Koh GI Flashcards
GERD
Heartburn, food/acid in esophagus
From faulty sphincter, hiatal hernia, obesity, preg
Gastric Ulcer
Lesser curvature of stomach
Pain after eating
some N+V
Older people-10%
Duodenal Ulcer
Upper duodenum
pain 2-4 hrs after eating (food helps)
Rarely N/V
Younger pop-90%
Stress Ulcers
More acid, less mucus and blood Q
mucosal injury in stomach
very ill pts, but heals fast
EtOH or steroid induced
Defensive factors
Mucus
Bicarb
Blood Flow- maintains mucosal integrity
Prostaglandins (PGE1+2) inhibit acid
Aggressive Factors
Gastric and Bile Acids Pepsin H. pylori (75% of cases) NSAIDS Smoking
Cells of Acid Secretion
Parietal- gastrin, H2, M3
Enterochromaffin like- gastrin + M3
->cause histamine relase
Antacid “interactions”
Increases gastric emptying
Binds with Fe and tetracyclines
Urinary alkalization
Caution in renal failure
Sodium Bicarbonate
Systemic, rapid, short DOA
Best agent, but in combos
Caution in Na restricted pts
Calcium Carbonate
Partially systemic, rapid, longer DOA
still subject to rebound, CO2, and Milk-Alkali
Magnesium Products
Non-Systemic, fairly rapid
Mg not absorbed but caution in renal failure
Diarrhea main SE
Aluminum salts (Rolaids)
Non-Systemic, not absorbed
Slow acting, sustained
binds phosphate
Constipation main SE
Simethicone (Mylanta)
Defoaming agent that increases surface tension of gas bubble to speed passage in gut
H2 blockers (general)
decreases both basal and stimulated acid
»decreases pepsin levels
no effect on GI emptying or tone
Safe, minor SE, DrOCh for IV
PPIs
most prescribed class irreversible antagonist of H/K >>covalent bond short half life, no dose reduction DOC for GERD and PUD
Ulcer healing time
gastric = 6-8wks duodenal = 4wks
“Triple Therapy”
PPI (antimicrobial) + 2 antibiotics x2wks
Sucralfate
sulfated sucrose, forms paste barrier
no effect on pH
decrease absorption of some drugs
misoprostol (Cytotec)
mimics PGE1
inhibits acid, increases bicarb and mucus
TID-QID, CI in preggers
FDA approved for ulcers
Pepto Bismol
bismuth not absorbed, salicylate is
antimicrobial, coats ulcers, reduces poop freq
never give if under 12
Bulk-forming laxatives
Absorb water to increase bulk results in 1-3 days methylcellulose polycarbophil psyllium
Emollients (stool softeners)
allow lipids and water to penetrate stool
1-3 d PO, 6-12hrs rectally
docusate products
Lubricants
coats stool»stops H2O reabsorption
results in 8hrs
mineral oil and glycerine supp.
take 2hr before or after food
Osmotics (saline) properties
draws fluid into stool
for pre-op
can lead to dehydration
poop in 1-3hrs w high dose, 2-8 low dose
Osmotics products
Sugars/Salts: MgOH, sorbitol, lactulose, Mg citrate or phosphate, Na phosphate.
Polyethylene Glycol: large volumes given, “inert”
Stimulant Products (irritants, carthartics)
anthraquinone (senna, cascara) 2hr rect
diphenylmethane (bisacodyl) 30min rect, used w PEG
castor oil
Chloride Channel Activator
lubiprostone (Amitiza)
PG derivative
For IBS-C in women
Opioid Antagonists
methylnaltrexone (Relistor)
alvimopan (Entereg) CV toxicity!!
5-HT4 Agonists
tegaserod (Zelnorm) for IBS-C
cisapride (Propulsid)
CV SE!!
