pharm Flashcards
antimuscarinic agents
MOA: Competitively inhibits autonomic, postganglionic cholinergic recptors= Decreased GI motility and spasm Indication: Abd pain/spasm hyoscyamine dicyclomine clindinium chlordiazepoxide
Opioid Agonists
DIARRHEA: interfere with peristalsis
Loperamide (first line therapy for microscopic colitis)
Diphenoxylate (atropine added)
Eluxadoline (IBS-D) **hepatic and pancreatic toxicity, risk of pancreatitis in pt’s without gallbladder, CNS related euphoria/dizzy/cognition
Eluxadoline
opioid agonist used for IBS-D
SE: GI sx, hepatic and pancreatic toxicity, pancreatitis increased risk in pt w/out gallbladder, CNS
Contraindicated: biliary tract obstruction, ETOH, h/o pancreatitis, sever hepatic impairment.
5-HT3 receptor antagonist (for diarrhea)
Alosetron
Selectively blocks GI based 5HT3 receptors
antagonism in GI modulates regulation of visceral pain, colonic transit, and GI secretions
Tx: Chronic severe IBS-D (women)
Contraindications:
GI obstruction, perforation, stricture, adhesion, toxic megacolon
diverticulitis, CD, UC
impaired intestinal circulation, thrombophlebitis, hypercoagulable states
severe constipation (D/c alosetron immediately)
SE: constipation, DYSPEPSIA, GERD, nv
ISCHEMIC COLITIS
Cl- channel inhibitor
DIARRHEA
Crofelemer (derived from tree sap)
inhibits Cl- secretion by blocking cAMP stimulated CFTER and Ca2+ activation of Cl- channels
leads to dec fluid secretion
**Indicated for noninfectious diarrhea in HIV/AIDS (on antiretroviral therapy)
SE: Abd distension, increased liver enzymes and bilirubin, infections
Peripheral opioid antagonist
CONSTIPATION
mu opioid receptor antagonists
Methylnaltrexone: tx: OPIOID INDUCED CONSTIPATION
Alvimopan: prevention of post-op ileus only** only for accelerating time to GI recovery following bowel resection surgery w/ primary anatomoses
-carries risk of MI
Alvimopan
mu opioid receptor antagonist
prevention of post-op ileus only** only for accelerating time to GI recovery following bowel resection surgery w/ primary anatomoses
-carries risk of MI
Methylnaltrexone
Mu opioid receptor antagonist
tx: OPIOID INDUCED CONSTIPATION
Linaclotide
selective guanylate cyclase-c (GC-C) agonist
-binds GC-C on lumen of intestinal epithelia and increased IC/EC [cGMP] which + secretion of Cl-/HCO3- into lumen via activation of CFTER
results in inc intestinal fluid and peristalsis
tx: IBS-C and chronic idiopathic CONSTIPATION
SE: diarrhea, GERD, dyspepsia, n/v
Lubiprostone
selective Cl- channel activator
a PGE-1 derivative-> inc intestinal fluid by + GI specific Cl- channels (ClC2)
indicated for IBS-C, chronic idiopathic CONSTIPATION, and opioid induced constipation
SE: n/dyspepsia, dizzy
stimulants (irritants)
\+ peristalsis, irritant to enterocytes bisacodyl castor oil (recinoleic acid) glycerin (precolonoscopy, irritant, osmotic and lubricant) senna (urine discoloration) Na+ Picosulfate
**Contraindicated in GI obstruction/ILEUS/Impaction
Osmotics
Lactulose (also used for sever liver dz(hyperammonemia) change in pH traps ammonia in GI)
Mag Citrate
Polyethylene Glycol (PEG) Miralax (large doses used for bowel prep prior to scope, procedures, surgery)
Sorbitol (glycerin)
works in 1-2 days sooner if larger dose
Salines
Mag Hydroxide
Na+ phosphate
Magnesium and phosphate poorly absorbed, osmotically retain water in GI lumen
**interact with DIURETICS, use caution in renal dz, CHF, HTN
Bulk forming
dietary fiber Psyllium Methylcellulose carboxymethylcellulose Ca polycarbophil
work to inc bulk volume and water content thereby inc GI motility
Drink lots of water to prevent bloating/obstruction
lots of drug interactions (psyllium and celluloses)
Stool Softeners (surfactant, emollient)
Docusate
Mineral oil
soften feces, inc fluid secretion and inhibit water reabsorption
Metronidazole (5-nitroimidazoles) MOA
a prodrug activated by susceptible organisms (anaerobic pathogens) - redox potential - electron donated to metronidazole - highly reactive nitro radical anion formed -kills organisms by radical mediated DNA damage.
