Anti-Protozooals

Question 1

How do we get malaria?

Answer 1

• sporozoites are transmitted through mosquito (vector) saliva into host. They go to the liver and then go on to infect the RBCs.
• remember vectors bite twice (once to get infected, and once to transmit).

Question 2

What is chloroquine (CQ)?

Answer 2

• 4-aminoquinolone that interferes with the malaria parasite’s (plasmodium) heme detoxification. It kills only the erythrocytic stage of infection.
• asexual malaria parasites flourish in host erythrocytes by digesting Hb in their acidic fluid vacuoles, a process that generates free radicals and heme (toxic to the parasite). However, they sequester heme as an insoluble unreactive malarial pigment called HEMOZOIN.

Question 3

What is quinine?

Answer 3

• similar to chloroquine (inhibits parasite’s heme detoxification).
• alkaloid derivative from Peruvian bark of Cinchona tree.

Question 4

What can quinine toxicity cause?

Answer 4

• cinchonism= tinnitus, headache, and dizziness
• hypoglycemia
• blackwater fever (can come from malaria also)= hemoglobinuria

Question 5

What is mefloquine?

Answer 5

• 4-methanolquinoline= highly effective blood schizonticide used for malaria.
• contraindicated in pts on B-blockers.

Question 6

What is a toxicity of mefloquine toxicity?

Answer 6

• neuropsyychiatric (dysphoria, somnolence, vivid dreams, encephalopathy, psychosis, depression, seizure).

Question 7

What is atovaquone?

Answer 7

• hydroxynaphthoquinone= inhibitis pre-erythrocytic development of parasite in liver and interferes with cytochrome electron transport and DNA replication.
• used for malarai (plasmodium), pneumocystis jiroveci, T. gondii, and Bebesia

Question 8

What is Proguanil?

Answer 8

biguanide that is metabolized via P450. Inhibits plasmodial dihydrofolate reductase.

Question 9

** What is malarone?

Answer 9

• combination of Atovaquone + Proguanil.

* not recommended in children, pregnancy or breast feeding women.

Question 10

What other drug can treat plasmodium (malaria)?

Answer 10

tetracycline (doxycycline)

Question 11

** What is primaquine?

Answer 11

• 8-aminoquionoline= effective against intrahepatic forms of plasmodium (malaria) and RELAPSING malaria (hypnozoite formation). It damages plasmodial mitochondria via oxidative stress.

Question 12

What is a problem with primaquine?

Answer 12

• causes hemolytic anemia in patients with G6PD deficiency.

- never give parenterally= marked hypotension.

Question 13

What are artemisinins?

Answer 13

• “sweet wormwood,” potent and rapidly acting blood schizonticide that inhibits calcium adenosine triophosphatase, destroying plasmodium via free radical release (attacks parasite cell membrane).
• used in other countries.
• induces P450

Question 14

What is sulfadoxine-pyrimethamine?

Answer 14

• limited use for malaria because of serious ADRs

Question 15

What is pyrimethamine?

Answer 15

• blocks synthesis of nucleic acid and folate in plasmodium and T. gondii.
• company raised price of this drug a few years ago causing issues.

Question 16

Can quinine induce abortion?

Answer 16

YES :(

Question 17

Besides plasmodium species, what are the other 2 intra-erythrocytic organisms?

Answer 17

Bebsia (pig borne) and Bartonella

Question 18

What 2 drugs can we use to treat COMPLICATED malaria?

Answer 18

1. Guinidine gluconate (IV) then switch to oral.

2. Artesunate

Question 19

Is there some immunity in malaria?

Answer 19

may be some but not a lot

Question 20

What is Dapsone?

Answer 20

• widely used Rx of leprosy, PCP, toxoplasmosis, and leishmaniasis.
• inhibits plasmodial dihydropteroate synthase, folic acid synthesis.

Question 21

What is dapsone syndrome?

Answer 21

• rash, fever, jaundice, and eosinophilia

Question 22

What is metronidazole?

Answer 22

• antibiotic used for anaerobic bacteria and protozoa. It forms free radical metabolites that causes DNA damage and death of organism.

Question 23

What can metronidazole toxicity cause?

Answer 23

• disulfiram-like effect= abdominal distress, vomiting, flushing, and headache with alcohol consumption.
• peripheral neuropathy
• enceophalopathy

Question 24

What is pentamidine?

Answer 24

inhibits DNA, RNA, protein, and phospholipid synthesis used for trypanosomiasis, pneumocystis jiroveci, and leishmaniasis

Question 25

For what is miltefosine used?

Answer 25

• leishmaniasis

Question 26

*** For what is nitazoxanide used?

Answer 26

• cryptosporidiosis and giardiasis

Question 27

For what is furazolidone used?

Answer 27

• giardiasis

Question 28

What parasite is paromycin (aminoglycoside) sometimes used?

Answer 28

• Entamoeba histolytica