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Gastrointestinal > GI Pharmacology B&B > Flashcards

GI Pharmacology B&B Flashcards

1
Q

name 4 OTC antacids

A
  1. sodium bicarbonate (Alka Seltzer)
  2. calcium carbonate (Tums)
  3. aluminum hydroxide
  4. magnesium hydroxide
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2
Q

what are the potential side effects of sodium bicarbonate (Alka Seltzer), and why does this make sense? (3)

A
  1. bloating/belching - via CO2 production
  2. alkalosis - via bicarb (duh)
  3. fluid retention - via NaCl production

NaHCO3 + HCl <> NaCl - H2O + CO2

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3
Q

what are the potential side effects of calcium carbonate (Tums), and why does this make sense? (6)

A
  1. bloating/belching - via CO2 production
  2. alkalosis - via bicarb
  3. constipation - via Ca2+ (decreases GI motility)
  4. hypercalcemia - would really need to take a lot, but can be used for tx of hypocalcemia
  5. milk alkali syndrome (historic, if taken for ulcers): hypercalcemia + metabolic alkalosis + renal failure
  6. acid rebound - acid surge once antacid leaves stomach

CaCO3 + 2HCl <> CaCl2 + H2O + CO2

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4
Q

what are the potential side effects of aluminum hydroxide (antacid), and why does this make sense? (2)

A
  1. constipation - aluminum decreases GI motility.
  2. hypophosphatemia (would have to take a lot) - due to aluminum binding phosphate, which can be used in renal failure

Al(OH)3 + 3HCl <> AlCl3 + 3H2O

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5
Q

in which patients might you see aluminum toxicity, and why? how does it present? (3)

A

renal failure patients are sometimes given aluminum hydroxide (antacid) because aluminum binds phosphate - can be used to reduce hyperphosphatemia seen in renal failure

aluminum toxicity causes bone pain/muscle weakness/osteomalacia, dementia, ”iron resistant anemia” (microcytic anemia, does not improve with iron supplementation)

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6
Q

Pt w/ PMH of renal failure presents w/ fatigue and muscle weakness. PE is notable for pallor. Iron studies indicate a microcytic anemia. They are given iron supplements, but their condition does not improve. What is the cause of their “iron deficient” anemia?

A

aluminum toxicity: renal failure patients are sometimes given aluminum hydroxide (antacid) because aluminum binds phosphate - can be used to reduce hyperphosphatemia seen in renal failure

aluminum toxicity causes bone pain/muscle weakness/osteomalacia, dementia, ”iron resistant anemia” (microcytic anemia, does not improve with iron supplementation)

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7
Q

what are the potential side effects of magnesium hydroxide (antacid)? (2)

A
  1. osmotic diarrhea - poorly absorbed, sometimes used as osmotic laxative (“milk of magnesia”)
  2. hypermagnesemia (would need to take a lot) - hypotension, bradycardia

Mg(OH)2 + 2HCl <> MgCl2 + 2H2O

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8
Q

name 4 drugs that exhibit poor absorption in patients taking antacids

A
  1. tetracycline
  2. fluoroquinolones
  3. isoniazid
  4. iron supplements

this is because they bind the metals in antacids

[think of the metal ribbons in the Sketchy vids!]

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9
Q

name 4 histamine H2 receptor blockers

A
  1. famotidine
  2. ranitidine
  3. nizatidine
  4. cimetidine

[Famous Cinemas Ran Nicely]

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10
Q

what are the side effects of cimetidine that caused its disuse in the modern era? (4)

A

H2 blocker

  1. potent P450 inhibitor
  2. anti-androgen —> gynecomastia, impotence, prolactinemia
  3. cross BBB —> dizziness, confusion, headache
  4. reduces creatinine excretion
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11
Q

name 4 PPI

A
  1. omeprazole
  2. pantoprazole
  3. lansoprazole
  4. esomeprazole

[the OMElet in the PAN LANded SOMEwhere]

