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62 Cards in this Set
- Front
- Back
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what are some therapies for PUD and hyper-acid secretion?
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H2 antag
M3 antag PPI somatostatin antag protectants tx H. pylori |
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what are the H2 antagonist?
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cimetadine
ranitidine nizatidine famotidine |
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what is the mech of H2 antagonists?
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H2 antag
selectively antagonist H2 receptor on PARIETAL CELLS - decreases intracellular cAMP - reduces intracellular Ca++ - reduced act of proton pump --> inhibit BOTH mean and basal acid secretion |
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are H2 antagonist effective for chronic oral admin?
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yes
bioavailability is drug-dependent (45% famotidine - 90% nizatidine) |
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how are H2 antag excreted? 1/2 life?
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unchanged in the kidney
1/2 life = 1.5-3 hrs |
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what is special about cimetadine??
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cimetadine is the ONLY H2 antag that will INHIBIT P450 enzymes
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why would you use an H2 antag?
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inhibit gastic acid secretion
-PUD (both duodenal & gastric) -dyspepsia -GERD -hyper-secretory (zollinger-ellison) also-- in combination w H1 antag for allergies |
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T/F
H2 antags work well in combination with both antacits & PPIs |
NOOOO!
H2 + antacids = little benefit H2 + PPI = H2 decreases PPI efficacy |
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T/F
H2 antags + antibiotic = effective in tx of H. pylori |
true
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T/F
H2 antags have increased efficacy in smokers & elderly |
false - REDUCED efficacy
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which H2 antag has the MOST side effects? and what are they?
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cimetidine
-inhibit P450 (2C9, 2D6, 3A4) -weakly anti-androgenic- antag for testosterone receptors in elderly men -impotence -lipophilic- CAN cross BBB (slurred speech, delirium, confusion) general: dizziness, constipation, diarrhea, HA |
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what receptor do muscarinic antagonist block? what does this cause?
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block M3
- decrease Ca++ --> decrease activitiy of proton pump - decreased GI propulsion - heart = increase HR - salivary = decrease salivation -eye = loss of accommodation not used clinically if responsive to other PUD-hypersection drugs (without antimuscarinic side effects) |
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what are the muscarinic antags?
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pirenzepine
propantheline dicyclomine trihexethyl glycopyrrolate |
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which drug works by M1 antagonism - blocking release of histamine from paracrine cells?
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pirenzepine
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what cells are M1 and M3 receptors located?
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M1 = ECL cell
M3 = parietal cell |
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what are the PPI drugs? are they prodrugs?
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omeprazole
lansoprazole rabeprazole yes, prodrugs converted to active form in acidic environment |
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what is the mech of action for PPIs
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inhibits H+/K+ ATPase in luminal membrance of PARIETAL cell
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what class of drugs are the MOST effective at decreaseing H+ secretion?
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PPIs
since ALL secretory agents will increase pump activits - histamine - gastrin - acetylcholine |
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PPIs:
oral absorbtion? 1/2 life? metab? |
oral 75-80% absorbed
1-1.5 hrs hepatic metabolism |
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T/F
PPIs are effective reversible inhibitors of most H+/K+ ATPases |
false
IRreversible inhibitors of ALL H+/K+ ATPases therefore LITTLE correlation btwn plasma 1/2 life and duration of action inhibit acid secretion 24-48 hours |
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what is the DOC for Zollinger-Ellison syndrome?
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PPIs
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tx H. pylori?
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ampicillin + PPI for 10-14 days
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what is the most efficacious drug class for txing GERD?
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PPI
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what are the side effects of PPI?
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minor
gastic mucosal hyperplasie - rare |
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what are the protectants?
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sucralfate
misoprostol bismuth-subsalicylate carbenoxolone |
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which protectant increases mucus secretion?
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misoprostol
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which protectant is a synthetic derivative of glycyrrhizic acid and N/A in USA?
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carbenoxolone
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what are the 5 mech involved with sucralfate?
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1. complexes w protein at ulcer to form protective layer
2. stimulats prostaglandin secretion 3. decreases back-diffusion of H+ 4. bind to and inactivate pepsin and bile salts 5. suppresses H pylori infection--> decreasing further acid secretion |
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T/F
protectants are well absorbed from the gut |
false
poorly absorbed orally. excreted in feces used for PUD NOT AS EFFECACIOUS as h2 or PPIs, tho |
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side effects of protectants?
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minimal- not much is actually absorbed (you want it to stay in the gut!)
caution in renal dysfxn-- aluminum may be absorbed |
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what drug is used in PUD by pts with chronic NSAID use for arthritis tx?
