased sensitivity to atropine
• Clinical Use and Dosing

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Simple, Acute Diarrhea

• Absorbent preparations for adults: Kaolin-pectin or bismuth subsalicylate taken after each loose stool may be effective
• Majority of acute diarrhea are self-limiting, hydration important
• Maintain hydration o Commercial hydrating fluids (Pedialyte) or powdered salts o A pinch of table salt and a half-teaspoon of honey in 8 oz of fruit juice (older children and adults) o Non-diet colas without carbonations (older children and adults) o Alternate these solutions with 8 oz of water with one-quarter teaspoon baking soda to replenish electrolytes (NA, K, bicarbonate, and Cl)
• If the absorbents do not resolve the problem, diphenoxylate or difenoxin or loperamide may be added

Chronic Diarrhea Associated with IBD

• Steroids and sulfasalazine are needed
• Loperamide may be used as adjunct therapy o May significantly improve symptoms especially with added fiber and anticholinergics o If clinical improvement does not occur with doses of 16 mg/day for 10 days, symptoms are unlikely to be controlled by further use

Chronic Diarrhea Associated with Pancreatic Insufficiency

• Malabsorption r/t pancreatic insufficiency requires enzyme supplements, antidiarrheals not indicated

Chronic Infantile Diarrhea

• Bismuth subsalicylate: 2.5 mL every 4 hrs for children 2 to 24 months, 5 mL for 24-48 month children, and 10 mL for children 48 to 70 months

Diarrhea in HIV/AIDS Patients Taking Antiretroviral Drugs

• Crofelemer (Fulyzaq) symptomatic relief of noninfectious diarrhea in adults with HIV/AIDS on ARV therapy
• 125 mg tablet twice a day without regard for food Traveler’s Diarrhea
• Bismuth subsalicylate: two tablets or 2 Fl oz before each meal and at bedtime (QID) for up to 3 weeks
• Prevention and treatment
• High-risk areas: Central and South American, Africa, Middle East, Mexico, and Asia
• E. Coli is the most common causative agent followed by Campylobacter, Shigella, and Salmonella

Rational Drug Selection

• Indication: Acute diarrhea, any of the antidiarrheals are appropriate
• Subsalicylate and loperamide are the only drugs indicated for traveler’s diarrhea
• Loperamide is the only drug with an indication for IBD
• Generic and brand name formulations available

Monitoring: No specific monitoring

Patient Education

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• Take as directed, do not double doses, do not exceed max number of doses in 24 hrs
• Notify provider if diarrhea continues beyond 48 hrs or if ABD pain, fever, or distention occurs
• Use calibrated measuring devices for liquids, shake suspensions before measured

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• Drug interactions may occur, especially with diphenoxylate and loperamide
• Do not take any OTC antidiarrheal before contacting your provider if taking digoxin, cephalosporin antimicrobials, warfarin or heparin, or CNS depressants (including ETOH)
• R/f salicylate poisoning if taking ASA and bismuth subsalicylate
• R/f rebound constipation
• Stop drug when s/s of diarrhea are reduced
• Bismuth subsalicylate can turn the tongue and stools gray/black
• Drugs with atropine: dry mouth, flushing, tachycardia, and urinary retention
• Loperamide also exhibits these reactions but to a lesser degree, add fiber and use oral rehydrating solutions
• GHWT
• Bland food diet, remove milk, could it be lactose intolerance?

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➢ Cytoprotective Agents:

o Agents used to treat or prevent ulcer formation

o Two drugs sucralfate (Carafate) and misoprostol (Cytotec)

❖ Pt should report onset of black tarry stools or severe abdominal pain, which may indicate treatment

failure and GI bleeding Sucralfate (Carafate):

• Pharmacodynamics- Basic aluminum salt that binds to necrotic ulcer tissue where it acts as a barrier to acid, pepsin, and bile salts. o Action is largely topical, no acid-neutralizing activity, little is absorbed o May directly absorb bile salts and stimulate endogenous prostaglandin synthesis (formation of protective mucosa)
• Pharmacokinetics
• Minimal absorption, action is largely topical
• Essentially not absorbed, 90% excreted in feces
• Pharmacotherapeutics
• No specific precautions or contraindications
• Pregnancy Category B

