Gastointestinal Pharmacology Flashcards Preview

Pharmacology Quiz 4 > Gastointestinal Pharmacology > Flashcards

Flashcards in Gastointestinal Pharmacology Deck (53)
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1
Q

What is the pathogenesis of gastroduodenal ulcers?

A

Excess gastric acid secretion, breakdown of mucosal cytoprotection, Helicobacter pylori infection

2
Q

What are the goals of ulcer treatment?

A

reduce ulcerogenic factors, enhance defensive factors, or eradicate any infectious causes

3
Q

What are pro-ulcerogenic factors?

A

Acids (HCl, VFA, bile acids), pepsin, infections

4
Q

What are antiulcerogenic factors?

A

mucosal cytoprotection, epithelial renewal, external protection

5
Q

How does one increase the gastric pH to greater than 4 to promote healing?

A

H2-Histamine receptor blockade, stimulation of gastric PGE receptors, gastric H+-K+-ATPase inhibition (proton pump inhibitors)

6
Q

Famotidine

A

H2-Histamine antagonist, decreases acid secretion which decreases pepsin. As treatment continues effectiveness decreases due to an increased secretion of gastrin. Low oral biovalibility and renal clearance

7
Q

What are examples of H2-histamine antagonists?

A

famotidine, ranitidine, cimetidine

8
Q

What are the side effects and indications of H2-histamine antagonist?

A

Renal disease patients need lower dose, treatment of ulcers due to gastritis, stress, NSAID terapies, gastrinomas

9
Q

Misoprostil

A

PGE analogue, po administration, needs frequent administration due to rapid hepatic metabolism. Decreases acid secretion stimulated by histamine or gastrin. Less effective than H2-HR antagonists or PPI, increases gastric cytoprotection

10
Q

How do PGE and PGI promote cytoprotection?

A

Mucus production (coats surface of the gastric mucosa), bicarb production (neutralizes HCl), intrinsic mucosal barrier (resist back-diffusion of acid), and gastric blood flow (flushes away acid, prevents buildup, maintains tissue pH in normal range)

11
Q

Indications/side effects/contraindications of misoprostil?

A

NSAIDs-induced ulcers, increased mast cell influx. Side effects include diarrhea due to prokinetic action. Contraindications include IBD, pregnancy

12
Q

What is an example of a proton pump inhibitor?

A

Omeprazole

13
Q

What is the action of proton pump inhibitors?

A

Irreversibly inactivate H+/K+ ATPase, so effects extend longer than the drug’s presence in the body. Reduce acid secretions

14
Q

Omeprazole

A

Proton pump inhibitor. Oral paste that is a weak base that decreases the release of HCl

15
Q

Sucralfate

A

Binds to ulcerated tissue to form a seal after oral administration, heals existing ulcers not prevent new ones. Short duration of action. Binds and inactivates bile acids, increases local prostanoid formation.

16
Q

Antacids

A

Either systemic or non-systemic, non-systemic only affects stomach. Maalox and Mylanta examples. Relieve clinical signs, no healing.

17
Q

Na or Ca carbonate antacids onset

A

rapid

18
Q

Mg salts (sulfate, hydroxide) onset

A

intermediate with laxative effect

19
Q

all hydroxide antacids onset

A

slow

20
Q

What is the best type of drug to use to treat an ulcer: PPIs, H2-histamine antagonists, or cytoprotectants?

A

PPIs

21
Q

What are examples of locally-acting emetic agents?

