GI Flashcards
3 Ways to Tx PUD
- Decrease acid
- Eliminate H. pylori
- Protect mucosa
Antacids (4)
- Aluminum
- Mg
- Calcium
- Sodium bicarbonate
Causes diarrhea
Mg
Causes constipation
Aluminum
Often combined to cancel each other’s effect on GI motility out
- Aluminum
- Magnesium
Considered “candy”
- Antacids, Tums
Drug interactions with antacids common because ______, (4 drugs affected)
They form insoluble complexes with drugs like
- Theophylline
- Ketoconazole
- Quinolone antibiotics
- Tetracycline
Antacids decrease absorption of _______ (3 drugs)
- Digoxin
- Phenytoin
- Propranolol
Antacids increase elimination of _____ (2 drugs)
- Phenobarbital
- Salicylates
What do antacids do to urine?
Alkalinalize
Uses of Antacids (3)
- Relief of heart burn, gastritis
- Temporary fix
- Adjunct to other drugs, because effect is quick
Systemic effects of antacids
- Rare
Antacids affect (2)
- Renal function
- CHF (watch Na)
H2 Antagonists (4)
- Cimetidine
- Ranitidine
- Famotidine
- Nizatidine
H2 Antagonists MOA
- Decrease GI acid formation through H2 receptor blockade
H2 Blockers Tx
- Ulcers
- Most effective at night
- GERD (as adjuncts)
- Pre-anesthesia
- With H1 antagonists for severe allergic rxn
H2 blocker metabolism (3)
- Metabolized by liver, excreted by kidney
- Usually oral
- t 1/2 = 12 hrs
H2 blocker SE
- Few, but worse in elderly
- HA, dizziness, N
- Rash, itch
Cimetidine SE
- Anti-testosterone effect
- May be useful in women (treat hirsutisim)
- Chronic, high doses may cause gynecomastia, loss libido, impotence in men
Cimetidine Drug Interactions (2)
- Inhibits CYP3A
- Warfarin, phenytoin, theophylline, digoxin
Proton Pump Inhibitors (4)
- Omeprazole
- Esomeprazole
- Lansoprazole
- Rabeprazole
Proton Pump Inhibitor MOA (2)
- Activated in gastric parietal cell
- Irreversible block of acid formation
DOC for GERD
PPI
Proton Pump Inhibitor MOA (2)
- Activated in gastric parietal cell to sulfenamide
- Irreversible block of acid formation
- Administered as pro-drugs
PPI SE (6)
- N/D/Colic
- Osteoporosis (decrease Ca absorption)
- Dec Mg absorption (leg cramps)
- HA, dizziness, sleepiness uncommon
- Increase ALT, AST
- Skin rash, bacterial overgrowth possible
May inhibit CYP2C19 –> phenytoin, warfarin, diazepam, clopidogrel possible interactions
Omeprazole
PPI Uses (4)
- Ulcers that haven’t responded to H2 antagonists
- Heal duodenal ulcer or gastric ulcer
- Pts on NSAID
- ZE syndrome
Cytoprotective Agents
- Sucralfate
Cytoprotective MOA
- Polymerizes to provide protective barrier cells in ulcer base
Sucralfate SE
- Constipation (contains aluminum)
- Upset stomach
- Drug interactions
- Prostaglandin E1 analogue
Misoprostol
Misoprostol Tx
- Prevent or reduce NSAID - induced damage
NOT used in pregnancy, can induce abortion
Misoprostol
D2 Antagonist
Metocloropramide
Metocloropramide MOA
- D2 antagonists –> increases ACh release
Metocloropramide SE (3)
- Parkinson’s like symptoms
- Increase prolactin
- Methemoglobinemia in infants (NOT to be used in pregnancy)
Bethanechol MOA
- M agonist
Used in diabetic gastroparesis
Erythromycin
Prokinetic agents
- Metoclopramide
- Bethanechol
- Erythromycin
IBS Tx
- Glycopyrrolate
- Dicyclomine
- TCA (good for pain)
Proton Pump Inhibitors (5)
“Prazole”
- Omeprazole
- Esomeprazole
- Lansoprazole
- Rabeprazole
- Pantoprazole
IBS due to ______ (4)
- Stimulation of 5HT4 receptors on nerve terminal increases ACh release
- Increases peristalsis
- Release of 5 HT from EC stimulates 5HT3 receptors
- Sends pain signal to CNS
Alosetron MOA
- 5HT3 receptor antagonist
Alosetron Tx
- IBS with severe diarrhea in women
Alosetron SE (3)
- Constipation
- GI obstruction, perforation
- MANY contraindications –> risk benefit statement required
Taken off market due to cardiac events
Tegaserod
Tegaserod MOA
5 HT4 partial agonist
5 HT3 Antagonists (4)
“Setron”
- Ondansetron
- Granisetron
- Dolasetron
