Pharmacology of GI Infections Flashcards
What 3 drugs can capable of treating C. Difficile?
What are their classes?
Vancomycin - glycopeptide
Metronidazole - 5-nitroimidazole
Fidaxomicin - macrolide
In what severity of CDI would Vancomycin be used?
What other level of severity will it treat?
Severe CDI - first line treatment for CDI
Mild CDI - equivalent to metronidazole
Given PO
In what severity of CDI would Metronidazole treat?
If PO route won’t work for the pt.
Given PO or IV
In what case would you give Fidaxomicin for CDI? Why?
Recurrent CDIs - Spares many anaerobic colonic flora
What is the life cycle of E. histolytica?
Trophozoite -> binucleated precyst -> tetranucleated cyst
What are the 2 therapeutic goals of treating E. histolytica and which drugs can assist in those goals?
- Eliminate the invading trophozoites - Metronidazole or Tinidazole
- Eradicate the intestinal carriage (the bug within the lumen) - Paromomycin or Iodoquinol
To ensure eradication of E. histolytica, metronidazole and tinidazole must be given with…
A luminal amebicide (Paromomycin or Iodoquinol). If not, the intraluminal bugs will just re-infect.
MOA of Iodoquinol
PKs
Which patients should cautioned about taking?
Unknown
90% retained in the intestine - good because we are treating the intraluminal bug
I- sensitivities
What is the major type of treatment given in a Giardia?
What is the first line Rx treatment?
What are 2 other options?
Supportive - correct fluid and E- abnormalities
Tinidazole
Metronidazole, Nitazoxanide
MOA of Nitazoxanide
What is unique about it?
Adverse effects?
Inhibition of pyruvate-ferrodoxin oxidoreductase enzyme
It is a prodrug
Flatulence, enlarged salivary glands, yellow eyes/urine
What drugs are given to treat Cryptosporidium parvum caused:
Diarrhea
Antimicrobial agents
Fluid management (none)
Anti-diarrheal: Loperamide
Anti-microbial agents: Nitazoxanide (preferred), Paromomycin
In a patient with HIV and a C. parvum infection, what should be given?
Antiviral therapy + nitazoxanide
Where does the life cycle of C. parvum occur?
Within intestinal epithelial cells
What class does nitazoxanide belong to?
What class does paromomycin belong to?
Nitazoxanide: no class
Paromomycin: aminoglycoside
Life cycle of Necatur americanus and Ancylostoma (hookworms)?
What other parasite has the same life cycle?
Penetrates skin between toes
Larvae travel to lungs (alveoli)
Larvae grow and are coughed up and swallowed
Adult worms develop in SI
Worms populate and release fertilized eggs
Eggs excreted in feces
Eggs hatch and larvae live in skin
Ascaris lumbricoides
Life cycle of Strongyloides stercoralis
Larvae in soil penetrates skin and travels to lungs
Larvae grow in lungs, are coughed up and swallowed to the SI
Mature worms produce eggs
Eggs DO NOT get passed in stool - can create an autoinfection!
In which patients may you see a severe auto-infection of Strongyloides infection?
Pts. on immunosuppressant meds - on prednisone and asthma
What is unique about the life cycle of Trichuris trichuria?
No larvae, no transit through the intestinal wall, no lung involvement, no eosinophilia, no auto-infection
Life cycle of Enterobius vermicularis
Eggs ingested, pinworms mature in the cecum and ascending colon
Females migrate to the perianal region to lay eggs (at night)
What drug has the most adverse effects of nematode treatment drugs?
Thiabendazole
The majority of anti-parasitic drugs eliminate pathogens by…
Paralysis of bugs - relies on pts. immune system to help clear it
Primary treatment of N. americanus and A. duodenale
Albendazole
Primary treatment of A. lumbircoides (2)
Albendazole
Mebendazole
Primary treatment of S. stercoralis
Ivermectin
Primary treatment of T. trichiura
Mebendazole
Primary treatment of E. vermicularis (3)
Albendozole
Mebendozole
Pyrantel pamoate
How does Schistosoma spp. invade humans?
Through intact skin!
Eggs must reach freshwater to hatch - adults may survive and release eggs for years
What is the treatment for Schistosoma?
Praziquantel
Praziquantel MOA
Paralysis - causes increased Ca++ permeability of worms’- CM
Immediate: headache, dizziness, drowsiness, lassitude
After a few days: low grade fever, pruritis, rash
What is the life cycle of cestodes (tapeworms)?
Pigs/cows ingest egg from field contaminated w/ human feces
Human ingests undercooked meat, tape worm matures in intestines
Where does D. latum live?
Raw freshwater fish
Echinococcus granulosus comes from…
What are formed in the intestined?
Dogs/sheep - ingested from their feces
Hyatid cysts
What 3 drugs are used for cestode therapy?
Praziquantel
Niclosamide
Albendazole
What is the only anti-parasitic will kill the bug, rather than paralysis?
Niclosamide - uncouples oxidative phosphorylation
Adverse effects of Metronidazole
GI sx
HA
Metallic taste**
Do not take w/ EtOH - will cause it to be vomited