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• Safety in children not established
• ADRs Minor and rare: constipation, dizziness, gastric discomfort
• Drug/Drug interactions : Decrease absorption of other drugs

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o Separate administration of interacting drugs by 2 hours, give other drug first

• Take on an empty stomach
• Causes constipation- increased fluids, dietary bulk, and exercise
• Do not use with digoxin or warfarin= decreases effectiveness
• Indication for active duodenal ulcer x8wks and maintenance after healing x2wks

Misoprostol (Cytotec):

• Pharmacodynamics: A methyl analogue of prostaglandin E
• Inhibits gastric secretion through inhibition of histamine-stimulated cyclic adenosis monophosphate (AMP) production
• Inhibits basal and nocturnal gastric acid secretion and acid secretion in response to stimuli o meals, histamine, and coffee by binding to prostaglandin E receptors, mucosal protective qualities.
• Mucosal protective qualities as well o Binds to prostaglandin E receptors which facilitate mucus and bicarbonate production
• Can be taken with food and still be effective
• Pharmacokinetics
• Rapidly and extensively absorbed after PO administration (distribution unknown)
• Rapidly converted into a free acid
• Does not affect CYP450 system
• Half-life is 20-40 mins however renal impairment doubles its half-life
• Metabolite excreted in urine
• Pharmacotherapeutics
• Use with caution with caution in renal impairment (no routine adjustments)
• Use with caution in the elderly r/t decreased renal function
• Pregnancy X: Can produce uterine contractions endangering pregnancy causing spontaneous abortion, premature birth, or birth defects. Women of childbearing age should have a negative pregnancy test before prescribed and start misoprostol on day 2 or 3 of menstrual period. If pregnancy is suspected, drug should be stopped immediately.
• ADRs GI or gynecological o Most common: diarrhea, ABD pain, nausea, and flatulence o Postmenopausal bleeding, spotting, cramps, hypermenorrhea, menstrual disorder, and dysmenorrhea
• Drug/Drug interactions: R/f increased diarrhea when given with magnesium based antacid
• Indicated for prophylaxis and treatment of duodenal ulcers associated with NSAID use

Clinical Use and Dosing

Prophylaxis and Treatment of Duodenal Ulcers Associated with NSAID Use

• NSAIDs inhibit prostaglandin synthesis and damage the mucosal lining of the stomach
• R/f ulcer formation
• Misoprostol is FDA approved for this use (prophylaxis or treatment)
• Dosage 200 mcg QID with food ACHS
• If unable to tolerate 100 mcg QID with food ACHS Treatment of Duodenal Ulcers from Other Causes
• Sucralfate used short term (up to 8 wks) for Tx of an active ulcer
• Dosage 1 gram QID on an empty stomach, 1 hr before meals, and HS
• Healing usually occurs in 2 weeks

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• Maintenance therapy after ulcer has healed is 1 g BID
• Off label use for treating gastric and esophageal ulcers-same dosing schedule
• May have some advantages over antacids and H2Ras in stress ulcer prophylaxis

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• Misoprostol: less effective for Tx of duodenal ulcers from other causes o Off-label: in doses >400mcg/day, Tx for duodenal ulcers not responsive to H2Ras

Rational Drug Selection

• Sucralfate: drug of choice for women of childbearing age
• Sucralfate preferred over misoprostol for treatment of active duodenal ulcers not caused by NSAIDs

Monitoring

• No specific monitoring parameters
• Negative pregnancy test for misoprostol

Patient Education

• Take exactly as prescribed
• Sucralfate on an empty stomach, Sucralfate is given for 4 to 8 weeks, increase fluid intake, dietary bulk, and exercise to reduce incidence of constipation
• Misoprostol with food, Misoprostol given for the duration of NSAID therapy, can cause diarrhea, if persists x1WK notify provider
• Continue therapy even if you feel better

➢ Antiemetics:

Drug classes with antiemetic properties: antihistamines, phenothiazines, sedative hypnotics, cannabinoids, 5-HT receptor antagonist, anticholinergics, and a substance P/neurokinin 1 receptor antagonist

Antihistamines: dimenhydrinate (Dramamine), diphenhydramine (Benadryl), hydroxyzine (Vistaril), meclizine (Antivert)

