Drugs are bad, m'kay.... Flashcards
proton pump inhibitors (PPI)
oral once a day
IV: GI ulcer bleeding (not FDA approved)
SUPERIOR to H2 blockers
-prazole
irreversible inhibition of H/K ATPase
acid labile: ENTERIC COATING: erratic absorption
taken up by parietal cells and protonated to trap there: short T1/2 but effect lasts longer
metabolized by CYP2C19, 3A4
most effective for basal and food stimulated acid
take BEFORE FOOD
NO tolerance develops
Tx: hyperacidity: GERD, PUD, ulcer bleeding (not approved)
AE: slight increase in enteric infections, possible rebound acid secretion on withdrawal, possible increase risk of fractures
may be CI in Vit. B def. due to reduced absorption
H2 blocker
-tidine
competitive antagonists
take before bed: most effective for basal/overnight acid (doesn’t help for mealtime acid)
MODEST inhibition of gastric secretion from parietal cells
TOLERANCE within days
Tx: hyperacidity: GERD (only in mild cases), PUD (no longer recommended since PPI is superior and H. pylori assoc.); basically just for mild intermittent heartburn
ranitidine
H2 antagonist
cimetidine
H2 blocker
CYP inhibitor
drug interactions: phenytoin, warfarin, theophylline
nizatidine
H2 blocker
famotidine
H2 blocker
esomeprazole
PPI
drug interaction: possibly clopidogrel
lansoprazole
PPI
omeprazole
PPI
nasogastric or orogastric tube: in formulation with NaHCO3 for accelerated absorption rather than enteric coating: only PPI approved for upper GI bleed
also oral enteric coat form
CYP inhibitor
drug interactions: phenytoin, warfarin, diazepam, possibly clopidogrel
rabeprazole
PPI
mesalamine
5-aminosalicylic acid
Tx: ulcerative colitis (orally and rectally)
continue rectal until bleeding stops
stay on oral
bulk-forming laxatives
hydrophilic: form mass when mixed with water
in lumen: absorb and retain water and increase bulk in GI: stimulate stretch receptors to peristalsis
Tx: constipation
carboxymethylcellulose (Citrucel)
bulk-forming laxative: colloid mass
digestible
AE: impedes concurrent drug absorption
OFF LABEL: IBS-C
metamucil (Psyllium)
bulk-forming laxative: gelatinous mass absorb water Tx: constipation, diarrhea AE: flatulence, esophageal obstruction, choking, allergic rxn may inhibit warfarin absorption OFF LABEL: IBS-C
polycarbophils (Mitrolan)
bulk-forming laxative: polyacrylic resins
absorb 60-100x their weight in water
Tx: IBS-C
CI: Ca2+ release may chelate tetracyclines
osmotic (saline) laxative
Mg cations or other non absorbable molecules (Phosphate)
osmotic: retain water in lumen of GI tract: stimulate stretch receptors in increase cholinergic activity in ENS
Ex: Mg sulfate, hydroxide, citrate (citrate is cathartic); Pi containing given as enema or tablet
CKK release: increase intestinal motility and secretion
Tx: constipation
lactulose
osmotic laxative
non-absrobable disaccharide
fecal acidifier: metabolized to organic acids: lactic, acetic, formic: traps ammonia in ammonium form (slows diffusion into blood)
decreases glutamine and NH3 absorption
Tx: constipation; portal-systemic encephalopathy (adjunct to protein restriction and supportive Tx)
polyethylene glycol (PEG; Golytely)
osmotic laxative
dissolve in 4 L water
Use: bowel prep for colonoscopy, constipation, IBS-C
CI: bowel obstruction (nausea, vomiting, abdominal pain or distention) or perforation
docusate sodium (Colace)
anionic surfactant laxative
stool softener: reduce strain of defecation
NO direct stimulatory effect on peristalsis
Tx: constipation
CI: abdominal pain, vomiting
AE: irritate intestinal mucosa, increase absorption of other drugs
SHORT TERM use
chloride channel activators
laxative
increase volume and hydration of stool: stretch recpetors cause peristalsis
Tx: constipation, IBS-C
AE: abdominal distention and pain, diarrhea, flatulence
linaclotide
chloride channel activator: increase intestinal secretion and motility
CFTR
agonist of GC (guanylate cyclase) C2; cGMP; PKG: INDIRECT activation of chloride channel
Tx: constipation (idiopathic and IBS-C)
CI: in children less than 6 yrs
lubiprostone
PGE1: chloride channel activator: increase intestinal secretion and motility DIRECT: CLC channel PKA INDEPENDENT Tx: constipation (IBS-C) AE: nausea
loperamide
opiate agonist
binds calmodulin
chloride secretion blocker and enteric neural blocker: direct action on sm. muscle to slow motility
Tx: diarrhea
AE: hyperglycemia, GI pain (N/V); somnolence
OFF LABEL: IBS-D
opiate antagonist
Tx: opiate induced constipation
methylnaltrexone
opiate antagonist
AE: abdominal pain, flatulence, nausea, GI perforation (increased risk with compromised structural integrity)
naltrexone
opiate antagonist
AE: reverses analgesia (cautious in pain patients)
opiate agonist
What do you add and why?
