Week 13: GI Meds Flashcards
Prototype GI Meds
14:
Famotidine Omeprazole Sucralfate AlOH and MgOH Simethicone Dimenhydrinate Promethazine Metoclopramide Ondansetron MgOH Bisacodyl Psyllium Docusate Loperamide
Famotidine (Pepcid) Classification
Antihistamine (H2 Blocking Agent)
different from H1 receptor blockers like true antihistamines
Action of Famotidine
Competitive antagonist acting on H2 receptors and mediates parietal cell acid production
Inhibits vagal stimulated gastrin enzyme release
*Basically blocks histamine action at parietal cells in the stomach to stop acid secretion
Routes for Famotidine
Oral or Parenteral
ADRs of Famotidine
UNCOMMON! (w/ short term use)
CONFUSION (Can see in older individuals since H2 is blocked)
PNEUMONIA
Other: HA, tiredness, constipation
Why is pneumonia a potential ADR of famotidine
because increasing gastric pH means organisms that are killed off normally can be aspirated
How often is famotidine given for GERD
20-40 mg TWICE DAILY
What does the suffix “-idine” mean
H2 blocker
Omeprazole (Prilosec) Classification
Proton Pump Inhibitor (PPI), gastric acid secretion suppressent
(Suppresses acid production)
Action of omeprazole
a “prodrug” converted to active form in parietal cells
active form inhibits H+K+-ATPase (enzyme producing gastric acid)
ADRs of omeprazole
Short Term Use (4-8 weeks): HA, NVD
Long Term: CHRONIC KIDNEY DISEASE, Dementia, Mg Deficiency, Pneumonia, Weakened Bones (Ca absorption)
What is considered to be one of the most effect acid secretion suppression drugs? What is the issue with it
Omeprazole
the issue is the ADRs increase with long term use such as chronic kidney disease
What is the most effective class of drugs for suppressing gastric acid secretion
PPIs (ex: omeprazole)
What does the suffix “-prazole” mean
PPI (ex: Omeprazole, Protonix is Pantoprazole)
What is important to know aboutb the tablet of Prilosec/omeprazole
it is enterically coated in a delayed release capsule so do not crush it
Sucralfate (Carafate) Classification
Anti Ulcer
What is unique about sucralfate
it is a unique drug with no other drug being like it
It “patches” the ulcerated area in the stomach mucosa
Action of sucralfate
exact mechanisms not fully defined
exerts LOCA ACTION - forms an ULCER ADHERENT COMPLEX (gooey sticky patch) at the ulcer site to protect it against further acid attack, pepsin, or bile salts
Also inhibits pepsin activity
Where does sucralfate act
acts locally (on the GI tract) not the bloodstream by patching the ulceration on mucosa
Sucralfate must be given…
on an empty stomach
What is important to know about the absorption and distribution of sucralfate
only 3-5% is absorbed since it has local low absorption
It is distributed on the GI tract and lasts about 5 hours
ADRs of Sucralfate
Most Common: CONSTIPATION
Other: Diarrhea, Nausea, Gastric Discomfort, Indigestion, Dry Mouth, Rash, Pruritis, Back Pain, Dizziness, Vertigo
*generally well tolerated)
Why can sucralfate not be given with an antacid within a half an hour period
because the stomach mucosa needs to be pH <4 for activation
sucralfate may interfere with what
absorption of fat soluble vitamins (blocks that mucosa)
Antacids
base salts that increase gastric pH
by doing so, they relieve symptoms of hyperacidity, GERD, and the pain of duodenal ulcers
AlOH & MgOH (Maalox) Classification
Antacid, Non sytemic
When do we give antacids
2 hours after other drugs to prevent interactions
Also given after meals WHEN ACID IS ALREADY PRODUCED
Action of AlOH & MgOH (Maalox)
local activity of neutralization of gastric acid by chemical reaction leading to higher pH
Absorption of AlOH & MgOH (Maalox)
it is not absorbed AT ALL
ADRs of AlOH & MgOH (Maalox)
Aluminum products cause constipation
Magnesium products cause diarrhea
Maalox attempts to balance these two effects out
What is important to know about taking other drugs alongsde AlOH & MgOH (Maalox)
the maalox can reduce absorption of drugs like tetracyclines, digoxin, iron, etc so they are all taken separately from antacids
Simethicone (Mylicon) Classification
anti flatulent
Action of simethicone
alters surface tension of gas bubles - they then coalesce and free the gas through belching or flatus
Disperses and prevents formation of mucus surrounded gas pockets in the GI tract so its easier for the body to expel these big bubbles
In essence what is simethicone doing
it is not PREVENTING gas from being made, it just is finding new ways of epelling it
ADRs of simethicone
VERY WELL TOLERATED
so mild it can be used on infants (can help with colic)
Route of simethicone
oral (80-120 mg qid)
Is simethicone often found in combination with anything else
its often found combined with other GI drugs like antacids
Why is simethicone the last drug you should take
because it works faster in dissolving than other drugs since its pink and chewable
dimenhydrinate (Dramamine) Classification
ANTIEMETIC, Anticholinergic, Antihistamine
What is dimenhydrinate often used for
PREVENTION of motion sickness
Action of dimenhydrinate
decreases GI motility and GI spasm (that usually causes vomiting) due to its anticholinergic action
Some H1 - antihistamine action affect neural labyrinth pathways by competing for receptor sites
ADRs of dimenhydrinate
ANTICHOLINERGIC SE - Dry mouth
Sedation
Blurred vision
Urinary Retention
(slow GI effect)
When should dimenhydrinate be taken
take .5-1 hour before activity like a car ride, boat ride, coaster, etc - it should be on board and working prior for prevention