pharm - GI drugs Flashcards by nancy Gillcrist

what stimulates chief cells ? result?

ACh, CCK, gastrin –> release of pepsinogen

How well did you know this?

Not at all

Perfectly

prostaglandins in the stomach

are protective! stimulate mucous cell secretion (reduce inflammation)

vs rest of body where they cause inflammation

How well did you know this?

Not at all

Perfectly

ECL cell secrete

histamine

How well did you know this?

Not at all

Perfectly

major stimulatory mechanism for HCl secretion from parietal cells?

paracrine - histamine from ECL cells –> H2 receptor

How well did you know this?

Not at all

Perfectly

imbalance between aggressive and defensive stomach mechanisms

peptic ulcer disease

How well did you know this?

Not at all

Perfectly

antacids

neutralization of the HCl

4 –> aluminum hydroxide, magnesium hydroxide, calcium carbonate, and sodium bicarbonate

How well did you know this?

Not at all

Perfectly

tums

sodium bicarbonate/ca carbonate

may increase gassiness and bloating due to CO2 product

How well did you know this?

Not at all

Perfectly

antacids w effects on gastric motility

aluminum hydroxide –> DECREASE motility
magnesium hydroxide –> INCREASE motility
tums –> no effect

How well did you know this?

Not at all

Perfectly

which antacid INCREASES gastric motility?

mg hydroxide

How well did you know this?

Not at all

Perfectly

mucosal protective drugs

sucralfate (aluminum sucrose sulfate)
and
bismuth-subsalicylate

How well did you know this?

Not at all

Perfectly

sucralfate

aluminum sucrose sulfate
forms a water insoluble viscous layer over ulcer tissue - maintenance therapy
**give on empty stomach!
-few side effects (constipation/dry mouth)

How well did you know this?

Not at all

Perfectly

bismuth-subsalicylate

(pepto) does NOT neutralize acid –> binds to ulcer and
1) absorbs bile acids
2) stimulates mucous secretion
3) antibacterial effect on H pylori
* *aspirin sensitive people might be sensitive
* *turns stool black

How well did you know this?

Not at all

Perfectly

what drug forms a viscous water insoluble layer over ulcer; non curative just maintenance

sucralfate

How well did you know this?

Not at all

Perfectly

antimuscarinic agents?

dicyclomine and hycosamine

How well did you know this?

Not at all

Perfectly

dicyclomine and hycosamine use?

antimuscarinic agents —-UNPLEASANT, bad side effects, rarely used to treat PUD

How well did you know this?

Not at all

Perfectly

H2 receptor antagonists

and mechanism?

cimetidine, ranitidine

used to treat ulcers
mech: structural analogs to histamine –> competitively inhibit histamine binding to H2 receptors
—REDUCE ACID SECRETION

How well did you know this?

Not at all

Perfectly

Do H2 receptor antagonists have CNS side effects?

**they are hydrophilic so NO CNS side effects

How well did you know this?

Not at all

Perfectly

H2 receptor antagonists have a ____ half life.

why is this not an issue?

short (2-3 hrs)

lack of significant side effects allow high/multiple dosages

How well did you know this?

Not at all

Perfectly

which H2 receptor antagonist is the least ideal (most side effects)?
what are its negative effects?

cimetidine

enhances prolactin and binds androgen receptos leading to gynecomastia, impotence and lactation issues
inhbits cyt P450s –> prolongs half life of other drugs

How well did you know this?

Not at all

Perfectly

PPIs

proton pump inhibitors - used to treat ulcers
omeprazole, esomeprazole, lansoprezole, pantoprazole
mech: inhibit the H K ATPase of gastric parietal cells with an irreversible covalent bond(kills the pump)

How well did you know this?

Not at all

Perfectly

how PPIs get to the ATPase

prodrug as delayed release/enteric coated capsules–> absorbed as prodrug in duodenum –> circulation –> reaches parietal cell and is pumped into the acidic caniculi –> protonated by low pH –> active drug –> inactivates that same atpase

How well did you know this?

Not at all

Perfectly

PPIs are most effective when…

how long is the effect?

–>taken 30-60 minbefore eating
when you are hungry the pumps begin pumping
they have half life of 1 hr, but since the ATPases are irreversibly inhibited, effect lasts days until new ones can be made

treatment of choice for zollinger ellison syndrome?

