Antiparasites Flashcards
what is unique about the treatment of parasite
you may have to eradicate multiples stages of parasite in the host (eg adults, larval or immature stages, ova)
What drugs can be used to treat round worm
- Mebendazole
- Albendazole
- Thiabendazole
- Pyrantel pamoate
Mebendazole
- for many intestinal round worms
- kills some ova (ascaris, trichuris, necator)
- poorly aborbed low systemic toxicity
Albendazole
labeled- Echinococcus
unlabeled-cutaneous larval migrans
-well distributed elevated hepatic enzymes, nausea, vomiting, headache
Thiabendazole
-labeled: Strongyloides
cutaneous larva migrans
(“disseminated dog or cat hookworm)
- oral or topical if limited
- rapidly abosrobed; nausea vomiting dizziness
Pyrantel Pamoate
- hookworm, pinworm, and round worm (Ancyclostoma, Necator, Enterobius, Ascaris)
- OTC as Pin-X for pinworm
- NOT for whipworm (trichuris)
- poorly absorbed: mild GI symptoms
Praziquantel
- use
- side effects
- drug of choice for Schistosoma
- some activity against other trematodes
-SE: abdominal discomfort, nausea
Praziquantel and cestodes
- good activity for many cestodes
- for taenia solium because it also kills eggs (which are infective to man) thereby preventing cysticercosis
Albendazole- cestodes
-treat neurocysticercosis
Paromycin sulfate
-3rd choice for cestodes
Antimalarial drugs
- none of the drugs prevent infection
- drugs only prevent progression to symptomatic malaria ( this is wht is meant by prophylaxis)
after leaving an endmeic area of P. vivax and ovale
target the hepatic form 14 days after leaving an endemic area for P viviax and ovale
How do you treat while you are in an endemic area for all four malaria species , and how long do you continue this treatment
-For all four species, target RBC forms while in endemic area, and continue for four weeks after leaving the endemic area
Chloroquine
- blood schizonte
- parasitized erythrocytes concentrate the drug (over 255 fold) by pH dependent mechanisms into acidic vacuoles
- Chloroquine is a weak base that is non-charged at physiologic pH. Therefore, it freely crosses the membrane into the erythrocyte, then into the parasite inside the erythrocyte, then into the vacuole inside the parasite. Once its in the vacuole it is protonated, and therefore charged. now it can’t cross the membrane and leave the vacuole so the drug gets concentrated in the vacuole. Which is great bc that is where the parasite stores heme/ breaks it down to release amino acids. While doing this that also causes heme release and free heme is toxic bc it produces oxygen radicals. But the parasite has an enzyme that detoxifies heme. Chloroquine however inhibits this enzyme so there is a build up of toxic heme which leads to build up of oxygen radicals and then parasite destruction.*
- only intraerythrocytic trophozoites are sussepticle
- chloroquine inhibits heme polymerization allowing heme to accumulate to toxic levels
Chloroquine uses
- malaria prophylaxis: all 4 species of malaria provided that they are chloroquine sensitive
- not effective for chloroquine resistant strains of P. falciparum and P vivax
- Malaria treatment: eradicate P malariae and Chloroquine-sensitive P. falciparum
- target blood schizonts of P. vivax or ovale
- does not target liver hypnozoites (latent liver form)
