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RESP & GIT Pharmacology > GORD > Flashcards

Flashcards in GORD Deck (43):
1

Management of GORD

1. Reduce/suppress gastric acid secretion
2. Mucosal protection (barrier)
3. Neutralizing gastric acid
4. Eradicate H. Pylori

2

Proton pump inhibitors mechanism

-prazole’s

-irreversible inhibition of H+/K+ ATPase enzyme (proton pump)
-suppress H+ ions into lumen

Omeprazole: only one that has significant drug interactions (inhibits CYP450) - toxic side effects from other drugs

3

PPI side effects

-hypomagnesemia (in prolonged use
-risk of fractures and osteoporosis (incomplete absorption of calcium carbonate)
-clostridium difficile associated diarrhea NB
-prevent B12 absorbtion (acid required for absorbtion) -> anemia

4

H2 receptor antagonists

Reversibly binds H2 receptors in parietal cells of stomach

-gastric acid secretion response to other secretagogues also reduced
(Food, caffeine, Ach, gastrin)

-nocturnal acid hypersecretion: useful
-or in people allergic to PPI’s

5

H2 receptor antagonists SE

-not in pregnancy
-anti-androgenic effects

6

Cimetidine

H2RA
-inhibits CYP450 - more interactions

-also can be used to Rx molluscum contagiosum

7

Ranitidine

H2RA
-as effective as cimetidine, less SE and interactions
-little/no androgenic effects

8

Prostaglandins

Inhibit HCl secretion, wtimulates mucus and bicarbonate secretion and vasodilation of submucosa

-Misoprostol

-USE only in NSAID induced ulcers

9

Prostaglandin SE

-not in pregnancy (contraction of uterus)
-nausea & diarrhea

10

Sucralfate

Mucosal protective agent
-sucrose hydrogen sulphat-aluminum complex
-forms paste like gel when in contact with HCl - barrier

-Don’t use with any other med (at least 2h) - forms unabsorbable complex

11

Bismuth Subcitrate

High affinity for damaged tissue - coats

SE: blackening of tongue, stools
-renal faiure in prolonged Rx

12

Alginates

-used in pregnancy

13

Antacids

-doesn’t block acid production, but neutralizes

-aluminum hydroxide
-calcium carbonate
-magnesium
-sodium bicarbonate

14

H. Pylori eradication

Triple therapy
-7-14d regimen

1. PPI (for 1mo)
Any two of following:
-clarithromycin 500mg bd
-amoxicillin 1g bd
Metronidazole 400mg bd
Levofloxacin if resistant to clarithromycin

PPI CI - then use ranitidine + bismuth

15

Vomiting centre

5HT2 receptors
Achm receptors
H receptors

16

Stomach & intestines

Stretch receptors
Chemoreceptors
5HT3 receptors

-projections to chemoreceptor trigger zone and vomiting centre

17

Chemoreceptor trigger zone

D2 (central) receptors
5HT3 receptors
NK1 receptors (NB)

-projections to vomiting centre

18

Vestibular system

Achm
H1 receptors

-projections to chemoreceptor trigger zone and vestibular center

19

Antihistamines

-H1 blockers

20

Antihistamines SE

Anticholinergic SE

21

Promethazine

F

22

Cyclizine

F

23

Betahistine

D

24

Cinnarizine

F

25

Phenothiazines

Dopamine antagonists

-most common general purpose anti-emetic
-helpful in hiccups NBNB - numbs phrenic nerve which supplies diaphragm

-extra pyramidal SE

26

Benzamides

D

27

Butyrophenones

F

28

Domperidone

D

29

Haloperidol

D

30

Metoclopramide

Dopamine antagonist
-5HT4 stimulation (prokinetic)
-5HT3 antagonist at higher doses

-promotes gastric emptying

-all nausea except labyrinth disorders

-anti dopamine effects:
-extrapyramidal Sx

31

5HT3 receptor antagonists

-chemotherapy induced emesis

-SE: headache, QT interval prolonged (monitor in heart disease)

32

Ondansetron

F

33

Granisetron

Ss

34

Palonsetron

D

35

Dolasetron

D

36

Tropisetron

S

37

Benzodiazepine

D

38

Neurokinin Antagonists

Aprepitant

-neurokinin 1 receptor in brain - blocks substance P in CTZ and vomiting centre
-
-

39

Corticosteroids

Unknown mechanism of action

-used with cytotoxic drugs - large doses
-combo with NK1 Antagonists and 5HT3 antagonists

40

Cannabinoids

Dronabinol and Nabilone

-useful in cytotoxic therapy
-blocks descending pathways in cortical centres

41

Anti muscarinic agents

-decreased GI motlity and secretory activity
-muscarinic receptor blocking in vomiting centre and vestibular centre

-Don’t use in prostatic enlargement, or closed angle glaucoma, or intestinal obstruction

42

Hyoscine

Anti-muscarinic

-used in preventing motion sickness in short journeys
-not for long term use!

-can be used to relieve smooth muscle spasms (intestinal, biliary, or genitourinary)

43

Antimuscarinic SE

Think - fight or flight

-cardiac arrhytmias
-dry mouth
-constipation
-urinary retention
-respiratory collapse/apnoea