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misoprostol
inhibits activity of adenylate cyclase in PARIETAL cells --> reduces cAMP |
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side effects of misoprostol?
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diarrhea
uterine stimulation |
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tx of H. pylori?
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start = acid-reducing agent (H2 blocker or PPI)
then tx w/ 2 or more of the following: amoxicillin, bismuth, clarithromycin, metronidazole, tetracycline tx regimne = acid inhibitor for 6-8 wks & antimicrobial agent for 2 weeks success > 90% |
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antacids contain cations and neutralize secreted acid..
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contain Na/Ca/Mg/Al
form "soaps" excreted in feces neutralize acid-- does NOT stop / prevent additional secretion |
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what are the 2 desired effects of antacids?
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1. decrease total acid "load"
2. inhibit the activity of pepsin at pH of 5 |
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which antacid cation:
has rapid onset & short duration? |
Na & K
(pH 5-7) side effect: alkalosis |
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which antacid cation:
has rapid onset, but effect only lasts as long as it is present |
Ca
(pH 4-5) can increase the secretion of gastrin --> leads to acid rebound when Ca empties |
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which antacid cation:
rapid onset with pH 8-9 |
Mg
side effect: diarrhea |
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which antacid cation:
slower onset |
Aluminum
side effect: constipation |
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drugs used to treat IBD (UC and Crohn's)
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glucocorticoids
-hydrocortisone & prednisone 5-aminosalicylates - sulfasalazine - olsalazine mab to TNFa - infliximab cytotoxic - azathioprine & mercaptopurine |
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hydrocortison & prednisone
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glucocorticoids
anti-inflammatory tx IBD |
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sulfasalazine
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5-ASA
tx IBD azo bond |
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olsalazine
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5-ASA
tx IBD diazo bond |
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infliximab
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mab to TNFa
tx IBD |
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azathioprine
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cytotoxic agent
tx IBD |
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prokinetc drugs --
most undergo hepatic metab EXCEPT? |
metoclopramide -- unchanged in kidney
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are prokinetic drugs given orally?
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yes, mostly
although metoclopramine, ondansetron & granisetran can be IV |
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prokinetic
absorption? 1/2 life? metab? |
50-80% absorbed from gut
1/2 life = 2-10 hours hepatic metab EXCEPT metoclopramide -- excreted unchanged by kidney |
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why would you use a prokinetic drug?
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-increase gastric tone
constrict sphincters or contract sm m diabetic gastroparesis GERD -N/V relief due to antineoplastic therapy ondansetron & granisetron most effective |
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laxatives
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-secretory or stimulant (castor oil)
-saline (milk of magnesia) -emollient (mineral oil) -bulk-forming (psyllium) |
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what is advantage and disadvantage of saline laxative?
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adv: rapid onset <3 hrs
disadv: explosive diarrhea (always a downer) |
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what are the safest and preferred laxative?
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bulk-forming
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side effect time!
secretory/stimulant? saline? mineral oil? |
secretory/stimulant? electrolyte imbalance
saline? Mg absorption - rectal sloughing mineral oil? decr abs fat-sol vitamins & pulmonary aspiration |
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antidiarrheals
compare the absorption and metab of loperamide vs diphenoxylate |
loperamide vs diphenoxylate
poor vs 90% biliary vs hepatic does not vs CROSSES BBB diphenoxylate = euphoria 1/2 life - 12 hrs |
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discuss abuse of diphenoxylate
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systemic absorption = euphoria
atropine added to reduce abuse potential high dose = resp depression = reverable with NALOXONE metabolized to DIFENOXIN = active metabolite 200-400x more potent than diphenoxylate alone |
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antiemetics
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-5-HT3 antags
-D2 antags -THC agonist -H1 antag -muscarinic antag |
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which antiemetic class has few severe side effects, (anaphylactic rx)
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5HT3 antags:
ondansetron & granisetron anaphylactic rx in ondansetron |
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which antiemetic class has EPS & hyperprolactinemia as side effects?
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D2 antagonist
metoclopramide & prochlorperazine |
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THC drug?
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dronabinol
chemo-induced emesis appetite stimulation in AIDS |
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what classes of antiemetics are used in motion sickness?
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H1 antagonists
dimenhydrinate & meclizine atropine-like muscarinic antag scopolamine |
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osudo question: (?)
best tx for H.pylori? |
Amoxicillin, Tetracycline, and Lansoprazole
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drug class with adv effects:
EPS & hyperprolactinemia |
D2 antagonists
metoclopramide procholorperazine |