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12
Q

name 3 potential adverse effects of omeprazole, pantoprazole, lansoprazole, and esomeprazole

A
  1. Clostridium difficile infection - due to loss of H+ protection
  2. pneumonia - due to more pathogens in upper GI tract, due to loss of H+ protection
  3. malabsorption - Mg2+, Ca2+, B12, iron, vitamin C
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13
Q

what are the clinical uses of bismuth salicylate? (2)

A

aka Pepto-Bismol/ Kaopectate

  1. gastric ulcers/erosions - most effective in H. pylori ulcers (“quadruple therapy” instead of triple therapy)
  2. diarrhea - salicylate inhibits prostaglandins —> decreased mucus secretion into stool

note, bismuth reacts with hydrogen sulfide in the colon, forming black-colored stools (can look like GI bleeding)

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14
Q

what is the clinical use of sucralfate?

A

sucralfate = sulfated polysaccharide + aluminum hydroxide

negative charge binds to positively charged H+ in ulcers —> ulcer healing

side effects are rare because it is not absorbed

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15
Q

name 7 osmotic laxatives (there are others)

A
  1. magnesium hydroxide (milk of magnesia)
  2. magnesium citrate
  3. polyethylene glycol (Miralax)
  4. sodium polystyrene sulfonate (Kayexalate)
  5. sorbitol (sugar alcohol)
  6. sodium phosphate
  7. lactulose
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16
Q

what is the clinical use (2) of sodium polystyrene sulfonate (Kayexalate)?

A

“cation exchange resin” - binds potassium

can be used as osmotic laxative or to treat mild hyperkalemia

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17
Q

what is the special use of the osmotic laxative lactulose?

A

lactulose = synthetic disaccharide used as osmotic laxative but also to treat hyperammonemia

bacteria in colon break down lactulose into fatty acids —> lowers colonic pH, favors formation of NH4+ (not absorbable) over NH3

NH4+ is trapped in colon —> decreased plasma ammonia

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18
Q

what is the clinical use of bisacodyl (Dulcolax), senna (Senokot), and docusate?

A

bisacodyl (Dulcolax) and senna (Senokot) = “stimulant laxatives” (increase GI motility)

docusate = stool softener (also laxative)

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19
Q

MOA and clinical use of ondansetron

A

ondansetron = 5-HT3 receptor antagonist used as anti-emetic, esp. in chemo patients

5-HT3 R found in vomiting center in medulla and vagal/spinal nerves to GI tract

side effects = headache + contraption

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20
Q

MOA and clinical use (2) of metoclopramide

A

metoclopramide (Reglan) = D2 receptor antagonist

  1. in GI: block D2 = block ACh —> increased gastric motility, tx gastroparesis (esp. diabetics)
  2. in CNS: block D2 = block chemo trigger zone in area postrema (medulla) —> anti-emetic (esp. patients with migraines)

note, D2 blockade can also cause extrapyramidal symptoms (restless, akathisia, dystopia, tardive dyskinesia)

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21
Q

3 clinical scenarios in which metoclopramide is contraindicated

A

aka Reglan: D2 receptor antagonist, treats gastroparesis (diabetics) and anti-emetic (migraines)

contraindicated:
1. seizure disorder - lowers seizure threshold
2. Parkinson’s - bc of dopamine blockade
3. bowel obstruction - increased GI motility would make this worse

22
Q

When is the effect of H2 receptor antagonists most pronounced? (ex: famotidine, ranitidine, cimetidine, nizatidine)

A

effect is most pronounced on nocturnal acid secretion, which largely depends on histamine

23
Q

When should proton pump inhibitors be administered?
(ex: omeprazole, esomeprazole, lansoprazole, dexlansoprazole, pantoprazole, rabeprazole)

A

bioavailability is decreased half by food, so drugs should be administered on an empty stomach one hour before a meal

short half-life (0.5–2 hours), but acid inhibition lasts up to 24 hours due to irreversible in activation of H/K ATPase pump on gastric parietal cells

