Antiacid Pharm/H. Pylori

Question 1

What are antacids?

Answer 1

Weak bases that work to neutralzie gastric acid most commonly for tx of heartburn (rapid onset, and short DOA)These wouldnt really be used for chronic things like GERD but more for the occasional heartburn

Question 2

What are the kinds of antacids?

Answer 2

Non-absorbables that work via Mg, Al, and Ca mostly andabsorbables that work via HCO3- (do not use longterm)

Question 3

Note that overloading on Na+ isnt going to be so good for the chronic renal failure pt.

Question 4

What is the role of H2-receptor binding?

Answer 4

promotion of gastric acid secretion by stomach parietal cells

Question 5

What are the H2-receptor antagonists?

Answer 5

-Cimetidine (Tagamet)Ranitidin (Zantac)Famotidine (Pepcid)Nizatidine

Question 6

How effective are H2 antagonists?

Answer 6

They are much more effective for tx of acid secretion overnight/in fasting states than compared to food-stimulated acid secretion. So these are best taken before bedtime and pts should not eat afterwardsTolerance will develop if used chronically

Question 7

The use of H2 receptor antagonists to treat peptic ulcers

Answer 7

Single nocturnal doses healed 80% of duodenal ulcers within 4 weeks and 80% of gastric ulcers within 8 weeks, with smokers doing worse and GERD pts. requiring more doses and they are unlikely to work in most pts (PPIs tend to work better for someone having heartburn very often like in GERD).NOTE: These are no longer indicated for tx. of peptic ulcers

Question 8

What is the most important factor in treating peptic ulcer disease?

Answer 8

determine the H. pylori status. If the pt. is +, tx the infection, and if they are negative, PPIs are superior to H2 blockers

Question 9

Cimetidine is a CYP inhibitor. What drugs increase in bioavailabilty when used concurrently with cimetidine?

Answer 9

-phenytoin-warfarin-theophylline-diazepam

Question 10

Erosive esophagitis pts. need a PPI

Question 11

You really want to try to get the pH up to around 4 to inhibit pepsin activity and H2 blockers dont go that high

Question 12

Describe the pharmacokinetics of PPIs?

Answer 12

They must be given as PO enteric-coated granules (in capsules or tablets) to prevent denaturation from gastric acid. As the gelatin capsule is broken down by the gastric acid in the stomach, the enteric-coated granules are dispersed and make it to the duodenum where the higher pH degrades the coating and the granules are absorbed. Once in the blood these granules act in the parietal cell H/K ATPase and then are metabolized by the liver (CYP2C19/3A4)

Question 13

What is the half-life of PPIs?

Answer 13

1-2 hrs. But they act longer than this

Question 14

T or F. PPIs block basal ANDfood-stimulated acid production

Answer 14

T. But they dont 100% suppress acid secretion (aka produce achlorhydria) due to H/KATPase constantly being re-synthesizedWhich expains their superiority in GERD over H2 blockers

Question 15

Do PPIs increase the risk of infection in the GI tract?

Answer 15

Yes, dose-dependent

Question 16

Does tolerance develop against PPIs?

Answer 16

No- they are not competitive inhibitors

Question 17

PPIs should be used in Erosive esophagitis! Much better than H2 blockers

Question 18

PO PPIs are indicated for minor ulcer bleeding if there isnt an identifable vessel at the base of the clot, and if there is– tx directly through the endoscope and keep the pt. on IV PPI for up to 72 hrs

Question 19

Other POTENTIAL AEs of chronic PPI use

Answer 19

-chronic kidney disease-dementia (OR: 1.33)-bone fractures-pneumoniathese are not set in stone

Question 20

What is sucralfate?

Answer 20

A macromolecule composed of sucros aluminum tat adheres to proteins in the GI tract and forms insoluble coagulum over ulcersThis works best at an acidic pH (so dont give with a PPI) and will also bind bile acids

Question 21

Main use now is biliary reflux

Question 22

causes cramps and diarrhea

Question 23

T or F. H. pylori ONLY lives on gastric mucosa

Answer 23

T. And that includes ectopic stomach tissue

Question 24

Causes about 60-70% of peptic ulcers and is the #1 cause of gastric cancer

Question 25

Note about clarithromycin tx of HP

Answer 25

If a pt. has taken clarithromycin for ANY reason in the past, DONT give to tx HP because it is probably resistant now (and probably metronidazole)BUT it hardly ever becomes resistant to amoxicillin or tetracycline