GI pharm: esophagus, stomach, and duodenum Flashcards
What antacids are used for the tx of ulcers?
- aluminum salts
- magnesium hydroxide
- calcium carbonate
MOA of antacids?
-tx of ulcers
work by neutralizing gastric acid
- protect gastric mucosa against acute chemical injury
- bind bile acids and inhibit peptic activity
- promote angiogenesis in injured mucosa
- heavy metals suppress H. pylori
Antacids drug interactions?
- variety of drug interactions
- can bind with drugs taken at same time decreasing absorption of that agent
- interact w/ many abx
Magnesium salts - names, SEs, caution?
- magnesium hydroxide/aluminum hydroxide
- brand names: Maalox, alamag, Mag-A1, Mag-A1 ultimate, mylanta
- common side effects: diarrhea, constipation, abd cramps, N/V, hypermagnesemia
- caution with renal insufficiency!!!!
Aluminum salts - caution, names?
- caution in renal insufficiency
- can block the intestinal absorption of phosphate
- names:
acid gone
gaviscon
Calcium carbonate - names, indications, most common side effects, special instructions?
- tums, maalox regular chewable, cclci-chew, rolaids, chooz, alka-mints
- indications: acid indigestion, heartburn
- most common side effects: constipation, bloating, gas, N/V, abdominal pain, xerostomia
- separate from other meds by 2 hrs
Name the H2 blockers?
- cimetidine (tagamet)
- ranitidine (zantac)
- famotidine (pepcid)
- nizatidine (axid)
indications for H2 blockers?
- tx and maintenance therapy of PUD
- tx of GERD
- management of dyspepsi
MOA of H2 blockers?
- inhibit acid secretion by blocking histamine H2 receptors on parietal cell
- generally dosed to take 30-60 min prior to a meal (if using for acid suppression with meals)
SEs of H2 blockers?
- rare, severe adverse effects, such as renal and hepatotoxicity
- myelosuppresison:
thrombocytopenia
neutropenia
anemia
pancytopenia
Rare CNS SEs from H2 blockers?
- can cause confusion, restlessness, somnolence, agitation, HAs, dizziness, with prolonged therapy: hallucinations, focal twitching, seizures, unresponsiveness, and apnea (primarily in elderly with concomitant RENAL and/or hepatic failure)
Rare cardiac SEs from H2 blockers?
- sinus bradycardia
- hypotension
- AV block
- prolong. QT interval
- sinus and cardiac arrest have occured with rapid infusion
SEs of cimetidine? Should you use it?
- can rarely cause gynecomastia and impotence
- polymyositis
- interstitial nephritis
- cleared through P450 system so has mult drug interactions
- giving rapidly IV can cause cardiac arrhythmias and hypotension
Absorption and distribution of H2 blockers?
- well absorbed after oral dosing
- peak serum concentrations occur within 1-3 hrs
- absorption is reduced by 10-20% if taken with antacids
- don’t give acid suppression therapy together: will actually decrease efficacy of drugs
Class of PPIs?
- omeprazole (prilosec, zegrid)
- lansoprazole (prevacid)
- pantoprazole (protonix)
- esomeprazole (nexium)
- dexlansoprazole (kapidex)
- rabeprazole (AcipHex)
- all have the same efficacy
Indications for PPIs?
tx of all acid related conditions:
- PUD
- GERD
- zollinger-ellison syndrome
- tx and preventing NSAID assoc gastroduodenal mucosal injury
- eradication of H. pylori infection
MOA of PPIs?
- block acid secretion:
irreversibly binds to and inhibits the H-K ATPase pump on parietal cell membrane - parietal cells need to be active for PPIs to work so don’t give other antisecretory meds at same time
- the amt of H-K ATPase present in parietal cell is greatest after a prolonged fast, PPIs should be admin b/f first meal of the day
- if on long term therapy- need to taper off
- anticholinergics will decrease efficacy of PPI
Onset of action for a PPI?
- about an hour
- peak concentration in about 2 hrs
SEs of PPIs?
- diarrhea
- HA
- flatulence with protonix
Drug interactions with PPIs? Which one has the least?
- pantoprazole (protonix): lowest potential for P450 drug interactions
- omeprazole (prilosec, zegrid) and esomeprazole (nexium): metabolized largely by CYP2C19 and the potential for interactions thus appears to be greatest among PPIs
(omeprazole is supposed to be more powerful, probably isn’t)
What drug does omeprazole have a significant interaction with? BBW
- clopidogrel (plavix)
- decreases efficacy of antiplatelet action of clopidogrel - increased risk of clotting
What other drugs do omeprazole have interactions with?
- warfarin
- diazepam
- phenytoin
- theophylline
- digoxin
- carbamazepine
Long term admin of PPIs ma increase the incdience of?
- infections: C diff, pneumonia
- fractures: hip, wrist, spine
- malabsorption of:
B12 (check levels)
magnesium (check levels esp with diuretics and digoxin admin) - iron
- if person is anemic, ask about PPI use
Admin of PPIs?
- takes 30-60 min b/f first meal of the day
- if 2x daily dosing is needed then take 2nd dose 30-60 min prior to last meal of the day