A

warm water, sodium chloride, 3% hydrogen peroxide, syrup of ipecac (emetine akaloid substance)

22
Q

Apomorphine

A

centrally acts on D2 dopamine receptors, produces vomiting in 2-10 minutes

23
Q

Xylazine

A

simulates alpha2-adrenergic receptors to produce emesis in cats

24
Q

Indications of anti-emetic drugs

A

motion sickness, uremia, liver disease, cancer chemo, parvo, trauma

25
Q

Famotidine

A

H2-histamine antagonist that lessens irritating effects of acid on the stomach

26
Q

muscarinic acetylcholine antagonist anti-emetic effects

A

decrease vagal afferent transmission to vomiting center to decrease vomiting

27
Q

kaolin-pectin and other coating agents anti-emetic efficacy

A

not very effective

28
Q

Metoclopramide

A

Simulate gastric motility, block CNS dopamine receptors and 5-HT3 receptors

29
Q

Action of diphenhydramine, meclizine

A

may reduce motion sickness by blocking histamine and muscarinic cholinergic receptors

30
Q

Ondanestron

A

blocks type three serotonin receptors on gastric vagal fibers and are effective at inhibiting emesis in dogs associated with chemo or parvo

31
Q

Maropitant

A

Blocks type 1 neurokinin (substance P) receptors present in vomiting center, broad spectrum anti-emetic

32
Q

What effect do mAChR antagonists have on the GI tract?

A

increased peristalsis

33
Q

What affect do opiods have on the GI tract?

A

increased segmentation

34
Q

What affect do opiod antagonists or mAChR antagonists have on the GI tract?

A

inhibit increased segmentation

35
Q

Bethanechol

A

mAChR agonist that is a cholinomimetric that increases GI motility

36
Q

Neostigmine

A

anticholinesterase drug that increases GI motility

37
Q

Ranitidine and Nizatidine

A

weak cholinesterase inhibitors that can increase upper GI motility

38
Q

Metoclopramide

A

Acts on upper GI tract to increase smooth muscle contractions, blocks D2 dopamine receptors and is an agonist at the 5-HT4 serotonin receptors

39
Q

Cisapride

A

Partial agonist at 5-HT4 receptors, increase acetylcholine release from enteric neurons to stimulate motility, indicated by chronic constipation, ileus in dogs

40
Q

Erythromycin

A

agonist at receptors in smooth muscle and gastroenteric nerves for motilin, stimulates motility of stomach and upper SI (not colon). Metabolized by CYP450 and eliminated in bile

41
Q

Lidocaine

A

Blocks voltage-gated Na+ channels in enteric nerves, stimulates intestinal motility although mechanism unclear

42
Q

What are contraindications of prokinetic drugs?

A

GI tract obstructions and post-surgical anastomoses

43
Q

What are the major types of laxatives and cathartics?

A

Osmotic, bulk, lubricants/surfactants, and irritants

44
Q

What are examples of osmotic laxatives?

A

Mannitol, sorbitol (draws water into intestinal tract)

45
Q

What is an example of a irritant laxative?

A

Bisacodyl- stimulates enteric sensory nerves to increase intestinal motility and decrease water absorption

46
Q

What is an example of a bulk laxative drug?

A

Canned pumpkin- increase mass of non-digestible matter

47
Q

What is an example of a lubricant/surfactant laxative drug?

A

Mineral oil, docusate sodium- coat fecal surface with hydrophobic film

48
Q

Bismuth subsalicylate

A

breaks down to salicylic acid (NSAID) and bismuth oxychloride (bacteriocide?), bismuth salts absorb enterotoxins

49
Q

Kaolin-Pectin

A

Aluminum silicate, changes fecal consistency (maybe??) but clinical efficacy questionable

50
Q

Propantheline, Isopropramide, N-butylscopolammonium bromine

A

Types of quarternary ammonium anticholinergic drugs (act through intestinal mAChR) that do not enter CNS and inhibit intestinal motility and secretion as antidiarrheal drugs

51
Q

Naloxone

A

antagonize opiod actions in GI tract (opiods inhibit GI propulsion)

52
Q

What are examples of opiate antidiarrheal drugs?

A

Loperamide (no abuse) and codine (acts at perif and CNS cites too)

53
Q

What are examples of opiod antagonists that are peripherally-specific?

A

Alvimopan and methynaltrexone