Lecture 17 - GI Pharmacology Flashcards
Rank the following in order of fastest to slowest acting antacids:
Calcium carbonate
Magnesium or Aluminum Hydroxide
Sodium bicarbonate
Sodium bicarb > Calcium carbonate > Magnesium or Aluminum hydroxide
Of magnesium hydroxide and aluminum hydroxide, which potentially produces diarrhea and which produces constipation?
Magnesium –> diarrhea
Aluminum –> constipation
“-tidine” drugs are ____ receptor blockers. They are rapidly absorbed via small intestine transporters. Except for _____, they undergo hepatic first pass, leaving their bioavailability at about 50%.
H2
Nizatidine
H2 receptor blockers are particularly effective at decreasing ______ (daytime or nocturnal?) acid secretion.
Side effects in men can include ______, while in women can include ______.
Nocturnal
Gynecomastia
Galactorreha
For ethnic groups with ______ defects, taking H2 blockers before ehtanol consumption slows its catabolism to ______ (which otherwise causes flushing). Be careful of using H2 blockers in this way for alcoholics taking _______ –> they may experience acetaldehyde poisoning.
ALDH
Acetaldehyde
Disulfiram
While H2 blockers last about ____ hrs, PPIs (“-prazole”) completely suppress acid secretion for ___hrs.
Keep in mind PPIs are administered as ______ (inactive form). They accumulate in cannaliculi of stimulated _____ cells, where the environment is acidic and can protonate the PPI drugs. Once protonated, they form _____ _____ with cysteine residues of H+/K+ ATPase.
10 hrs
24 hrs
Prodrugs
Parietal cells
Disulfide Bridges
When is the best time to take PPIs and why?
About an hour before a meal –> in a fed state, the bioavailability of PPIs is reduced by about 50% bc presence of food actually buffers the stomach lumen. In a FASTING state, proton pumps are vesicle bound in Parietal cells, so PPIs cannot access them.
Optimal effect of PPIs takes about ___-___ days of continuous use.
3-4 days
For ulcers caused by H. pylori, PPIs are taken in combination with 2 ______.
For NSAID-induced ulcers, PPI + H2 blockers is the recommended treatment if NSAIDs _____ (can or cannot?) be discontinued, while PPIs alone is the recommended treatment if NSAIDs _____ (can or cannot?) be discontinued.
PPIs are also used to treat ______, with the target being to bring acid output to < 10mE/h
Antibiotics
CAN
CANNOT
Gastrinoma
Remember that gastric acid, or low gastric pH, inhibits _____ secreting ____ cells. Thus, chronic use of PPIs causes hyper_______, which causes excess mucosal growth of the GI tract.
Also remember that gastric acid facilitates _____ absorption, so watch for postmenopausal women who are already at higher risk of issues with bone density. Similarly, vegetarians have higher levels of ____ and ____ acid in their diets, which interferes with _____ absorption. Thus, they are at higher risk for HYPO_______.
Gastrin secreting
G-cells
Hypergastrinemia
Ca++
Oxalic
Phytic
Hypocalcemia
_______ is a drug that is metabolized to Sucrose Sulfate in the gastric lumen –> the negatively charged sulfates bind positively charged proteins exposed in ulcers –> so this med selectively binds DAMAGED mucosa, creating a ______ barrier. This is a good alternative to PPIs for hospital patients/those at increased risk for ______ ______.
Sucralfate
Physical
Nosocomial pneumonia
______ compounds, like kaopectate and Pepto-Bismol, bind enterotoxins and have antimicrobial effects. They reduce stool frequency and fluid volume in ______ diarrhea.
Bismuth compounds
Secretory
Misoprostol is a ______ analogue, so it inhibits gastric acid secretion and STIMULATES mucus and _____ secretion, while enhancing blood flow. This is used clinically to treat ulcers caused by ______.
Prostaglandin
HCO3-
NSAIDs
