GI Flashcards
AE of antacids
decreases oral absorption of tetracyclines with milk (Ca), antacids (Ca/Mg) or iron containing meds (via chleation)
increaes oral absorption of weak bases (quinidine)
decreases oral absorption of weak acids (warfarin)
enhancement of gastric acid secretion
1) histamine
2) acetylcholine
3) gastrin
MgOH AE
produces Mg salt - poor absorption –> diarrhea
AlOH AE
reacts with HCL –> AlCl = insoluble and causes constipation and hypophosphatemia
CaCO3 AE
hypercalcemia
nephrolithiasis
constipation –> fecal compaction
Reversible H2 blockers
1) cimetidine
2) ranitidine
3) famotidine
3) nizatidine
cimetidine = shortest acting, and least potent
H2 blocker use in ICU pt
prophylaxis for acute stress ulcers
H2 AE
nausea, HA, dizzy
cimetidine: anti-androgenic effects - newer H2’s don’t do this and don’t inhibit CYP450
Cimetidine AE
1) gynecomastia
2) inc prolactin
3) dec libido
4) confusion in elderly
crosses BBB and placenta
cimetidine+ranitidine = dec renal excretion of creatinine
Cimetidine contraindicated with
CYP 450 inhib - AE with warfarin, procainamide, phenytoin, benzo, theophylline, imipramine, quinidine
Omeprazole contraindicated with
warfarin, clopidogrel, phenytoin, diazepam, cyclosporine
- omeprazole inhibits their metabolism
PPI AE
inc in respiratory and GI infection
dec Mg serum levels – hip fractures
prolonged use with H2 blockers = dec avail of B12, digoxin, and ketoconzaole
1st lines for h pylori
macrolides: clarithromycin
B-lactam: amoxicillin
antiprotozoals: metronidazole
broad spec: tetracycline
clarithromycin MOA
bacteriostatic
binds 23S rRNA of 50s = prevents translocation
clarithromycin uses
h pylori atypical PNA CAPNA pertussis corneybacteria
clarithromycin AE
binds motilin receptors - GI upset: n/v
prolonged QT = arrhythmias
hepatitis
eosinophilia
affect oral anticoagulants via CYP450 inhibition
**resistance: methylation of 23s binding site - no binding of drug
Amoxicillin MOA
bactericidal - bind transpeptidase = prevent cross linking of PTGN - autolytic enzymes activated
amoxicilin use
h pylori
G+ and some G(-)’s
amoxicilin AE
rash, hypersensitivity, pseuomembranous colitis
resisitance = b-lactamase cleaves b-lactam ring
metronidazole MOA
bactericidal
inhib. electron transport system - toxic metabolites that damage DNA
metronidazole use
h pylori
c diff
bacteroides
antiprotozoal
metronidazole AE
flushing
tachycardia
low BP with alcohol (like disulfiram)
metallic taste
tetracycline MOA
binds 30s and prevents aminoacyl-tRNA attachment
tetracycline AE
GI upset, discolored teeth, inhibited bone growth in kids, photosensitivity
resistance: reduced uptake/inc efflux out of bacterial cells by plasmid encoded transp pumps
metoclopramide MOA
5HT3 and D2 blocker = anti-emetic
5HT4 agonist - muscarinic activity = prokinetic
metoclopramide use
diabetic, post op gastroparesis, relief GERD sxs
prokinetics (4)
1) metoclopramide
2) 5HT4 agonists
3) cholinomimetics
4) macrolides
metoclopramide AE
anti-dopaminergic: sedation, diarrhea, parkinsonian
possib inc prolactin = infertility
cisapride MOA
5HT4
cisapride use
gastroparesis, GERD, constipation via Ach stimulation
- not a first line b/c of AE
cisapride AE
arrhythmias
Cholinomimetics types
1) neostimgine - colonic pseudoobstruction
2) bethanechol - resistance to cholesterase: long duration for post op bladder/bowel atony
erythromycin MOA
acts on motilin receptors
erythromycin use
gastric emptying before endoscopic procedures
- if used for extended period, develops tolerance
anti-emetic agents
1) 5HT3 inhib
2) H1 antihistamine and anti-muscarinic
3) NK1 blocker
4) corticosteroids
5) D2 blocker
6) metoclopramide
7) cannabinoids
Ondansetron MOA
5HT3 blocker
Ondansetron AE
QT prolongation/arrhtyhmias
H1 antihistamines MOA
block peripheral and CNS H1
block alpha and muscarinic
HI antihistamine uses
hay fever, angioedema, motion sickness
NK1 drugs
1) arepitant = PO
2) fosaprepitant = IV
NK1 use
decreasing early and delayed emesis in cancer chemo
glucocorticoid agonists AE
adrenal suppression growth inhibition muscle wasting osteoporosis salt retention glucose intolerance behavior changes
glucocorticoid agonists (2)
1) dexamethasone
2) methylprednisolone
first line chemo induced nausa/vomiting
dexamethasone Or methylprednisolone + ondansetron or combination of both
D2 blockers (3)
1) phenothiazines: D2 and M blockers
2) promethazine: anti-dop and anticholinergic
3) droperidol: anti-dopaminergic, antiemetic, antipsychotic, neuroleptic analgesic