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• Pharmacodynamics: Antihistamines with significant antiemetic activity have strong anticholinergic effects as well as histamine 1 blocking effects
• MOA: Bind to central cholinergic receptors to produce antiemetic effects

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• especially with motion sickness due to the depression of conduction in the vestibulocerebellar pathway
• Pharmacokinetics: All the antiemetic drugs (except for TD scopolamine) are well absorbed after PO administration
• Pharmacotherapeutics: Cautious use in narrow-angle glaucoma, seizure disorders, pyloric obstruction, hyperthyroidism, CVD, and prostatic hypertrophy
• Contraindicated in severe liver disease r/t extensive liver metabolism
• Cautious use in the elderly, dose reductions may be needed
• Dimenhydrinate and diphenhydramine are Pregnancy Category B and safe for use in children
• Meclizine is pregnancy Category B (safety and efficacy in children less than 12 not established)
• Hydroxyzine Pregnancy Category C, has been used safely during labor (safety in children or lactation not established)

ADRs: Common adverse reactions : drowsiness, dry mouth, blurred vision & urinary retention

• Paradoxical excitation may occur in children
• Drug/Drug: additive CNS depression with other drugs that produce CNS depression and additive anticholinergic effects with other drugs that have anticholinergic effects or adverse reactions

Phenothiazines: prochlorperazine (Compazine), perphenazine, promethazine (Phenergan)

• Pharmacodynamics: block dopamine receptors in the chemoreceptor trigger zone (CTZ)
  • Also bind to and block cholinergic, alpha 1 adrenergic, and histamine 1 receptors
  • Use as antiemetics is limited due to sedating and EPM effects
• Pharmacotherapeutics: Produce extrapyramidal reaction Contraindicated in Parkinson’s Disease
  • Contraindicated in narrow-angle glaucoma, bone marrow depression, and sever CVD or hepatic disease
  • Cautious use in respiratory impairment cause by acute pulmonary infection or chronic respiratory disorders (asthma or emphysema)
  • May lead to the development of “silent pneumonia”
  • Suppress cough reflex, aspiration of vomitus is possible
  • Use with caution in those with r/f aspiration
  • Pregnancy Category C
  • Children of all ages are more prone to developing extrapyramidal reactions
  • Prochlorperazine: avoided in children younger than 5 r/t extrapyramidal reactions
  • R/f respiratory depression and sudden death in children 2 years of age or older
• Adverse reactions: drowsiness, (extrapyramidal reactions) dystonia, akathisia, tardive dyskinesia o Dry mouth, dry eyes, blurred vision, constipation, and urinary retention o ability to mask post-surgical and neurological conditions o potential for agranulocytosis and blood dyscrasias 4-10 weeks after initiation o can cause urine to turn pink to reddish brown (does not indicate hematuria)
• Promethazine Black Box Warning: Fatal respiratory depression in children younger than 2 years old
  • Drug/Drug: additive CNS depression with other drugs that produce CNS depression and additive anticholinergic effects with other drugs that have anticholinergic effects or adverse reactions
  • Additive hypotensive effects with antihypertensive agents or acute ingestion of ETOH
  • Concurrent administration of lithium increases r/f extrapyramidal reactions
  • May mask s/s of lithium toxicity
  • Antithyroid agents increase r/f agranulocytosis

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Cabbabinoid: dronabinol (Marinol)

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• Pharmacodynamics: Work in the CNS like cannabis to prevent NV associated w. chemotherapy & as an appetite stimulant, especially in HIV pts
• Pharmacotherapeutics: Use with caution in patient with Hx of seizure disorder r/t lowering of seizure threshold o Cardiac disorders : monitor for hypotension, possible hypertension, syncope, or tachycardia o High potential for abuse o Pregnancy Category C
• Adverse reactions: euphoria (should not drive), depression, dizziness, paranoid thoughts, somnolence, and abnormal thoughts o Cardiac effects include palpitations, tachycardia, and hypotension o Seizures and seizure-like activity o Drug/Drug interactions: Interacts with other CNS depressants, additive CNS depression with benzos, barbiturates, ETOH, opioids, antihistamines, muscle relaxants, and other CNS depressants

5-HT3 receptor agonists: palonosetron (Aloxi), dolasetron mesylate (Anzemet), granisetron (Kytril, Sancuso) and ondansetron (Zofran)

