GI Flashcards
Acid Reducing Drugs
Antacids - Mg and Al hydroxide - CaCO3 - NaHCO3 H2 Antagonists - Ranitidine - Cimetidine - Famotidine - Nizatidine Proton Pump Inhibitors - Omeprazole - Esomeprazole - Lansoprazole - Dexlansoprazole
Antacids
Mechanism: - chemically neutralize acid that is present Short lived Use: - occasional GERD or dyspesia - discriminate chest pain MI vs acid reflux Drugs: MgOH - diarrhea - hyperMg in renal pts AlOH - constipation - hypophosphatemia - decrease drug adsorption CaCO3 - produce CO2 - belching/bloating - constipation - hyperCa - kidney stones - acid rebound NaHCO3 - produce CO2 - belching/bloating - systemic alkalosis in renal pts - fluid retention - Na
H2 antagonists
Mechanism:
- prevent histamine induced activation of H release - block histamine binding H2 receptors on parietal cells, no cAMP production
- decrease proton and pepsin secretion in dose dependent manner
Use:
- heartburn and dyspesia, GERD
- added to PPI for nocturnal breakthrough
- stress ulcer prophylaxis
- peptic ulcer healing and zollinger-ellison syndrome, but prefer PPIs
Tachyphylaxis
Drugs:
Cimetidine
- large doses: inhibits cyp450
- antiandrogenic - gynecomastia and galactorrhea
- cardiovascular problems
- confusion in elderly
Ranitidine
Famotidine
Nizatidine
Proton Pump Inhibitors
Mechanism:
- directly block parietal H-K ATPase to decrease H secretion into lumen, irreversible block
- needs conversion to sulfenamide via acid
Most effective when parietal cells create the most acid - take before meal, preferably before 1st meal of day
Don’t take with H2 blockers cuz need the acid
Use:
- peptic ulcer disease, GERD, reflux esophagitis
- H pylori with abx
- Zollinger Ellison syndrome
- IV form used for upper GI bleed to reduce need for intervention and reduce risk of rebleeding after intervention
Drugs:
Omeprazole
Lansoprazole
Dexlansoprazole
Pantoprazole
Esomeprazole
Adverse events:
- common: headache, abdominal pain, nausea, diarrhea, flatulence
- p450 metabolism so drug interactions (clopidogrel be aware)
- increased risk of GI infxns - check for C diff if pt has diarrhea
- increase risk of fracture
- increased risk of pneumonia
- risk of hypomagnesemia - check Mg levels
Mucosal Protectants
Bismuth Salts
Sucralfate
Misoprostol
Bismuth Salts
Action: - coats ulcers and inflamed areas Use: - gastroenteritis - symptoms of nausea, dyspepsia, diarrhea - traveler's diarrhea prophylaxis Side effects: - black tongue and feces - interactions with anticoagulants
Sucralfate
Action:
- forms temporary coating on ulcers, protects them from acid and digestive enzymes
Take before meals
Use:
- stress ulcer prophylaxis (not much anymore)
- bile reflux gastritis and esophageal ulcers post variceal banding
Misoprostol
Prostaglandin E1 analog Action: - stimulates mucous production - decreases acid secretion Uses: - induces labor - use in pts with chronic NSAID use cuz of ulcer risk with reduced PGE1
GI motility agents
Erythromycin - Abx Cholinomimetics - bethanechol, neostigmine Dopamine receptor antagonists - metoclopramide, domperidone Serotonin - metoclopramide
Erythromycin
Macrolide abx Action: - activates motilin receptors on smooth muscle of antrum and small intestine Use: - diabetic gastroperesis Adverese events: - tachyphylaxis - QT prolongation
Cholinomimetics
Neostigmine, Bethanechol - increase GI motility big time Use: - Ogilive syndrome (IV) Side effects: - cholinergic
Metoclopramide, Domperidone
Dopamine receptor antagonists - pre and post synaptic
Action:
- promote gastric/intestinal motility through Ach release
- increase gastric tone
- improve antroduodenal coordination
- accelerate gastric emptying
Side effects of metoclopramide:
- reversible: somnolence, feeling jittery, headache, diarrhea
- serious side effects: tardive dyskinesia, dystonia, neuroleptic malignant syndrome
Laxatives
Bulk forming - Fiber - psyllium Osmotic Agents - Magnesium salts - polyethylene glycol - Lactulose - PED - milk of magnesia Stimulants - Bisocodyl - Senna - Castor oil - Cascara Stool Softeners - Docusate - Mineral Oil Cl channel secretion - Lubiprostone GC-C agonist - Linaclotide