- Palonosetron
Very effective for N/V induced by chemo, radiation, gastric dz
5 HT3 antagonists (“Setron”)
Prochlorperazine, Promethazinen MOA
Block DA, muscarinic, histamine receptors
Prochlorperazine, Promethazinen Tx (4)
- Post op
- Gastroenteritis
- Chemo
- Motion sickness (not DOC though)
Prochlorperazine, Promethazinen SE
- Highly sedating
Used for chemo induced N/V, stimulates appetite
- Dronabinol, Medical marijuana, Nabilone
Laxative MOA (4)
- Increase GI motility
- Prevent reabsorption of water/electrolytes
- Enhance secretion of water/electrolytes
- Dissolve or lubricate feces
Bulk forming agents
- Fiber (dietary, methylcellulose, psyllium, polycarbophil)
- High fiber diet best
Fiber SE
- Bloating and flatulence common
Osmotic laxatives (3)
- Mg Hydroxide (stimulate GI tract, increase peristalsis)
- Na Salts (oral, enema)
- Sorbitol, Mannitol, Sucralose (sweeteners)
Polyethylene glycol MOA
- Insoluble, holds water in intestine
Polyethylene glycol Tx
- Prep for colonoscopy
OTC for ocassional constipation
Miralax used for up to 7 days
Lactulose Tx
- Used in cirrhosis and liver dz to decrease blood ammonia levels
Lactulose MOA (2)
- Conversion to lactic acid, decrease pH in gut lumen
- Traps ammonium in gut lumen
Lactulose SE (2)
- Flatulence
- Diarrhea
Mucosal Agents (3)
- Bisacodyl
- Senna
- Castor oil
Mucosal Agent MOA
- Stimulate peristalsis
- Enhance secretion/inhibit absorption H2O
Intense Mucosal agent that is not recommended
Castor oil
Mucosal Agent Tx (2)
- Surgery
- Diagnostics
Mucosal Agent requires _____
Bile
Mucosal Agents CI
- Pregnancy (stimulates uterus)
Lubricants/Softeners MOA
- Increase bulk
- Soften and lubricate stool
Lubricants/Softeners (3)
- Mineral Oil
- Docusate
- Glycerin
- – Not very effective
Mineral Oil MOA
Fat soluble vitamins, inhalation orally (aspiration PNA), leaking (need to wear depends)
Docusate MOA
Emulsifies, softens, may incraese water
Glycerin MOA
Lubricate
Lubiprostone MOA
- Prostaglandin E1 analogue
- Activates CIC-2 Cl channels in luminal cells to increase fluid secretion
Lubiprostone Features (6)
- Softer stool, better motility
- Fewer symptoms of constipation
- No effect on electrolytes
- No lax dependence
- N/D, HA
- Not absorbed systemically
Use of Laxatives (7)
- Reduce straining
- Maintain soft stools
- Empty bowel for dx or surgical procedures
- Decrease bowel tone
- Geriatrics, preg
- Get rid of pathogens/toxins
- Constipation
Contraindications of Laxatives
- N/V
- Abd cramps
- Undx abd pain
- Appendicitis
- Intestinal obstruction
Over use of laxatives can lead to (4)
- Dependence
- Fluid/electrolyte imbalance
- Spastic colitis
- Ulcerative colitis
Diarrhea drugs MOA (3)
- Absorb excess water (Fiber, Al salts)
- Inhibit secretion
- Decrease motility (opioids, anticholinergics)
Absorbents MOA (3)
- Absorb water, form gel-like mass
- Increase bulk
- Dietary (bananas, applesauce)
- Not very effective
Opioids in Diarrhea
- Loperamide (Imodium)
- Diphenoxylate/ atropine (Lomotil)
Loperamide (Imodium) Features (2)
- Does NOT enter CNS (low abuse)
- May cause abd pain/constipation
Diphenoxylate/ atropine (Lomotil)
- With atropine, decreases abuse, increase effectiveness
- Anticholinergic SE
Opioid CI
- Infections (dec expulsion of pathogens)
- Ulcerative colitis (toxic megacolon)
- Recovering drug addicts (some abuse potential)
Bismuth subsalicylate MOA
- Absorb water
- Absorb pathogens
Bismuth subsalicylate Tx
- Traveller’s diarrhea
Black tongue, mouth and stool
Bismuth subsalicylate
Bismuth subsalicylate CI
- Pts allergic to aspirin
- Childrens (reyes)
- Caution in asthmatics
Simethicone MOA (FYI)
- Coats gas, dissipates
- Decreases bloating flatulence
Sulfsalazine (FYI)
- Antiinflamm
- 5 aminosalicylic acid plus sulfapyridine
- Bacteria in GI tract activate it
- Used in Inflamm bowel dz
- Allergic rxn possible
- Avoid in children (reyes)