24
Q

MOA sucralfate

A

selectively binds and coats necrotic ulcer tissue – activation requires the acidic conditions in the gut (should not be taken together with H2 antagonist, PPIs, or antacids)

Acts as a barrier to acid, pepsin, bile, may also stimulate synthesis of prostaglandins (—> mucus, and bicarb secretion)

Effective in preventing and healing duodenal ulcers with minimal systemic affects due to lack of absorption

25
Q

MOA of bismuth subsalicylate / bismuth subcitrate?

A

bismuth: binds and coats necrotic ulcer tissue —> barrier to acid and pepsin and has direct anti-microbial activity against H pylori

salicylate: inhibits intestinal prostaglandin, and chloride secretion —> reduces stool frequency and liquidity

causes harmless blackening of the stool (can be confused for G.I. bleeding)

26
Q

which prostaglandin analog is approved for prevention of NSAID-induced ulcers?

A

misoprostol: PGE1 analog, stimulates mucus/HCO3 secretion

contraindicated in women with childbearing potential due to stimulate effect on the uterus

27
Q

MOA of psyllium, methylcellulose, and polycorbophil

A

bulk forming laxatives: indigestible colloids that absorb water, forming a bulky gel in the G.I. tract that distends colon and promotes peristalsis —> useful for management of intermittent constipation in patients not responding to high-fiber diet

bacterial digestion of plant fibers can lead to bloating and flatus

28
Q

MOA docusate, glycerin suppository, and mineral oil?

A

stool softeners: enhance penetration of water and lipids into the stool

Docusate used in hospitals to prevent constipation and minimize straining

Long-term use can impair absorption of fat soluble vitamins (DAKE)

29
Q

lavage solutions containing ______ are used for colonic cleansing prior to GI endoscopic procedures

A

polyethylene glycol: osmotic laxative

soluble but non-absorbable, alters osmolarity of fecal water in the colon

[bisacodyl (stimulant laxative) is also given in conjunction, orally or rectally]

30
Q

MOA of bisacodyl, aloe vera, senna, and cascara sagrada?

A

stimulant laxatives (cathartics) - stimulate enteric nervous system and secretion of colonic electrolytes and fluid

used for acute and chronic constipation, produce bowel movements within 6-12 hours when given orally or 0.5-2 hours when given rectally

31
Q

MOA lubiprostone

A

fatty acid derived from PGE1, activates type 2 chloride channels in GI epithelial cells —> prosecretory agent

treats constipation from chronic idiopathic constipation, IBS, opioid induced constipation

Like LUBE for the GI tract

32
Q

MOA linaclotide

A

peptide agonist of guanylate cyclase that activates CFTR chloride ion channels in GI epithelial cells —> treats constipation

treats chronic idiopathic constipation and IBS

lina[CL-]otide

33
Q

which of the following does NOT cross the BBB:
a. loperamide
b. diphenoxylate

A

both are mu-opioid agonists in enteric nervous system, increase colonic transit time - anti-diarrheal

loperamide does NOT cross BBB

at high doses, diphenoxylate can cross BBB and has potential for dependence

34
Q

which two mu opioid receptor agonists are appropriate for treatment of IBS with predominant diarrhea (IBS-D)?

A
  1. eluxadoline
  2. Loperamide

Agonist at mu opioid receptors - anti-diarrheal

antagonist at delta opioid receptors - analgesic properties to help with visceral pain

35
Q

MOA eluxadoline

A

Agonist at mu opioid receptors - anti-diarrheal

antagonist at delta opioid receptors - analgesic properties to help with visceral pain

treats IBS with predominant diarrhea (IBS-D)

36
Q

name three drug classes which are appropriate for treating IBS with predominant constipation (IBS-C) - indicate which is most effective

A
  1. Chloride ion channel activators – most effective (lubiprostone)
  2. Osmotic laxatives (polyethylene glycol)
  3. Bulk forming laxatives (psyllium)
37
Q

MOA of mesalamine, sulfasalazine, olsalazine, and balsalazide?

