Gastro Flashcards
What do a majority of antacids contain either alone or in combination?
Calcium carbonate
What is the onset and duration of action for antacids?
<5 minutes
20-30 minutes
What are the side effects for calcium carbonate?
Constipation/flatulance
What are the interactions to consider with calcium?
Lilly of the Valley
Strophanthus
What antacid can cause diarrhea?
Mg
MOA for H2RA’s?
Block type 2 histamine receptors located on the parietal cells which prevents stimulation of proton pump
What are four main H2RA’s?
Famotidine (pepcid)
Ranitidine (zantac)
Cimetidine (tagamet HB)
Nizatidine (Axid AR)
What is the onset and duration for H2RA’s?
30-45 min
4-10 hours
What are the side effects of H2RA’s?
Anti-androgenic arrhythmias H/A Dizziness GI
What are the interactions to avoid with H2RA’s?
Caffeine, St. John’s Wort
Which H2RA is know for it’s interactions?
Cimetidine (cytochrome P450 system)
MOA of PPIs?
Selective, irreversible H/K/ATPase inhibition on luminal side of parietal cells
What is the onset and duration of PPIs?
2-3 hours
24 hours
What are the five main PPIs?
Omeprazole (Prilosec) Esomeprazole (Nexium) Lansoprazole (Prevacid) Pantoprazole (Protonix) Rabeprazole (Aciphex)
What does it mean that PPIs are ‘acid-labile’?
They are broken down in the presence of stomach acid, which reduces their absorption. Therefore, it is recommended to take 30 minutes before eating.
What are the PPI side effects?
Mg depletion Osteoporosis C. diff infection CA pneumonia, HA/dizziness
What are interactions to consider with PPIs?
Grapefruit and St. John’s Wort
Simethicone MOA?
Inert silicone polymer, “de-foaming” agent; reduces surface tension of gas bubbles
Activated charcoal MOA?
Highly absorptive; possible adsorbent effect
(“Adsorption is a process that occurs when a gas or liquid accumulates on the surface of a solid or, more rarely, a liquid forming a molecular or atomic film. It is different from absorption, in which a substance diffuses into a liquid or solid to form a solution.”)
Alpha-Galactosidase MOA?
A mold-derived enzyme, cleaves oligosaccharides before reaching colonic bacteria
(recommended for gas prevention with high-fiber diets)
Avoid with DM and galactosemia
Senna MOA?
Anthraquinone stimulates peristaltic activity on the intestine
Distinguishing side effect of Senna?
Melanosis coli
Bisacodyl MOA?
Stimulates peristalsis by directly irritating the SM of the intestine
Distinguishing side effect of Bisacodyl?
Electrolyte disturbances
Polyethylene glycol MOA?
Osmotic laxative
Magnesium citrate MOA?
Osmotic laxative
Docusate MOA?
Dioctyl sodium sulfosuccinate reduces surface tension of the oil-water interface of the stool allowing oil and water to be incorporated.
Psyllium MOA?
Soluble fiber, absorbs water in the intestine > viscous liquid > promotes peristalsis and reduces transit time
What is used to reverse opioid induced constipation?
Opiate receptor antagonists
Loperamide MOA?
Decreases GI motility by effects on the circular and longitudinal muscles. Reduces GI secretions produced by OPIOID RECEPTOR BINDING EFFECTS IN THE INTESTINAL MUCOSA.
What are the potential interactions with loperamide?
Henbane, scopolia, st. john’s wort
Can loperamide use lead to dependence and abuse?
Yep
Diphenoxylate and atropine MOA?
Opiate receptor agonist (inhibits excessive GI motility)
OTC forms contain subtherapeutic doses of atropine to discourage abuse
What are the four pharmacologic interventions used for IBD?
Corticosteroids/glucocorticoids
Aminosalicylates
Immunosuppressants
Antibiotics
Corticosteroid (prednisone) MOA?
Modulates protein synthesis > reduced migration of PMN and fibroblasts.
Reverses capillary permeability and lysosomal stabilization at the cellular level to prevent or control inflammation.
Immunosuppression
What makes glucocorticoids and mineralocorticoids different from corticosteroids?
Receptor affinities
What is the advantage of budesonide (a glucocorticoid)?
Utilizes the release mechanism of enteric-coated tablets and capsules that delay release until pH > 5.5. (has good topical activity with low systemic bioavailability)
Mesalamine (aminosalicylate) MOA?
Modulates local chemical mediators of the inflammatory response, particularly leukotrienes, and acts as a free radical scavenger or inhibitor of TNF.
Sulfasalazine (aminosalicylate) MOA?
Prodrug of mesalamine. The azo bond is cleaved by colonic bacteria.
What supplement should patients on sulfasalazine take?
It inhibits the absorption of dietary folate, which should be supplemented between meals.
Azathioprine (antimetabolite) MOA?
Inhibits purine synthesis and DNA replication > anti-proliferative effect and induction of apoptosis of T-cells.
(prodrug that be is converted to 6-mercaptopurine)
TNF-alpha monoclonal antibodies MOA?
Inhibits TNF-alpha (which is responsible for induction of proinflammatory cytokines) > enhancement of leukocyte migration, activation of neutrophils and eosinophils, and the induction of acute phase reactants and tissue degrading enzymes.
Infliximab (anti-TNF-alpha) MOA?
Chimeric IgGk that binds to both free and membrane bound TNF-alpha
Adalimumab (anti-TNF-alpha) MOA?
Human mAb against TNF-alpha
Ondansetron MOA?
Selectively antagonizes serotonin at 5-HT3 receptors, both peripherally on vagal nerve terminals and centrally in the chemoreceptor trigger zone.
Promethazine MOA?
Blocks postsynaptic mesolimbic dopaminergic receptors (alpha-adrenergic blocking effect and depresses the release of hypothalamic and hypophyseal hormones)
Metoclopramide MOA?
Antagonizes dopamine receptors and at high doses blocks serotonin receptors in chemoreceptor trigger zones of the CNS
What is the prokinetic mechanisms of metoclopramide?
Enhances the response of Ach in upper GI tract causing enhanced motility and accelerated gastric emptying without stimulating gastric, biliary, or pancreatic secretions