Benzodiazepines (3)
lorazepam
alprazolam
diazepam
Dronabinol
acts on CB1 as agonist - cannabinoid
anti-diarrheals
1) opoid agonist (loperamide, diphenoxylate)
2) somatostatin analog (octreotide)
3) bismuth
Methotrexate - be sure to give (high/low) doses
LOW doses when not for cancer treatment
IBS tx (4)
1) anticholinergics: hyoscyamine, dicyclomine, glycopyrrolate, methscopalamine
2) 5HT3 blockers: alosetron
3) opioid agonists: loperamide
4) chloride channel activators: lubiprostone
PPI MOA
PPIs once in parietal cell - converted to active form, react with cysteine residue of H/K ATPase = stable covalent bond forms = IRREVERSIBLE inactivation of enzyme
Mucosal protective agents (3)
sucralfate
bismuth subsalicylate
misoprostol
sucralfate MOA
selectively binds to necrotic tissue = barrier to acid
stimulates PG synthesis
mucosal protective
sucralfate contraindications
ineffective if given with H2 blockers or PPI = requires acidic environment for activation
bismuth subsalicylate MOA
selectively binds ulcer and forms coating = protect from acid and pepsin
misoprostol MOA
prevent gastric ulcers induced by NSAIDs: activate EP receptors = inc HCO3 and mucus
PGE1
also ineffective with PPI or H2
misoprostol AE
diarrhea
uterine cramping
abortifacient
exacerbate IBD
loperamide
antidiarrheal opiate derivate
diphenoxylate
antidiarrheal opiate derivative
Opiate derivates for antidiarrheal MOA
act at GI mu opioid receptors: inhib Ach and dec peristalsis
Diphenoxylate AE
high doses can cause CNS effects
formulated with atropine to reduce abuse
octreotide
somatostatin analog - anti-diarrheal
somatostain analog use
diarrhea
carcinoid syndrome associated flushing
VIP secreting tumors
control bleeding from esophageal varices and acromegaly
ocreotide AE
GI disturbance
gall stones
bradycardia
cardiac conduction anomalies
Laxative mechanisms
1) stimulants
2) bulk forming agents
3) osmotic agents
4) stool softeners
5) chloride channel activator
6) opioid receptor antagonist
senna
laxative - stimulant
bisacodyl
laxative - stimulant
methylcellulose
laxative - bulk forming agent
psyllium
laxative - bulk forming agent
bran
laxative - bulk forming agent
magnesium oxide
laxative - osmotic agent
magnesium hydroxide
laxative - osmotic agent
lactulose
laxative - osmotic agent
polyethylene glycol
laxative - osmotic agent
osmotic agents as laxatives AE
Mg may be absorbed and cause toxicity in renal impairment
lactulose USE
hepatic encephalopathy - draws out NH3 from body to prevent hyperammonia
glycerin
stool softening laxative
docusate
stool softening laxative
lubiprostone
chloride channel activator laxative
tx for IBS associated constipation
lubipristone
tx for opioid induced constipation
senna + docusate OR opioid receptor antagonists (alvimopan/methylnaltrexone)
alvimopan
opioid receptor antagonist laxative
methylnaltrexone
opioid receptor antagonist laxative
Drugs used in IBD
1) aminosalicylates
2) glucocorticoids
3) immunosuppressants
4) anti-TNFalpha
5) anti-integrins
sulfasalazine
aminosalicylate used for IBD
sulfasalazine MOA
inhibits eicosanoid inflam mediators
sulfasalazine contraindications/AE
avoid in pt with sulfa allergy
HS. reversible oligospermia. BM suppression
mesalamine
aminosalicylate used for crohns and UC
mesalamine target
distal ileum and colon
Balsalazide
aminosalicylate used for UC
balsalazide target
large intestine - targets site of UC
glucocorticoids used for IBD
1) hydrocortisone
2) prednisone
3) prednisolone
4) budesonide
budesonide target
glucocorticoid used for IBD = distal ileum and colon
immunosuppressant used to treat IBD
MTX
MTX AE
nausea mucosal ulcers hematotoxicity hepatotoxicity teratogen
6 mercaptopurine
immunosuppressant tx UC and CD
azathioprine
immunosuppressant tx UC and CD
6-MP AE
myelosuppression, immunosuppresion, hepatotoxicity
infliximab
anti-TNF alpha drug for UC and CD
adalimumab
anti-TNF alpha drug for UC and CD
anti-TNF alpha AE
reactivation of latent TB
natalizumab
anti-integrin: blocks leukocyte integrins and can cause PML
IBS tx (4)
1) anticholinergic
2) 5HT3 antagonists
3) opioid agonist
4) chloride channel activators
anticholinergics for IBS
1) hyoscyamine
2) dicyclomine
3) glycopyrrolate
4) methscopalamine
anticholinergic IBS drugs AE
delirium, hallucinations, coma, tachy, HTN, hyperthermia
Alosteron
5 HT3 antagonist tx IBS
alosteron AE
ischemic colitis
loperamide
opioid agonist in IBS - diarrhea!
lubiprostone
chloride channel activator in IBS - constipation
ursodiol
bile acid therapy for gallstones