Psyllium, Polycarbophil
Fiber laxative - Bulk laxatives Action: - form gels in the colon causing water retention and distention - increase peristalsis
Polyethylene glycol, Mg salts, milk of magnesia
Osmotic laxative
Action:
- draw H2O into intestinal lumen via osmosis resulting in softer/liquid stools and distension induced peristalsis
Bisacodyl/Dulcolax, Senna
Stimulant laxative
Action:
- stimulates colonic smooth muscle and causes H2O accumulation in lumen
Docusate
Surfactant
Stool softener - laxative
Action:
- causes fat/H2O to mix
Mineral oil
Lubrictant
Stool softener - laxative
Action:
- prevents H2O absorption by coating stool
Can inhibit absorption of fat-soluble vitamins
Lubiprostone
Cl channel secretion laxative
Action:
- activates ClC-2 chloride channels, chloride secretion, Na follows and water follows
Linaclotide
GC-C agonist laxative
Action:
- binds GC-C receptor, increases cGMP, increases Cl and bicarbonate secretion, therefore water
- activates CFTR
Anti-diarrheal
Do not use if GI infxn or inflammation is present - toxic megacolon Antimotility - Loperamide - Diphenoxylate-atropine - Tincture of opium Absorbents - Bismuth subsalicylate - Fiber - Bile acid binding resins - cholestryramine, colestipol Antisecretory - Octreotide - Somatostatin
Loperamide, Diphenoxylate/atropine, Tincture of Opium
Anti-diarrhea
Antimotility agents - opiates
Action:
- act on opioid receptor in gut
- act directly on circular and longitudinal intestinal muscles
- inhibit peristalsis and prolong transit time of material within gut
- increases viscosity since more time for contact
- diminishes fluid and electrolyte loss
- increases anal sphincter tone
Caution:
- do not combine loperamide and tincutre of opium with other CNS depressants cuz sedation and respiratory depression
Bismuth busalicyclate
Anti-diarrhea Absorbent - anti-secretory - anti-microbial - anti-inflammatory Caution: - salicylate, so do not use with aspirin or anticoagulants cuz of blood thinning effect - reye syndrome - do not use with viral infxn in children
Fiber
Anti-diarrhea
Bulking agent - stool regulator
Action:
- absorbs intraluminla water and improves consistency of diarrhea
Cholestryramine, Colestipol
Anti-diarrhea
Bile acid binding resins
Action:
- form non-absorbable complex with bile acids
- bile acids stimulate colonic secretion, causing secretory diarrhea
- bile acids absorbed in terminal ileum
Caution:
- seperate from other meds by 2 hrs cuz binds them
Ocreotide/somatostatin
Anti-diarrhea
Antisecretory agent
Action:
- reduces fluid and electrolyte secretion by stomach and pancreas
- mild antimolity effect
- promotes intestinal electrolyte absorption
- suppresses neuroendocrine tumor release of peptides that cause intestinal hypersecretion of electrolytes and water
Anti-nausea and emesis
Anticholinergic - scopolamine Antihistamine - meclizine, dimenhydrinate DA antagonist - prochlorperazine, promethazine 5HT antagonist - ondansetron, dolasetron, granisetron Cannabinoid - dronabinol Neurokinin antagonist - aprepitant
Scopolamine
Antiemetic Anticholinergic Action: - blocks Ach at M1 receptor Use: - prevents motion sickness - prevents chemo induced nausea Side effects: - anticholinergic: dry mouth, sedation, blurred vision, confusion, urinary retention
Meclizine, Dimenhydrinate
Antiemetic
Antihistamine
Action:
- block H1 and has anticholinergic effects
Use:
- tx motion sickness
- hyperemesis gravidarum
Side effects:
- sedating; meclizine less than dimenhydrinate
- anticholinergic: dry mouth, sedation, blurred vision, confusion, urinary retention
Promethazine, Prochlorperazine
Antiemetic DA antagonist Action: - D2 receptor blocker, some anticholinergic effects Use: - prophylaxis preop; postop - motion sickness - toxic and metabolic induced nausea - migraine related nausea - hyperemesis gravidarum Side effects: - anticholinergic: dry mouth, sedation, blurred vision, confusion, urinary retention - sedation - extrapyramidal - tardive dyskinesia, pseudo-parkinsonism, acute dystonia - QT prolongation
