Chapter 6 GI agents - acid reducing agents and dysmotility agents

Question 1

amoxacillin
clarithromycin
metronidazole
tetracycline

Answer 1

H pylori ulcers

• effective therapy requires at least 2 AB and an antisecretory agent or bismuth

Question 2

cimetidine (tagamet)
ranitidine (zantac)
famotidine (pepcid)
nizatidine (Axid)

h2 histamine receptor antagonist

Answer 2

• decrease gastric acid secretion by reversibly binding to histamine H2 receptors located on gastric parietal cells, thereby inhibiting the binding and activity of the endogenous ligand histamine.

indication
* duodenal/gastric ulcer
* hypersecretion of acid
* GERD (stomach contents move up into the esophagus.)
* nizatidine —- benign gastric ulcers

effects
* diarrhea
* dizziness
* rash
* headache/confusion/somnolence
* decreased libido, impotence
* all drugs, compared to cimetidine, possibly less CNS and sex disturbance

cimetidine – caution with 50 y/o or older w/ kidney + liver failure

interaction
* mainly cimetidine — inc concentration of anticoagulant, theophlline, lidocaine, phenytoin, benzo’s, nifedipine, propranolol, others — ALTERS serum of many drugs

Question 3

Calcium carbonate

antacid

Answer 3

• decrease gastric acid secretion by reversibly binding to histamine H2 receptors located on gastric parietal cells, thereby inhibiting the binding and activity of the endogenous ligand histamine. (h2 histamine receptor antagonist)
• duodenal ulcers, benign gastric ulcers

effects
* constipation
* hypercalcemia
* metabolic alkalosis
* hemorrhoids + bleeding anal fissures
* milk-alkali syndrome — taken w/ milk or bicarbonate (rare)

contra
* older than 50 with kidney or hepatic failure

Increase gastric absorption of drugs normally absorbe in small intestine

Question 4

Magnesium salts

antacid

Answer 4

• decrease gastric acid secretion by reversibly binding to histamine H2 receptors located on gastric parietal cells, thereby inhibiting the binding and activity of the endogenous ligand histamine. (h2 histamine receptor antagonist)

indication
* duodenal ulcers, benign gastric uclers

effects
* diarrhea
* hypermagnesemia (n/v, hyporeflexia, decreased muscle tone)

contraindication
* diarrhea
* decraesd renal fx (l/t hypermagnesmia)
* malabsorption syndrome

quickly excreted by kidney

Used with aluminum or calcium antcaids to prevent constipation!

Question 5

Na+ citrate

antacid

Answer 5

• decrease gastric acid secretion by reversibly binding to histamine H2 receptors located on gastric parietal cells, thereby inhibiting the binding and activity of the endogenous ligand histamine. (h2 histamine receptor antagonist)
• preferred pre-op antacid

effects
* horrible taste
* better for sedated patients

contradincation
* CHF
* HTN

Question 6

sucralfate (carafate)

misc

Answer 6

• sucros and polyaluminum hydroxide polymerize at LOW PH to form protective coating

indication
* prophylaxis/tx of duodenal uclers

effect
* constipation

can interfere with absorption of other drugs, particularly fluoroquinoline antibiotics
* careful w/ dialysis pts d/t aluminum concentration increasing!

Question 7

metoclopramide (reglan)

msic

Answer 7

• inc rate of gastric emptying by unknown mech

indication
* reflux esophagitis (inflammation of the esophageal mucosa secondary to gastroesophageal reflux disease)
* pre-op gastric emptying

effects
* diarrhea
* constipation
* drowsiness + depression
* EPS d/t dopamine antagonism

contra
* elderly + children more susceptible to EPS

interactions
* sharply inc risk of HTN w/ MAOIs
* inc toxicity of antipsychotics
* reduce absorption of many drugs

Question 8

omeprazole (prilosec)
lansoprazole (prevacid)
dexlanoprazole (dexilant)
esomeprazole (nexium)
pantoprazole (protonix)
rabeprazole (aciphex)

misc

Answer 8

• inhibits H+/K+ ATPase (proton pump) of parietal cell
• RESULT – decreased acid secretion

indication
* reflux esophagitis
* duodenal ulcer
* hypersecretory states

effects
* constipation
* gastric carcinoid tumors in rats…!

Omeprazole interacts with warfarin, phenytoin, and diazepam

Question 9

misoprostol (cytotec)

misc

Answer 9

• increases HCO3 – bicarbonate and mucin release
• reduces acid secretion

effects
* abortion (uterine contraction){
* abdominal pain

contraindications
* pregnancy

THIS drug is a prostaglandin E analog