GI Drugs (Quelle) Flashcards
most effective and first line treatment for hyperacidity and ulcers, these drugs are enteric coated to prevent their activation in the gastric lumen, and are absorbed in the blood for delivery to parietal cells
proton pump inhbitors (omeprazole, lansoprazole)
which of the following statements regarding PPIs is FALSE?
A. PPIs have few side effects, which include nausea, abdominal pain and diarrhea
B. PPIs typically lower acid secretion by 90%
C. PPIs quickly inactivate all proton prumps in the parietal cells, which is why one dose is usually effective in clearing symptoms of reflux
D. PPIs are cleared through the liver
E. PPIs interfere with CYP activity, and may increase warfarin concentrations and decrease efficacy of the blood thinner clopidogrel
C. Not all proton pumps are active at any one time, and only those that are active react with these drugs. That is why treatment requires 2-5 days.
these drugs block the base level of acid secretion maintained by ECL cells and are excreted by the kidneys
H2 receptor antagonists
long term use of this H2 receptor antagonist at high doses may cause galactorrhea in women and decreased sperm count, impotence and gynecomastia in men
cimetidine
synthetic analog of PGE1 that can reduce acid secretion up to 90% but because of its very short half life, it is primarily used to prevent NSAID-induced injury
misoprostol
treatment for stress ulcers that forms a sticky neutral pH polymer coating which swells and covers the gastric epithelium
sucralfate; can block absorption of other drugs through the stomach
fast-acting treatment that neutralizes gastric contents for about 2-3 hours
antacids; Al(OH)3, Mg(OH)2, CaCO3
most preparations combine Mg and Al because they have opposing effects (Mg stimulates emptying and motility while Al delays it; this is helpful in combatting constipation/diarrhea)
a general adverse effect associated with acid reducers/blockers is _____ acidity, caused by increased gastrin production that stimulates H+ secretion when the blocking agent is removed
rebound
Which of the following is NOT an adverse effect associated with antacid use? A. Constipation and nausea B. Osteoporosis and encephalopathy C. Hypocalcemia D. Renal failure E. Drug-drug interactions
C. In using CaCO3, hypercalcemia is a transient side effect in normal patients. Al+3 may cause A, B and D.
drug that antagonizes the M1 receptors on ganglion nerves, reducing vagal stimulation of parietal and ECL cells (rarely used because of significant anticholinergic effects)
pirenzepine
These prokinetic agents stimulate enterochromaffin cells to release serotonin, which stimulates primary afferent neurons in the mucosa, which cause contraction and relaxation of the longitudinal smooth muscle of the GI tract (peristalsis)
serotonin (5-HT4) receptor agonists: tegaserod and cisapride
what is the main severe adverse effect associated with serotonin receptor agonists?
fatal cardiac arrythmias; these drugs are not first line, and are in fact only available through restricted distribution programs
why is the approach of simply activating muscarinic receptors (ie, bethanechol, neostigmine methylfulfate) to promote prokinetic activity in the bowel not as effective?
does not mimic the coordinated motiliy of peristalsis
how do dopamine antagonists work?
they block the DA receptor, which leads to increased release of AcH and increased contractility (prokinetic agents)
this dopamine antagonist is used in dysmotility syndromes and also as an antiemetic; side effects include dystonias, parkonsonian symptoms, tardive dyskinesia, etc.
metoclopramide; used for chemo induced nausea
prokinetic agonists that stimulate motility as well as GI secretions, but are not recommended for chronic use
motillin agonists; examples include erythromycin, clarithromycin, azithromycin, which are all macrolide antibiotics
_____ laxatives, such as polyethylene glycol, lactulose and magnesium hydroxide, are non absorbable agents that cause water retention; they act as laxatives at low doses and cathartics at high doses
osmotic; salts (ie, anything with Mg or Na) should be avoided in individuals with renal insufficiency, cardiac disease, electrolyte abnormalities, or with diuretic use
these laxatives are surfactants that allow the mixing of fatty substances with water; are effective as stool softeners but do not increase frequency of defecation
docusate salts
____ laxatives are used orally or rectally and induce mild inflammation leading to reduced water absoprtion and increased motility; generally safe but overdose causes catharsis
irritant (do not chew)
fiber based laxatives that stimulate peristalsis/mass action of soft well-formed stools, and include methylcellulose, psyllium, and polycarbophil
bulk forming laxatives; may exacerbate intestinal obstructions
this bulk forming agent, which can be used as a laxative, is also used as an antidiarrheal for symptomatic relief of watery stools
polycarbophil
antidiarrheal agents that may have CNS effects and are packaged with sub-therapeutic doses of atropine to discourage abuse
opioids (ie, diphenoxylate, difenoxin)
antidiarrheal that is an orally administered opioid agonist, has no CNS effects, and is 40-50 times more potent than morphine
loperamide
Which of the following statements regarding the antidiarrehal agent octreotide is FALSE?
A. It is a peptide derivative of somatostatin that is used to combat secretory diarrhea of hormone secreting tumors
B. May be used for post-surgical gastric dumping syndrome
C. Should be avoided in patients with pancreatitis, as it can cause further inflammation
D. Long term therapy may result in gallstones
E. Adverse reactions include nausea, bloating, and injection site pain
C. Octreotide is actually indicated for pancreatitis, because it reduces secretory acitivity of the pancreas, which is driving its own inflammatory process, allowing it to rest.
antidiarrheal agent that is 99% unabsorbed and eliminated in the feces, has anti-secretory, anti-inflammatory and anti-microbial acitivites, and is commonly included in h. pylori treatments
bismuth
Which of the following statements regarding irritable bowel syndrome (IBS) is FALSE?
A. Alosetron is a 5-HT3 antagonist used for its prokinetic effect on constipation predominant IBS
B. IBS is characterized by chronic abdominal pain and bloating with alternating constipation/diarrhea
C. IBS is a poorly understood non-inflammatory bowel disorder
D. Neither Alosetron nor the 5-HT4 agonist Tegaserod are first line remedies for IBS, and should only be used after other therapies have failed
E. Alosetron may reduce visceral sensitivity by reducing sensory and vagal nerve signaling
A. Alosetron is used primary for diarrhea predominant IBS. Tegaserod is the prokinetic agonist used for constipation predominant IBS.
this class of drugs that includes 5-HT3 antagonists (ondansetron), dopamine receptor antagonists (metoclopramide) and more specific D2 receptor antagonists (prochlorperazine - useful for motion sickness)
antiemetics
class of antiemetics that act mainly on the brainstem and are widely used for motion sickness (work best prophylactically); they are sometimes used for post-operative emesis, though not as often as the 5-HT3 antagonists
antihistamines (H1 antagonists): diphenhydramine, cyclizine, promethazine, hydroxyzine
antihistamine that has anticholinergic effects and can be used for patients with abdominal cancer
cyclizine
