Sketchy Pharm: H2 Receptor Blockers, PPIs

Question 1

Which cells secrete gastric acid?

Answer 1

Parietal cells (Pour-It-All)

Question 2

What receptor/pump secretes protons?

Answer 2

The H+/K+ exchanger (powered by ATP)

Question 3

What kind of receptor is the H2 receptor?

Answer 3

Gs (think of the two S-shaped handles coming off the honey pot)

Question 4

The histamine that stimulates H2 receptors (on parietal cells) is released by __________________.

Answer 4

enterochromaffin-like cells (think of the guy leaf-blowing the beehive next to the Enter CarefuLly sign)

Question 5

What activates the enterochromaffin-like cells?

Answer 5

Gastrin from G cells in the antrum – which themselves are stimulated by peptides in the lumen of the antrum (think of the gas tank that is powering the leafblower)

Question 6

Gastrin binds to ___________ on the parietal cells.

Answer 6

CCKB

Question 7

True or false: the vagus nerve stimulates G cells to release gastrin using acetylcholine.

Answer 7

False. The vagus nerve uses gastrin-releasing peptide (GRP) to induce gastrin release from G cells.

Question 8

What two things stimulate gastrin release from the G cells?

Answer 8

• Vagus nerve stimulation by GRP

- Peptides in the lumen of the antrum

Question 9

List the H2 antagonists.

Answer 9

Famotidine
Ranitidine
Cimetidine
Nizatidine

(Think of the -tidine suffix and the boy wearing tie-dye.)

Question 10

True or false: H2 antagonists are great at treating meal-related GERD.

Answer 10

False. They are great at treating nocturnal GERD.

Question 11

Although PPIs are first-line, H2 antagonists have been shown to help treat ________________.

Answer 11

gastric and duodenal ulcers

Question 12

True or false: cimetidine is a CYP450 inhibitor.

Answer 12

True. (Think of the kid wearing tie-dye and jumping on the hood of the car.)

Question 13

Because of its antiandrogenic effects, cimetidine can cause ______________.

Answer 13

gynecomastia, prolactinemia, and impotence

Question 14

Galactorrhea is ___________________.

Answer 14

the inappropriate production of milk

Question 15

Why are PPIs more effective than H2 antagonists?

Answer 15

Because the K+/H+ exchanger is inhibited by PPIs, and that is the common end point for histamine-, gastrin-, and acetylcholine-mediated induction of acid secretion.

Question 16

Gastrinomas cause overactivation of which cell type?

Answer 16

ECL (this is Zollinger/Ellison syndrome)

Question 17

PPIs increase risk of what infections?

Answer 17

C. difficile (because the lack of acid promotes bacterial survival) and pneumonia

Question 18

Three things are less absorbed in those taking PPIs: _______________.

Answer 18

Fe, Mg, and Ca (leading to osteoporosis)

Question 19

Somatostatin inhibits _______________.

Answer 19

histamine release by ECL cells and gastrin release by G cells

Question 20

True or false: octreotide stimulates gastric acid secretion.

Answer 20

False. It is a long-acting analog of somatostatin that leads to the inhibition of histamine and gastrin release.