GI self study 1/30

Question 1

Dicyclomine (Bentyl)

Answer 1

anti-spasmotic by blocking muscarinic receptors on enteric plexus and smooth muscle

At high doses,has anticholinergic side effects like dry mouth,blurred vision

not frequently used

Question 2

sulfasalazine and its metabolite mesalamine

Answer 2

used to induce and maintain remission in IBD

active component is 5-aminosalicylic acid:may inhibit prostaglandin synthesis,block migration of neutrophils or act as a free radical scavenger

Question 3

AE of sulfasalazine

Answer 3

due to sulfapyridine component: nausea,GI upset,arthralgia,myalgia,bone marrow suppression,hypersensitivity reaction

AE worse in slow acetylators

supplement with folate

mesalamine can be given as rectal suppository

Question 4

immunosuppressive drugs for IBD

Answer 4

azathioprine and 6-mercaptopurine for moderate disease

they allow reduction in glucocorticoids

in more severe cases,cyclosporine can be used

Question 5

methotrexate

Answer 5

better for moderate Crohn than UC (unclear results)

Inhibits DHFR

Question 6

Anti-TNF (infliximab)

Answer 6

used for moderate to severe disease

Question 7

Metronidazole+tinidazole

Answer 7

members of nitroimidazole. Nitro group is reduced in anaerobic bacteria and sensitive protozoans–> reactive products are cidal against obligate anaerobes

against C-dfi, G lamblia, E histolytica also against bacteroides, fusobacterium and trichomonas. Moderately against H pylori

Question 8

AE of metronidazoles

Answer 8

n, headache,anorexia,metallic taste,disulfiram like reaction

inhibit warfarin metabolism

Question 9

TMP-SMX and fluoroquinolones

Answer 9

against salmonella,shigella,E coli and campylobacter

Question 10

Erythromycin

Answer 10

against severe cases of campylobacter

Question 11

Iodoquinol

Answer 11

used with metronidazole to treat amebic infxn.

most drug stays in lumen–> diarrhea and rash

Question 12

H2-R antagonists

(cimetidine,famotidine,ranitidine)

Answer 12

inhibit H2-R of parietal cells–> decrease in pepsin

only once or twice a day

Used for dyspepsia,GERD,PUD

AE=cimetidine has anti-androgenic–> gynecomastia and is also inhibitor of CYP450

Question 13

PPI

(lansoprazol,omeprazole,esomeprazole)

Answer 13

prodrugs administered as enteric coated tablets. when the uncharged form passes into acidic canaliculus–> converted to active sulfenamide form–> inhibit H/K ATPase

PPI suppress H secretion better and longer than H2-I

used for PPI,GERD,ZE

can also be given IV

Question 14

AE of PPI

Answer 14

poor absorption of Ca–> fractures

increase in C-dif and possible link with pneumonia

extensively metabolized by CYP450

omeprazole may inhibit metabolism of warfarin,diazepam,phenytoin,carbamazepine

Question 15

gastric antacids= AlOH3 and MgOH2, CACO3

Answer 15

neutralize acid

for acid indigestion, may be used for PUD but hard to dose properly, CaCO3 can be used as Ca supplement, Ca citrate is absorbed better in pts on PPI

Al alone–> constipation, Mg–> diarrhea

therefore they’re administered together (Maalox,Mylanta)

CaCO3 can lead to greater absorption of sodium bicarb

–> metabolic alkalosis and CO2 liberated can cause flatulence

Question 16

Sucralfate (mucosal protective)

Answer 16

sulfated polysaccharide–> adheres to ulcer craters and epithelial cells–> inhibit pepsin-catalyzed hydrolysis of mucosal proteins and stimulates PG synthesis–> healing of ulcer

Can inhibit absorption of digoxin

Question 17

Bismuth subsalicylates

Answer 17

anti-secretory, anti-inflammatory and anti-microbial effects

relieves n/v (Pepto-bismol)

dark stool and black staining of tongue caused by bismuth sulfide formed in a reaction between drug and bacterial sulfides in GI

contains salicylates–> watch for ASA allergy

Question 18

drug regimen for H pylori

Answer 18

1-5 days=PPI+amoxicillin

6-10 days=PPI+clarithromycin+metronidazole