GI Pharmacology For Parasitic Infections Flashcards
What is the MOA of Benzimidazoles?
-Bind to parasitic beta-tubulin, disrupt microtubular polymerizaion and microtubular depentdent processes (attachment and transport).
What are the three Benzimidazoles used in anti-helminthic treatment?
- Albendazole
- Mebendazole
- Thiabendazole (cutaneous only)
What is the absorption and bioavabiltiy of medendazole?
- Poor absorption and efficient metabolism.
- Low systemic exposure.
- Safe medication >2 y/o.
What is the absorption and bioavailability of Albendazole?
- Modest absorption, efficient metabolism.
- Low systemic exposure to parent drug, exposure to metabolites make it effective against tissue dwelling helminths and hydatid cysts.
What is the absorption and bioavaibility of Thiabendazole?
Systemic toxicity limits its use to cutaneous only for larval migrans.
What medication is indicated for infection with Enterobius Vermicularis (pinworm)?
Mebendazole.
Common infection in kids
What medication is indicated for infection with Necator americanus and Ancylostoma duodenale (hookworms)?
Albendazole
What medications are indicated for infections with Ascaris lumbricoides?
Albendazole or Mebendazole
What medication is indicated for infection with Trichuris trichirua (whipworm)?
Mebendazole (3 day course) or Albendazole
what medication is indicated for treatment of infection with Toxocara species (larval migrans)?
Albendazole
What are the side effects of albendazole and medendazole?
Both are teratogenic. Pregnancy class C medications
What medication is affective against hookworms, pinworms, and round worms but ineffective against Trichuris trichiura?
Pyrantel pamoate.
What is the MOA of pyrantel?
Depolarizing NM blocking agent. Causes persistent activation of nAChr and spastic paralysis of the worm.
What agent can be given for heavy ascaris infections because it paralyzes the worms prior to treatment with second agent?
Pyrantel pamoate
What is the bioavability and absorption of pyrantel pamoate?
Poorly absorbed from the GI tract, confines action to intraluminal GI nematodes only.
Can be used with caution in pregnant women and children <2.
What medication can be used in the treatment of intestinal Strongyloides and Onchocerciasis?
Ivermectin
What is the MOA of Ivermectin?
Activates Glurtamate gates chloride channels causing hyperpolarization and paralysis.
What is a contraindication to the use of Ivermectin?
In patients with a disruptive BBB (meningitis, trypanosomiasis) due to the fact that ivermectin can act on GABA-gated Cl channels.
What drug is used in the treatment of lymphatic filariasis?
Diethylcarbamazine.
Can only be obtained via CDC
What is the drug of choice for infections of adult tapeworms (taenia species and diphyllobothrium)?
Praziquantel
What is the drug of choice for larval forms of tapeworm infections (cysticercosis, echinococcus)?
Albendazole
What is a contra-indicated use for treatment of Praziquantel?
Ocular cysticercosis due to destruction of the organism in the eye leading to damage.
What is the drug of choice in the treatment of cystic hydatid disease due to echinococcus granulosus (dog tapeworm in humans)?
Albendazole.
What is a finding on microscopy of the schistomiasis eggs?
Pointed structure sticking out of the surrounding membrane