Acute Diarrhea Tx
4-6H, no food 6-12H, liquids 12H, simple foods Avoid dairy drug treatment
diphenoxylate (+atropine=Lomotil)
congener of meperidine
high doses»morphine like
atropine discourages abuse
loperamide
no abuse potential
doesn’t cross BBB
longer DOA than diphenoxylate
Acute Watery T. Diarrhea
E. coli, shigella, salmonella
bind to mucosa, produce cAMP/GMP
»water and elec. in stool
Pepto+doxycyline
Dysentery T. Diarrhea
shigella, entamoeba
blood and/or mucus in poop
fecal-to-oral
treat w antibiotics
Giardiasis T. Diarrhea
giardia lamblia
gastric pH promotes cyst survival
2-6wks, metronidazole as tx
Vomiting receptors
M3, H1, NK1, 5-HT3
Chemoreceptor trigger zone (CTZ)
aka “area postrema”
D2 dopamine and opioid receptors
Vestibular System
motion sickness
M1 and H1
Vagal and spinal nerves
GI mucosal cells release serotonin,
5-HT3 receptors, prov-vomiting signals
5-HT3 antagonists
features
DOC for prevention during chemo or postoperative emesis
CYP metab and renal excretion
Neurokinin receptor antagonists
aprepitant (capsule)
fosaprepitant (inj)
combo with 5HT3 blockers and corticosteroids
CYP3A4»interactions (chemo+warfarin)
Phenothiazines
anti-psychotics
prochlorperazine (Compazine)
promethazine
Butyrophenones
anti-psychotics
droperidol
AE: prolongation of QT interval
Benzamides
And MOA
metaclopramide and trimethobenzamide (Tigan)
block DA receptors
Cannabinoids
MOA unknown for anti-emetic
dronabinol, nabilone
pt supervision recommended
Morning Sickness
unknown cause
conservative treatment!
antihistamines or metaclopramide if severe
Hyperemesis gravidarum
2-5% of pregnancies
uncontrolled vomiting
antihistamines then phenothiazines
Irritable Bowel Syndrome
idiopathic, relapsing,
pain, bloating, cramps, dia&const
discomfort 3x/month x3months
treat pain w low dose TCAs
dicyclomine (Bentyl)
For IBS (antispasmodic) muscarinic antagonists SE: const.
hyoscyamine (Levsin)
For IBS (antispasmodic) muscarinic antagonist SE: const.
alosetron (Lotronex)
5HT3 antagonist
decrease discomfort, increase stool firmness, decrease fecal urgency
approved for IBS-D in WOMEN
lubiprostone (Amitiza)
Chloride channel activator
prostaglandin analog as laxative
for IBS-C in WOMEN
Preg category C
tegaserod (Zelnorm)
5HT4 Agonist
promotility
for IBS-C in women
use only in emergency w healthy CV
Ulcerative Colitits
inflamm of sub/mucosa of colon and rectum
immune cells respond
possible rectal bleeding
Crohn’s Disease
inflamm of any layers in any GI section
commonly in terminal ileum
surgery often results
Hepatic Lobule
From portal vein and hepatic artery to the central vein
Portal Lobule
Drains bile from central vein (hepatocyte) to bile duct in portal triad
Acinus
Zone I: mitochondria rich, have portal vein and hepatic artery
Zone III: Many CYPs, central vein
Bile componenets
Glutathione Phospholipids Cholesterol Bilirubin Bile salts
Canalicular Choestasis
decrease in V of bile or component of it
leads to high serum levels of bile salts/bilirubin
caused by metals, hormones, drugs
inhibit active transport
Sinusoidal Damage
by Dilation: efflux impeded
Blockade: RBCs caught in fenestrae
Destruction of ECs
Toxins: Anabolic steroids, cyclophosphamide
Metoclopramide
Reglan
Dopamine D2 antagonist
Increase Ach, prokinetic
No effect on SI or colon
IBS drugs for women only
Tegaserod, IBS-C
Lubiprostone, IBS-C
Alosetron, IBS-D