then can be catalyticaly recycled
resistance: inc intracellular O2
Metronidazole spectrum
active against anaerobes
flagellated protozoa (T. vaginalis, G. lamblia)
E. histolytica
anaerobic cocci and anaerobic G (-) bacilli
Helicobacter and Campylobacter spp.
G+ bacilli (Clostridium sp) (C. diff)
Metronidazole adverse effects
metallic taste in mouth
dry mouth, nausea, HA
Disulfiram-like effect (anti-EtOH effect, induces emesis)
Tinidazole similar but somewhat better tolerated
C. diff infection
cessation of inciting abx (Ampicillin, Clindamycin, Fluoroquinolones)
supportive
Vancomycin (preferred tx for severe CDI) Oral only
Metronidazole (mild CDI, sometimes if cant tolerate PO
Fidoxamicin (tx for recurrent CDI, spares many anaerobic colonic flora)
H. pylori tx
Bismuth subsalicylate
Metronidazole
Tetracycline
Omeprazole
Entamoeba histolytica
trophozoites invade intestine mucosa- portal blood circulation - LIVER ABSCESS - pulmonary or brain abscess (often death)
**Pathogenic if RBCs in cytoplasm
India, Mexico, Colombia
causes: Dysentery and Liver abscesses (occasionally toxic megacolon or pneumatosis coli)
* **MCC dysentery in the world
Entamoeba histolytica tx
Eliminate invading trophozoites: Metronidazole AND Tinidazole
Luminal amebicide: Paromomycin or iodoquinol
asx carrier tx with luminal amebicide
Giardia lamblia
Trophozoit -> cyst “pear/kite shaped”4 flagella, 2 nuclei
interferes with fat absorption
asx or WATERY (malodorous diarrhea)persistent diarrhea
dx: ova parasites, stool ag detection, fecal leuk -
acquired: lakes/streams/camping, zoonosis, daycare, Russia, IgA deficient more susceptible
Entamoeba histolytica dx
flask shaped ulcer on histology
ova and Parasite in stool
STOOL AG
fecal leuk +
Giardia lamblia tx
supportive tx
Tinidazole
Nitazoxanide- inihibition of pyruvate-ferredoxin oxidoreductase enzyme (essential for anaerobes) a prodrug
Cryptosporidium parvum
Oocyst with 4 motil sporozoites
person to person
self-limited diarrhea in immunocompetent
**life-threatening intractable in immunosuppressed
WATERY diarrhea (large volumes)
risk factors: food/water, SWIMMING POOLS, daycare, milk (resistant to chlorine tx)
Dx: stool ag or microscopy (modified acid fast, DFA)
Cryptosporidium parvum tx
live within intestinal epithelial cells antidiarrheal agents: Loperamide (opioid agonist) fluid management Nitazoxanide Paromomycin
Strongyloides stercoralis
Nematode
enter through exposed skin: bare feet on soil
often asx
can hatch eggs in SI ->autoinfection (persist for life)
GI sx, SOB, cough, perianal urticaria, migratory rash
Risk: rural, immunocompromised (hyperinfection), specifically HTLV1
Rhabditiform larvae in stool ** eggs not passed in stool
eosinophils in stool