Ondansetron, Dolasetron, Granisetron
Antiemetic 5HT antagonist Action: - act on vagal nerve terminals and chemoreceptor trigger zone, antagonize serotonin receptors Use: - multiple settings for antiemesis - chemotherapy induced nausea/vomit - migraine related nausea - postop nausea/vomit - hyperemesis gravidarum Side effects: - QT prolongation
Dronabinol (delta 9 THC)
Antiemetic Cannabinoid Action: - agonize CB1 receptor Use: - chemo induced nausea vomit - appetite stimulant in AIDS/HIV Side effects: - euphoria, paranoia, CNS depression, abuse potential
Aprepitant, Fosaprepitant
Antiemtic NK antagonist Action: - substance P/neurokinin I receptor antagonist Use: - prevention of acute and delayed chemo induced and post-op nausea/vomit - give before chemo or anesthesia Adverse events: - hiccups - fatigue - increased risk of infxn
Anti-inflammatories
Aminosalicylates
- sulfasalazine, mesalamine, balsalazide, olsalazine
Glucocorticoids
- prednisone, methylprednisolone, budesonide
Immunomodulators
- methotrexate, 6MP/azathioprine
Biologics
- infliximab, adalimumab, certolizumab, natalizumab
Mesalamine, Balsalazide, Olsalazine
5-Aminosalicylates Anti-inflammatory Active in colon 5-ASA is active component Use: UC and Crohn's Adverse events: - mild GI and headache occasionally - hypersensitivity rxns - pancreatitis, pneumonitis - paradoxical worsening of disease - chronic interstitial nephritis
Sulfasalazine
Aminosalicylate Anti-inflammatory Prodrug release in colon Use: UC and Crohn's Adverse events: - frequent GI (N/V), CNS and hematologic side effects - megaloblastic anemia, leukopenia - agranulocytosis - monitor for this - decreased folic acid absorption - treat with folic acid
Prednisone, methylprednisolone
Glucocorticoid Use: - induce remission in both UC and Crohn's - not maintenance - must be tapered off Adverse events: - muscle wasting - lipodystrophy - buffalo hump, abdominal fat - thinning of skin - moon facies - HTN - poor wound healing - osteoporosis - hyperglycemia - increased suspectibility to infxn
Budesonide
Non-systemic glucocorticoid - controlled ileal or colonic release High first pass metabolism in liver Use: - induction for Crohn's and UC - requires taper Smaller pts get more systemic effects Adverse events: - muscle wasting - lipodystrophy - buffalo hump, abdominal fat - thinning of skin - moon facies - HTN - poor wound healing - osteoporosis - hyperglycemia - increased suspectibility to infxn
6-MP, Azathiopurine
Purine antimetabolites
- 6MP metabolized by TPMT, HPRT, and xanthine oxidase
- HPRT to 6TGN - active metabolite
- TPMT to 6-MMP - inactive metabolite
Action:
- inhibits nucleotide synthesis, decreases lymphocytes, decreases pro-inflammatory cytokine production
Use:
- maintenance of remssion in UC and Crohn’s; 3 mo to reach therapeutic levels
Adverse events:
- leukopenia, thrombocytopenia from 6-TGN
- hepatotoxicity from 6-MMP
- infxn risk increased
- increased risk of malignancy
- avoid use with allopurinol
Methotrexate
Immunomodulator - folate anti-metabolite - inhibits dihydrofolate reductase - results in apoptosis of T cells Use: - maintenance of remission in Crohn's Adverse events: - hepatotoxicity - myelosuppression - interstitial lung disease - mucositis - teratogenic Give folic acid to all pts
anti-TNFa
mAb against TNF-a Use: - induction and maintenance of remission in Crohn's and UC Infliximab - UC and CD Adalimumab - UC and CD Certolizumab - CD only Adverse events: - infxn - screen for latent TB and hepatitis B - myelosuppression - increased risk of malignancy - psoriasis - drug induced lupus - dymyelination syndrome
Natalizumab
Anti-integrin
- blocks leukocyte migration from blood vessels to sites of inflammation
Adverse events:
- Progressive multifocal leukoencephalopathy
Vedolizumab
Anti-integrin
- gut specific
- blocks leukocyte migration from blood vessels to sites of inflammation