A

aminosalicylates: inhibit, inflammatory, mediators, derived from COX & LOX pathways

First line for mild to moderate ulcerative colitis and Crohn’s disease involving colon or distal ileum

Adverse effects include N/V, constipation, headache, myalgia, rash, altered liver enzymes

38
Q

MOA of infliximab, adalimumab, and certolizumab

A

mAb that bind both soluble and membrane-bound TNF —> suppressed TH1 immune response

approved for acute and chronic treatment of Crohn’s disease, infliximab approved for acute and chronic treatment of ulcerative colitis as well

39
Q

MOA of natalizumab and vedolizumab

A

natalizumab: mAb against alpha4 beta1 and alpha4 beta7 integrins

vedolizumab: mAb against alpha4 beta7 integrin

inhibited integrins = inhibited migrating lymphocytes

approved to treat Crohn’s disease and ulcerative colitis (in patients refractory to anti-TNF therapy)

rare risk of progressive multifocal leukoencephalopathy (PML) due to reactivation of latent HPV

40
Q

MOA aprepitant and netupitant?

A

neurokinin 1 (NK1) receptor antagonists: anti-emetic properties through central blockade in the area postrema

used in combination with 5-HT3 receptor antagonist and corticosteroids for prevention of acute and delayed chemotherapy induced nausea/vomiting (CINV)

note - inhibits the metabolism of drugs by CYP3A4

41
Q

at which receptors do dimenhydrinate, meclizine, and diphenhydramine act?

A

H1 antagonists - weakly antiemetic, useful for prevention/treatment of motion sickness

may cause sedation, dry mouth, urinary retention

42
Q

name a drug which treat Crohn’s disease by inhibiting the function of integrins on circulating inflammatory cells

A

natalizumab - mAb of alpha4 beta1/7

also vedolizumab

43
Q

Name a drug which is a first line agent for ulcerative colitis and Crohn’s disease by inhibiting inflammatory mediators derived from COX & LOX

A

mesalamine, sulfasalazine, olsalazine, balsalazide

44
Q

name a drug which treats constipation by activating type two chloride ion channels in G.I. epithelial cells

A

lubiprostone: fatty acid derived from PGE1

Produces a chloride rich fluid secretion that softens stool, increases motility, and promote spontaneous bowel movements

Treats chronic idiopathic constipation, IBS with predominant constipation (IBS-C), and opioid induced constipation

45
Q

name a D2 receptor antagonist that is both anti-emetic and prokinetic

A

metoclopramide - accelerates gastric emptying and also prevents vomiting

46
Q

which of the following is an osmotic laxative?
a. pysllium
b. docusate
c. polyethylene glycol
d. bisacodyl

A

c. polyethylene glycol

also Mg(OH)2 (milk of magnesium), sorbitol, lactulose

47
Q

which of the following is a bulk-forming laxative?
a. pysllium
b. docusate
c. polyethylene glycol
d. bisacodyl

A

a. pysllium

also methylcellulose, polycorbophil

48
Q

which of the following is a stool-softener?
a. pysllium
b. docusate
c. polyethylene glycol
d. bisacodyl

A

b. docusate

also glycerin suppository, mineral oil

49
Q

which of the following is a stimulant laxative?
a. pysllium
b. docusate
c. polyethylene glycol
d. bisacodyl

A

d. bisacodyl

also aloe vera, senna, cascara sagrada

50
Q

name a drug used to treat irritable bowel disease (IBD) that carries a rare but serious side effect of progressive multifocal leukoencephalopathy (PML)

A

natalizumab or vedolizumab

mAb to alpha4 integrins - prevent lymphocyte migration

may (rarely) cause PML due to HPV reactivation

Gastrointestinal (25 decks)

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