• Pharmacodynamics: Block serotonin both peripherally and on vagus nerve terminals & the chemoreceptor trigger zone (CTZ) to decrease emesis
• Pharmacotherapeutics: Potential to mask progressive ileus o Zofran contains aspartame, use with caution in phenylketonuria o Dolasetron, granisetron, and palonosetron are Pregnancy Category B
• Adverse reactions: constipation, headache, fatigue, dizziness, diarrhea. o Less common but concerning rare cases of tachycardia, bradycardia, hypotension, and QT prolongation

Anticholinergic: Scopolamine (Transderm Scop)

• Pharmacodynamics: Belladonna alkaloid anticholinergic acts as a competitive inhibitor of muscarinic in the parasympathetic nervous system o Blocks cholinergic transmission from the reticular center to the vomiting center in the brain o Anticholinergic effect: decreases secretion of saliva and decreases GI motility
• Pharmacotherapeutics: Contraindicated: pts w/ narrow angle glaucoma o Caution: pts with open-angle glaucoma or gastrointestinal or bladder neck obstruction o Use cautiously in the elderly due to CNS effects - Pregnancy Category C, no approved for use in children
• Adverse reactions: dry mouth, drowsiness, blurred vision, dilated pupils o Withdraw syndrome: dizziness, NV, HA
• Applied in the hairless area behind the ear 4 hours prior to needed effect and can be left in place up to 3 days. Wash hands after handling patch to avoid getting medication in the eyes (can cause blurry vision & pupil dilation)
• Decrease secretion of saliva and decrease gastric motility

NKI receptor antagonist: Aprepitant (Emend)

• Pharmacodynamics: crosses the blood brain barrier and occupies the NK1 receptors to prevent n/v in pts receiving chemotherapy
• Pharmacotherapeutics: Contraindicated in patients who are hypersensitive to any component of the product
  • Inhibits CYP3A4=increase serum concentrations of other drugs that are metabolized by CYP3A4
  • Pregnancy Category C and not approved for use in children ▪ Adverse reactions: fatigue, dizziness, hiccups, possible elevated ALT/AST, BUN

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• Drug/drug interactions: Inducer of CYP3A4 and can increase plasma concentrations of drugs metabolized via CYP3A4 system o Including: hormonal contraceptives and some chemotherapy agents

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• Concurrent use of Aprepitant and pimozide, terfenadine, astemizole, or cisapride is contraindicated due to potentially life-threatening reactions

Misc.: trimethobenzamide (Tigan)

• Pharmacodynamics: Inhibits emetic stimulation of the CTZ

Rational Drug Selection:

Treatment of Nausea and Vomiting Due to Drugs or Gastroenteritis

• Often improves with Tx using an antiemetic
• 5-HT3 receptor antagonists: low side-effect profile and tolerance
• Phenothiazines: also, a good initial and short-term treatment choice, not for children
• Trimethobenzamide: also, effective
• Antihistamines: can be used, less serious ADRs, better for longer term applications
• Dronabinol: only approved for use in chemotherapy associated NV and appetite stimulation
• Aprepitant: Approved for post-operative NV and in conjunction with other antiemetic agents for prevention of acute and delayed NV associated with initial and repeated doses of emetogenic CA chemo

Motion sickness:

• Antihistamines are useful r/t action on vestibular system and CTZ, rapid onset of action and prolonged effect
• Dimenhydrinate and meclizine: the most used
• Meclizine is also used to treat vertigo
• TD scopolamine: indicated for prevention of NV associated with motion sickness in adults and is commonly used in patients on ships

Monitoring:

• When used as a single dose or very short-term, no specific monitoring required
• If Tx for longer than a few days: following monitoring parameters are suggested
• Promethazine has been associated with bone marrow depression (CBC prior to initiating therapy)
• Phenothiazines associated with blood dyscrasias that occur between week 4-10 of therapy o CBC prior to initiating therapy and after 4 weeks

Patient Education

• Motion sickness: take 1 to 2 hrs prior to departure (except for ER-12 hrs prior)
• ADRs: drowsiness, dry mouth, dry eyes, constipation, and urinary retention
• Phenothiazines: turns urine pink to reddish brown: this is not hematuria

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