PPI

omeprazole

what is more effective for GERD: PPI or H2 antagonists?

PPI

do PPIs have CNS effects?

yes

PPIs side effects

* CNS, nausea, diarrhea * prolonged suppression of acid secretion may increase c dificile colonization in stomach --> risk of pneumonia * risk of spinal/hip fracture * inhibits clopidrogel activation

Misoprostol

prostaglandin analog that inhibits gastric acid secretion and stimulates mucin secretion (protective just like PGE2)

why is misoprostol not used often?

1) PPIs are more effective and getting cheaper | 2) potential abortifacient --> doesnt allow/aborts pregnancies

antimicrobial therapy for peptic ulcers

many ulcers have H pylori infection Quadruple therapy - PPI + 2 antibiotics (tetracycline and metronidazole) + busmuth-subsalicylate Concomittant therapy - PPI + 3 antibiotics (clarithromycin, metronadizole/tinidazole, and amoxicillin)

concommittant antimicrobial therapy

PPI + 3 antibiotics | clarithromycin. amoxicillin, and metronidazole/tinidazole

quadruple antimicrobial therapy

PPI + bismuth-subsalicylate + 2 antibiotics (tetracycline and metronidazole)

metoclopramide

increases gastric motility D2 antagonist, 5HT3 antagonist, 5HT4 agonist *binding to 5HT4 increases motility in 3 ways = 1) increase LES pressure, 2) increases rate of gastric emptying, and 3) decreases small bowel transit time ----treats nausea associated with cancer treatment

why is metoclopramide not used alot?

central D2 side effects! hyperprolactinemia, galactorrhea, parkinsonism, tardive dyskinesia RISKY drug

cholinergic activity _____ motility | receptors?

increases D2 antagonists 5HT3 antagonists 5HT4 agonists

adrenergic activity ____ motility | receptors?

decreases opioid Mu receptor 5HT3 antagonists

emesis center

is the medulla - receives input from higher and lower areas and from area postrema (half in and half out of the BBB so good sensory) receptor trigger zone has 5HT3, D2, and M1 receptors

treatment choice for cytotoxic (chemotherapy) drug emesis/nausea

1) 5HT3 antagonists are best (ondansetron or palonosetron) 2) NK1 antagonist - aprepitant 3) metoclorpramide (D2/5HT3 antagonist) - last option due to bad side effects

aprepitant

nk1 antagonist | treats CINV from cytotoxic/chemo

ondansetron vs palonosetron

both are 5HT3 antagonists O - centrally acting - blocks peripheral and central emetic serotonin input P - better for CINV

treatment for severe IBD?

TNF inhibitors, monoclonal Ab (-mab) --> INFLIXIMAB or etanercept

treatment for mild/moderate IBD?

salazines they are converted to the active drug mesalamine (5-ASA) anti-inflammatory and aspirin analog (aspirin sensitive ppl watch out!)

what is used to treat gut after antibiotic treatments?

probiotics to repopulate gut

what drugs can cause increased h pylori populatiion?

PPIs

treatment options for diarrhea?

loperamide or alosetron

loperamide

an opioid mu agonist (doesnt penetrate CNS so low abuse potential) **DO NOT use with ulcerative colitis; can cause constipation and toxic megacolon

alosetron

5HT3 antagonist that blocks motility usually 5ht3 antagonists promote motility BUT this is an exception **ONLY use for diarrhea-predominant IBS

linaclotide

increases cGMP --> increased Cl/bicarb secretions in intestine treats constipation predominant IBS

lubiprostone

bicyclic FA that opens Cl channel | treats opioid induced constipation

naloxegol

opioid antagonist that doesnt enter CNS | treats opioid induced constipation

two drugs to treat opioid induced constipation

lubiprostone and naloxegol

bulk laxatives

mild and slow acting that add fiber and water to gut | bran, psyllium, and methylcellulose

osmotically active agents

promote water retention in distal ileum/colon sodium phosphate/bisphosphate (oral) polyethylene glycol

stimulant laxatives

promote accumulation of water and salts in the colonic lumen and stimulate motility --> POTENT AND QUICK (bisacodyl, senna)