Gastrointestinal Drugs

Question 1

Antacids Mechanism of Action

Answer 1

Promotes gastric mucosal defense mechanism

Mucus Secretion: Protective barrier against HCl

Bicarb: Helps buffer acidic properties of HCl

Prostaglandins: Prevent activation of Proton Pump, leads to decrease HCl Production

NOTE: Antacids don’t prevent overproduction of Acid, but they do neutralize acid once it is in the stomach

Question 2

Antacid Drug Effects

Answer 2

Reduce pain associated with acid-related disorders

Question 3

Antacids: Aluminum Salts

Answer 3

Carbonate, Hydroxide

Constipating Effects, used with magnesium to fight constipating effects.

Examples: Basaljel (carb) , Alternagel (hydroxid) , Maalox, Mylanta (both combo)

Question 4

Antacids: Magnesium Salts

Answer 4

Carbonate, Hydroxide, oxide, trisilicate

Causes Diarrhea

Dangerous when used with Renal Failure

Example: Mag Hydroxide (MOM), Gaviscon, Combo: Maalox, Mylanta

Question 5

Antacids: Calcium Salt

Answer 5

Carbonate, but there are many forms

Can cause Constipation, and may result in kidney stones

Extra source of Calcium

Example: Tums

Question 6

Antacids: Sodium Bicarbonate

Answer 6

Very soluble

Buffers HCl

Quick onset, short duration

Causes metabolic alkalosis,** can cause problem inpatients with CHF, HTN, Renal insufficieny**

Question 7

Antacids/Antiflatulents

Answer 7

Antiflatulents: used to relieve painful symptoms associated with gas.

OTC Drugs: Activated charcoal and Simethicone

Question 8

Antacid Side Effects

Answer 8

Minimal

Aluminum/Calcium: Constipation

Magnesium: Diarrhea

Calcium Carbonate: Gas/belching

Question 9

H₂ Antagonists

Answer 9

Reduce acid secretion

Available OTC

Cimetidine/Tagamet

Famotidine/PEcid

Ranitidine/Zantac

Question 10

H₂ Antagonists: Mechanism of ACtion

Answer 10

Blocks Histamine (H₂) at receptors of parietal cells which results in decreased production of HCl

Question 11

H₂ Antagonist Side Effects

Answer 11

Cimetidine: Impotence/Gynecomastia

Headache, lethargy, confusion, diarrhea, urticaria, swearing, flushing

Question 12

H₂ Antagonist Drug Interactions of Cimetidine/Tagamet

Answer 12

BInds with P450 in liver, results in inhibitied oxidation of drugs and increased level of drugs

All H2 antagonists inhibit absorption of drugs that require acidic GI for absorption

Smoking decreases the effectiveness of H2 Blockers (increases gastric acid production)

Question 13

What is the action of the proton pump? Do H2 blockers and Antihistamines stop its action?

Answer 13

Parietal cells realese positive hydrogen during HCl production

They don’t stop the action.

Question 14

Proton Pump Inhibitors: Mechanism of Action

Answer 14

Irreversible bind to H+/K+ ATPase enzyme

Causes achlorhydria: blocking of gastric acid secretion

Question 15

PPI Drugs

Answer 15

“-prazole”

Prevacid, Prilosec, Nexium

Question 16

Indications for PPIs

Answer 16

Gerd Maintenance therapy

Treatment of H. Pylori ulcers

erosive esophagitis

Question 17

PPI Side Effects

Answer 17

Safe for short term

Protonix/Nexium parenteral administration

Can increase levels of diazepam/phenytoin, increased chance of bleeding with warfarin

Question 18

Sucralfate/Carafate

Answer 18

Cryoprotective

used for stress ulcers, erosions

Don’t give with other medications

Question 19

Misoprostol/Cytotec

Answer 19

Used for prevention of NSAID-Induced gastric Ulcers

Question 20

Antidiarrheals: Adsorbents MOA

Answer 20

Coat walls of GI, bind to toxin and eliminate through stool

Pepto-Bismol, Activated Charcoal, Kaopectate

Question 21

Antidiarrheals: Anticholinergics MOA

Answer 21

Decrease intestinal muscle tone and peristalsis

Donnatal/Atropine

Question 22

Antidiarrheals: Intestinal Flora MOA

Answer 22

Lactobacillus: supplies missing bacterie to GI, suppress diarrhea causing bacteria

Lactinex

Question 23

Antidiarrheals: Opiates MOA

Answer 23

Decrease bowel motility/relieve rectal spasms

Codeine, Lomotil, Imodium

Question 24

Antidiarrheals

Side effects of Adsorbents

Answer 24

Increased bleeding time, constipation, dark stools, tinnitus, hearing loss

Question 25

# Antidiarrheals Anticholinergics Side effects

Answer 25

urinary retention, impotense, headache, dizziness, confusion, dry skin, rash, blurred vision photophobia, Hypotension, hypertension, brady/tachycardia

Question 26

# Antidiarrheals Opiates Side Effects

Answer 26

Drowsiness, sedation, dizziness, lethargy, N/V, bradycardia, palpitations, Hypotension

Question 27

# Laxatives Bulk forming MOA and SE

Answer 27

High fiber, absorbs water, distends bowel Metamucil SE: Impaction/ fluid overload

Question 28

# Laxatives Emollient MOA and SE

Answer 28

Stool softener/lubricant more water/fat in stools Colace/Surfak Mineral oil SE: Skin Rash, decreased vitamin absorption

Question 29

# Laxatives Hyperosmotic MOA and SE

Answer 29

Increase fecal water content bowel distention, increased peristalsis GoLytely Sorbitol SE: Abdominal bloating, rectal irritation

Question 30

# Laxatives Saline MOA and SE

Answer 30

increase osmotic pressure within intestinal tract, causes more water to enter intestines Causes bowel distention, increased peristalsis, evacuation Examples: Epsom salts, magnesium hydroixide, fleet enema SE: magnesium toxicity, cramping, diarrhea, increased thirst

Question 31

# Laxatives Stimulant MOA and SE

Answer 31

Increase peristalsis via nerve stim. Castor oil, Senokot SE: nutrient malabsorption, skin rashes, gastric irritation, rectal irritation

Question 32

MOA of Antiemetic and Antinausea

Answer 32

Blocks vomiting pathway, blocks stimulus that induces vomiting

Question 33

# Antiemetics/antinausea Anticholinergic MOA/Indications

Answer 33

bind to ACh receptors in inner ear, blocks nauseating stimuli to CTZ Scopolamin, used for motion sickness

Question 34

# Antiemetics/antinausea Antihistamine agents H1 blockers

Answer 34

inhibit ACh by binding to H1 Prevents stim in vestibular/reticular area Benadryl, Phernergan also for cough, allergies, sedation

Question 35

# Antiemetics/antinausea Neuroleptics MOA

Answer 35

Block dopamine receptors on CTZ Thorazine, Compazine Also psychotic disorders, intractable hiccups

Question 36

# Antiemetics/antinausea Prokinetic agents

Answer 36

Block dopamine in CTZ stimulates peristalsis in GI Reglan

Question 37

# Antiemetics/antinausea Serotonin Blockers

Answer 37

Anzemet, Kytril, Zofran Used for N/V in patients getting chemo, also postop N/V

Question 38

# Antiemetics/antinausea THC MOA

Answer 38

Inhibits reticular formation, thalamus, cerebral cortex Marinol Used for N/V associated with chemo and anorexia with weight loss in AIDS patients

Question 39

Antiemetics/antinausea SE

Answer 39

Varies, due to nonseletive blocking Cause drowsiness Antiemetics + alcohol = CNS Depression