Burkin: Parasitic Pharmacology

Question 1

What are these drugs used for?

Quinine
Chloroquine
Primarquine
Antimetabolites

Answer 1

Malaria

Question 2

What are other drugs used to treat protozoan parasites?

Answer 2

metronidazole
diloxanide
nifurtimox
suramin

Question 3

Which antimalarial drug is active against malaria when it is NOT in RBCs? What about when it is in RBCs?

Answer 3

primaquine; chloroquine and quinine

Question 4

Different antimalarial drugs act at different stages of the malarial parasite’s life cycle. Which drug works when the parasite is NOT within RBCs?

Answer 4

paraquine

Question 5

What is the method of action of quinine? What is it used to treat?

Answer 5

blocks heme polymerization so that heme concentrations are at toxic levels to parasites; used to treat chloroquine resistant Plasmodium falciparum

Question 6

What is an adverse reaction caused by quinine?

Answer 6

cinchonism (similar to salicylate toxicity), curare effect, myocardial depression

Question 7

How does chloroquine work? What is it used to treat?

Answer 7

blocks polymerization of heme, leading to toxic heme concentrations (toxic to parasites); works against ERYTHROCYTIC forms - used for acute malarial attacks, prophylaxis (prevention)

Question 8

What are the effects of chloroquine if used for prophylaxis? If used acutely? If used in large doses?

Answer 8

little toxicity; anorexia, vomiting, nausea, headache; photosensitivity, retinopathy, leukopenia

Question 9

How does primaquine work?

Answer 9

binds to DNA –> damages mitochondria via oxidative stress –> inhibits protein synthesis

Question 10

What is primaquine used for?

Answer 10

liver forms of P. vivax and P. ovale

**not very effective against P. falciparum or P. malariae

Question 11

Adverse reactions for primaquine?

Answer 11

same as chloroquine + hemolytic anemia

Question 12

What types of patients are particularly prone to hemolytic anemia while taking primaquine?

Answer 12

those with G6PDH deficiency

Question 13

How does pyrimethamine-sulfadoxine work?

Answer 13

inhibits dihydrofolate reductase (in PABA/DHF/THF pathway) - no folic acid synthesis - can’t form DNA

Question 14

What is the pathway that takes PABA to DNA and RNA?

Answer 14

PABA –> DHF acid via sulfadoxine
DHF –> THF via pyrimethamine
THF –> DNA and RNA

Question 15

What is pyrimethamine-sulfadozine used to treat?

Answer 15

cholorquine-resistant P. falciparum

Question 16

What is the mechanism of action of metronidazole?

Answer 16

prodrug that is activated by electron transport proteins in ANAEROBES and PROTOZOANS –> produces cytotoxic metabolites that damage DNA

Question 17

What is metronidazole used for?

Answer 17

amebiasis
trichomoniasis
giardiasis
anaerobic bacterial infections

Question 18

What is one adverse effect to keep in mind when talking about metronidazole?

Answer 18

potentially mutagenic to fetus

Question 19

What is the mechanism of action of Nifurtimox? What is it used for?

Answer 19

oxidative damage to DNA; Chagas disease

Question 20

What is the mechanism of action of suramin? What is it used for?

Answer 20

inhibits multiple enzymes, esp enzymes important for energy metabolism; African trypanosomiasis (pre-CNS)

Question 21

What is the most common helminthic parasite infection?

Answer 21

ancylostoma and necator (hookworms)

Question 22

What is praziquantel used for? Method of action?

Answer 22

broad spectrum for cestodes (tapeworm) and flukes; massive Ca++ influx causes muscle contraction of parasite

Question 23

Side effects of praziquantel?

Answer 23

nausea
vomiting
abdominal pain

Question 24

What is bithionol used for? Adverse effects?

Answer 24

alternative to praziquantel - uncouples oxidative phosphorylation - used for lung and liver fluke infections; causes nausea, vomiting, diarrhea, rashes, photosensitivity

Question 25

This drug us useful in treating chloroquine and Fansidar-resistant strains of malaria

Answer 25

mefloquine

Question 26

What are two antimetabolites used to treat malaria

Answer 26

chloroguanide | pyrimethamine-sulfadozine (fansidar)

Question 27

Three drugs used to treat Entamoeba histolytica

Answer 27

Paramomycin Iodoquinol Diloxanide furoate

Question 28

List four very important nematodes

Answer 28

Tricuris trichuria - whipworm Ascaris lumbricoides - roundworm Ancylostoma duodenale - hookworm Strongyloides stercoralis - threadworm

Question 29

How does mebendazole work? What is it used for?

Answer 29

binds to tubulin and disrupts microtubules; used broad spectrum - for trichuriasis, hookworms, enterobiasis, ascariasis

Question 30

Should mebendazole/albendazole be taken during pregnancy?

Answer 30

no - potential teratogen

Question 31

How does albendazole work? What is it used to treat?

Answer 31

disrupts microtubules; used for Strongyloidiasis; trichurasis; capillariasis, ascariasis, filariasis, toxocariasis; Taenium Solium and Cysticercus cellulosis; Echinococcosis (hydatid disease)

Question 32

How does thiabendazole work? What is it used to treat?

Answer 32

binds to tubulin, also blocks helminth specific enzyme fumarate reductase; used to treat Strongyloidiasis

Question 33

What are the filarial worms, or roundworms?

Answer 33

Trichinella spiralis Wucheria bancrofti Onchocerca volvulus Brugia malayi

Question 34

What drug is used for tissue and blood nematodes (filariasis)?

Answer 34

diethylcarbamazine

Question 35

How does Ivermectin work? What is it used to treat?

Answer 35

tonic paralysis of musculature via Cl- channels opening; used for nematodes (Onchocerciasis, enterobius, strongyloides, trichuris, ascaris)