Mechanisms of Action Flashcards
cimetidine (Tagamet)
H2 receptor antagonist; high potential for drug interactions, so mostly replaced by ranitidine and famotidine; used to treat certain allergic reactions
sucralfate
Binds directly to the surface of an ulcer (“ulcer band-aid”). The acid dissociates sucralfate into aluminum hydroxide (an antacid) and sulfate anions, stimulating secretion of mucus and bicarbonate and creating a protective barrier over the ulcers/erosions
diphenoxylate with atropine
acts on smooth muscle of the intestinal tract, inhibiting motility and excessive GI propulsion; contraindicated with pseudomembranous colitis or toxigenic bacteria (the atropine is added to discourage use as a recreational opiate drug)
loperamide (Imodium A-D)
inhibits peristalsis in the intestinal wall and intestinal secretion; only opiate OTC available
psyllium (Metamucil)
bulk-forming laxative; from the dried seed of Plantago psyllium plant; contraindicated in patients with abdominal pain and/or n/v
ducosate salts (Ca++ and Na+) (Colace)
stool-softening emollient laxative; facilitates the passage of water and lipids into the fecal mass; lowers surface tension of GI fluids
glycerin
mild hyperosmotic laxative; increases osmotic pressure in the intestine, drawing fluid into the colon; increases fecal water content resulting in distention, increased peristalsis, and evacuation; often used for children
meclizine (Antivert)
antihistamine used to treat dizziness, vertigo, and nausea; binds primarily to H1 receptors, but also has anticholinergic effects (antisecretory and antispasmodic), preventing cholinergic stimulation of vestibular and reticular systems (cause of nausea)
metoclopramide (Reglan)
prokinetic drug: blocks dopamine receptors in the chemoreceptor triggering zone (CTZ), desensitizing the CTZ to impulses from the GI tract; enhances gastric emptying
ondansetron (Zofran)
serotonin blocker; blocks serotonin receptors in the GI tract, CTZ, and vomiting center; used in treatment of n/v associated with chemotherapy and pregnancy (hyperemesis gravidarum)
Vitamin A (retinol) (Aquasol A)
essential for normal cell growth and differentiation; involved in the growth and development of bones and teeth and in other processes such as reproduction, maintenance/integrity of mucosal and epithelial surfaces, and cholesterol/steroid synthesis
vitamin d3, calcifediol (Calderol)
used for management of hypocalcemia in patients undergoing hemodialysis and for signs of hyperparathyroidism
vitamin d3, calcitriol (Rocaltrol)
used for management of hypocalcemia in patients undergoing hemodialysis; in treatment of hypoparathyroidism, pseudohypoparathyroidism, vitamin D-dependent rickets, and hypocalcemia in premature infants
vitamin E (Aquasol E)
powerful biologic antioxidant; deficiency may result in irritability, edema, thrombosis, and hemolytic anemia
vitamin K, phytonadione (AquaMEPHYTON)
facilitates biosynthesis of clotting factors; deficiency results in hypoprothrombinemia; deficiency is rare because intestinal flora are normally able to synthesize sufficient amounts
vitamin B1, thiamine
required for the citric acid cycle (Krebs), a major part of carbohydrate metabolism; also plays a role in the integrity of the peripheral nervous sytem, CV system, and GI tract
vitamin b2, riboflavin
converted into two enzymes that are essential for tissue respiration; plays important part in carbohydrate catabolism; needed for activation of b6; needed for conversion of tryptophan into b3 and maintenance of erythrocyte integrity
vitamin b3, niacin
required for carbohydrate, protein, purine, and lipid metabolism and tissue respiration; also used for antilipemic effect
vitamin b6, pyridoxine
necessary for protein, carbohydrate, and lipid metabolism and conversion of tryptophan to niacin; essential in synthesis of gamma-aminobutyric acid (GABA) and heme, therefore necessary for integrity of peripheral nerves, skin, and mucous membranes
vitamin b12, cyanocobalamin
required for nucleoprotein and myelin synthesis, cell reproduction, normal growth, and maintenance of normal erythropoiesis
vitamin C, ascorbic acid