- decrease secretions and motility
- increase muscle tone of sphincters
- anti-spasmodics: decrease cramps
Tx: diarrhea
add ATROPINE: prevent opioid abuse
paregoric
opiate agonist
add atropine
Tx: diarrhea
diphenoxylate
opiate agonist
add atropine
Tx: diarrhea
stimulant laxatives
most potent laxatives
act on large bowel
1. increase permeability of intestinal mucosa: increase back diffusion of water and electrolytes into lumen
2. increase contractility by stimulating myenteric plexus
3. stimulate PGs: increase secretions
Tx: constipation
senna (anthraquinone)
stimulant laxative
natural derivative: more gentle
Use: bowel prep for colonoscopy
AE: finger clubbing (with abuse), electrolyte imbalance and nephritis (excessive use); dark pigmentation of colonic mucosa, pink urine
bisacodyl (diphenylmethane; dulcolax)
stimulant (ENS) laxative
prodrug: converted to desacetyl by bacteria
enteric coat
local axon and segmental reflexes stimulated: produces widespread peristalsis
effective in SPINAL CORD INJURY
AE: excessive fluid and electrolyte loss leading to colonic inflammatory response
castor oil
surfactant laxative
rapid
irritates mucosa: cathartic effect
AE: colic, dehydration, electrolyte imbalance, uterine contraction
mineral oil
stool softener
mixture of hydrocarbons
Tx: constipation
AE: anal irritation, fecal incontinence
poloxamer 188
non-ionic surfactant stool softener Tx: constipation AE: diarrhea CI: GI pain or N/V (promotes diarrhea)
anticholinergics
regular vs. quaternary
reduce vagal stimulation; anti-spasmodic
Tx: diarrhea
often combined with: benzodiazepine sedative
REGULAR
use: IBS diarrhea
AE: indiscriminate anti-muscarinc activity
QUATERNARY
do NOT cross BBB: no CNS activity
use: antispasmodic (alleviate cramps), antidiarrheal
AE: xerostomia, vision change, bradycardia followed by tachycardia, impotence, bladder, flushing, annhidrosis
atropine
anticholinergic
Tx: IBS
use: combine with opioids to prevent abuse
dicyclomine
anticholinergic
quaternary amine
Tx: diarrhea, IBS
more suited to alleviate cramps
glycopyrrolate
anticholinergic
OFF LABEL: IBS
propantheline
anticholinergic
quaternary amine
Tx: diarrhea
more suited for urinary retention
bismuth subsalicylate
antidiarrheal, antiinflammatory
- stimulates fluid/electrolyte absorption across the intestinal wall (antisecretory action)
- inhibits PG synthesis (reduces intestinal inflammation and hyper motility)
- binds toxins produced by E. coli
use: H. pylori quadruple therapy, prevent traveler’s diarrhea
methysergide
serotonin inhibitor
Tx: carcinoid tumor
inhibits serotonin induced diarrhea
serotonin antagonist
-setron: 5HT3 blockers
Tx: diarrhea or emesis
alosetron
serotonin (5HT3) antagonist
little affinity for dompaminergic or other serotonin receptors
Tx: IBS-diarrhea
AE: COLITIS and SEVERE CONSTIPATION (BBW), arrhythmia, obstruction, perforation, toxic megacolon
physician must enroll in PRESCRIBING PROGRAM
use in combo with corticosteroids with/out benzodiazepines
amoxicillin
penicillin: binds PBP
use: H. pylori triple therapy
resistance does not develop
AE: diarrhea
clarithromycin
macrolide use: H. pylori triple therapy low order of toxicity RESISTANCE: do NOT use more than once in H. pylori AE: taste disturbance, diarrhea
metronidazole
oral
IV: complicated C. diff disease
use: C. difficile (mild-mod), H. pylori triple therapy if allergic to penicillin
RESISTANCE can develop: change dose if use again in H. pylori
CI: PREGNANCY, BREAST FEEDING
AE: peripheral neuropathy, disulfarim effects, diarrhea
tetracycline
Tx: H. pylori quadruple therapy
resistance does not develop
AE: diarrhea, teratogen
fidaxomicin
macrolide: inhibits bacterial RNA polymerases
remains in GI: little systemization
Tx: C. difficile (not recommended yet)
SUPERIOR response (and less recurrence) in high risk C. diff to vanc
AE: GI (N/V; abdominal pain, bleed)
EXPENSIVE
stool transplant
colonoscopy (seems to be best way): blended with saline and filtered through gauze
gastroscopy
NG tube
microbiome replacement
recipient: STOP antibiotics 203 days before; colonoscopy prep to reduce stool; loperamide after transplant
donor: no recent antibiotics; screen for pathogens; test for Hep. A/B/C, syphilis, HIV; milk of magnesia as softener
Tx: C. difficile
vacomycin
oral
IV: complicated C. diff disease
rectal: ileus, distention, anatomic/surgical abnormalities pts (when oral can’t reach colon)
extended Tx with oral: 2nd recurrence
cell wall synthesis inhibitor: binds D-ala, D-ala
Tx: C. diff (severe, pregnant/lactating women)
AE: hypokalemia, abdominal pain, diarrhea, N/V
aluminum hydroxide
antacids
AE: constipation