required for collagen synthesis, maintenance of connective tissue; tissue repair; maintenance of bone, teeth, and capillaries; folic acid metabolism; erythropoiesus; synthesis of lipids, proteins, and steroids; enhances absorption of iron
calcium
involved in proper development and maintenance of teeth and skeletal bones; catalyst in many of the coagulation pathways in the blood; cofactor in clotting reactions and conversion of prothrombin to thrombin and fibrinogen to fibrin; essential for the maintenance & function of nervous, muscular, & skeletal systems; transmission of nerve impulses and muscle contractions; release and storage of neurotransmitters and hormones, uptake and binding of amino acids, and in intestinal absorption of cyanocobalamin
magnesium
known cofactor for many enzyme systems; required for muscle contraction and nerve function; produces an anticonvulsant effect by inhibiting neuromuscular transmission
phosphorus
precursor for the synthesis of essential body chemicals; important building block for body structures; structural unit for synthesis of nucleic acids, ADP, and ATP; necessary for the development of skeletal system and teeth (bones contain 85% of phosphorus in body)
ketoconazole
antifungal- DO NOT take with H2 antagonists
omeprazole (Prilosec)
proton pump inhibitor; binds to the hydrogen-potassium-ATPase pump (proton pump), preventing movement of hydrogen ions out of parietal cells into the stomach. Prevents more than 90% of acid secretion over 24 hours.
antacids, general
neutralize gastric acidity; stimulate secretions of mucus, prostaglandins, and bicarbonate
antacids, Mg++ and Ca++ based
avoided in patients with real disease, due to possible toxicity
antacids, Mg++
commonly have a laxative effect and can rarely be tolerated alone
antacids, Al+++
Can lead to constipation
antacids, Al+++ and Na+ based
recommended for patients with renal compromise because they are more easily excreted
bismuth subsalicylate (Pepto Bismol)
adsorpent drug; coats the walls of the GI tract, attracting the toxins/bacteria to its surface for elimination from the body; form of aspirin
magnesium hydroxide (Milk of Magnesia)
hyperosmotic laxative; increases osmotic pressure in the small intestine by inhibiting water absorption; very potent
methylcellulose (Citrucel)
bulk forming laxative; attracts water into the intestine and absorbs excess water into the stool, stimulating the intestines and increasing peristalsis; contraindicated in GI obstruction and hepatitis
belladonna alkaloid (Donnatal)
anticholinergic used for antidiarrheal; slows peristalsis, reduces gastric secretions, and has a drying effect; used in combination with opioids and adsorbents
scopolamine
anticholinergic used for antiemesis; binds to ACh receptors in the vestibular nuclei (deep in the brain); nausea-inducing signals are then blocked from being transmitted to the CTZ; also blocks signals between the reticular formation and the vomiting center
dronabinol (Marinol)
only commercially available THC; has inhibitory effects on the thalamus, reticular formation, and cerebral cortex; also stimulates appetite in AIDS/ cancer patients
feverfew
member of the marigold family; antiinflammatory properties; treatment of migraines, menstrual cramps, inflammation, and fever; adverse effects: n/v, constipation, diarrhea, muscle stiffness/joint pain, altered taste
echinacea
immunostimulant effects; promotion of healing wounds; reduces cold symptoms/recovery time; antisepsis; treatment of viral infections and flu-like respiratory infections, and chronic ulcerations
lactobacillus (Bacid)
probiotic; acid-producing bacteria; used for treatment in uncomplicated diarrhea, particularly in that caused by antibiotic therapy
garlic (allium sativum)
active ingredient: allicin; antispasmodic, antiseptic, antibacterial, and antiviral; antihypertensive; antiplatelet; lipid reducer
treatment options for Helicobacter pylori
1st line: 10-14 day course of proton pump inhibitor and antibiotics clarithyromycin and either amoxicillin or metronidazole OR combo of proton pump inhibitor with bismuth subsalicylate and antibiotics tetracycline and metronidazole
H2 receptor antagonists
blocks H2 receptor of parietal cells, decreasing the response to histamine and the stimulation of ACh & gastrin (blocks up to 90% of vagal- and gastrin-stimulated acid secretion
