Parasitic Agents

Question 0

Malaria in the blood

Answer 0

Schizont

Question 1

Malaria is the liver

Answer 1

Merozoites

Question 2

What malaria drug works on the liver

Answer 2

Primiquine

Question 3

What malaria drugs works on the blood cycle

Answer 3

chloroquine and Artemisinins

Question 4

Drugs used for prophylaxis of malaria

Answer 4

Primaquine and Chloroquine

Question 5

Drugs used for treatment of malaria

Answer 5

Artemether/lumefantrine, Chloroquine, Primaquine

Question 6

What 2 drugs have significant gametocidal activity

Answer 6

Artemether and primaquine

Question 7

T/F: Blood stage antimalarials are ineffective against liver stage parasites

Answer 7

True

Question 8

T/F: We have drugs against sporozoites therefore we have a “true prevention”

Answer 8

False

Question 9

What malarial drug is a weak base that becomes trapped in acidic parasite food vacuoles (trapped in infected RBC). Digestion of hemoglobin liberates heme (hematin), which is toxic to the parasite. Inhibits biocrystallization

Answer 9

Chloroquine

Question 10

Resistance to chloroquine is due to

Answer 10

Mutated vacuolar efflux transporter (PfCRT)

Question 11

Therapeutic uses of chloroquine

Answer 11

Ineffective against most strains. Prophylaxis and treatment against sensitive strains during pregnancy

Question 12

Adverse rxns of chloroquine

Answer 12

Generally well tolerated for prophylaxis. Can cause pruritis, headache, and GI effects in treatment doses. High doses cause CV toxicity.

Question 13

Name an Artemisinins

Answer 13

Artemether- derived from chinese medicinal plant qinghao.

Question 14

MOA of artemether

Answer 14

Unclear- evidence suggests artemisinins are converted to toxic free radicals by heme

Question 15

Artemether has a _______ half life ________ absorbed in the GI tract so not useful for chemoprophylaxis.

Answer 15

Short, rapid

Question 16

Systemic antiprotozoal agent

Answer 16

Metronidazole- a prodrug that is converted to a DNA-damaging metabolite by anaerobic organisms

Question 17

Luminal antiprotozoal agent

Answer 17

Paromomycin

Question 18

Benzimidazole

Answer 18

Albendazole

Question 19

MOA of albendazole

Answer 19

Inhibits polymerization of parasite B-tubulin, preventing formation of cytoplasmic microtubules. Disrupts nematode motility and DNA replication. First pass metabolism to active form, albendazole sulfoxide.

Question 20

What drug is this?: Generally used in combo with other antimalarials. Fixed dose combo with lumefantrine which sustains antimalarial activity. A first line oral treatmnt of MDR faciparum malaria in endemic areas.

Answer 20

Artemether

Question 21

Adverse rxns of artemether

Answer 21

Safe reputation but:

1) Neurotoxicity
2) Potent embryotoxicity in animal models; humans unclear

Question 22

MOA and Therapeutic uses for primaquine

Answer 22

MOA: Unclear
Therapeutic: With chloroquine to achieve clinical and radical cure of vivax/ovale malaria. Terminal prophylaxis after completion of travel to vivax/ovale endemic areas. Primary prophylaxis against all species if other agents are inappropriate.

Question 23

Adverse effects of primaquine

Answer 23

Generally well tolerated in G6PD deficiency normal patients.
Prototype for drug-induced hemolytic anemia in G6PD deficiency.
Contraindicated in all G6PD deficient patients and in pregnant women.

Question 24

Therapeutic uses of metronidazole

Answer 24

Amebiasis, giardiasis, trichomoniasis. For amebiasis- given in combination with a luminal amebicide to eradicate luminal survivors.

Question 25

MOA of paromomycin

Answer 25

Aminoglycoside that binds to 30S ribosomal subunit of E.histolytica to inhibit protein synthesis; not absorbed from GI tract so is not effective systemically.

Question 26

Therapeutic uses of paromycin

Answer 26

Alone for asymptomatic amebiasis or in combo with metronidazole for amebic colitis/dysentery.
Alternative to metronidazole during 1st trimester in pregnant females being treated for giardiasis.

Question 27

Therapeutic uses for albendazole

Answer 27

Cestode infections
Roundworm infections
Pinworm infection

Question 28

Adverse rxns of albendazole

Answer 28

Teratogenic effects in animals; use should be avoided in pregnancy.
Long term use can cause liver toxicity

Question 29

MOA, Therapeutic uses, and adverse rxns of Praziquantel

Answer 29

MOA: Increases permeability of trematode and cestode cell membranes to calcium; results in paralysis, dislodgment, and death.
Therapeutic: Drug of choice for schistosomiasis and effective in treatment of most other trematode and cestode infections.
Adverse rxns: Generally well tolerated- not sure if symptoms (fever, pruritis, rash) are from drug or release of proteins from worm death.

Question 30

MOA for Pyrantel pamoate

Answer 30

Depolarizing neuromuscular blocking agent. Only effective in GI tract because poor absorption. Causes persistant activation of parasite nicotinic ACh receptors and inhibition of AChE; results in spastic paralysis followed by expulsion of the worms.

Question 31

Therapeutic uses for pyrantel pamoate

Answer 31

Available OTC and alternative to albendazole for ascariasis and enterobiasis

Question 32

Adverse rxns of pyrantel pamoate

Answer 32

Generally well tolerated- will produce neuromuscular blockade if given parenterally

Question 33

MOA for ivermectin

Answer 33

Immobilization of worms by tonic muscle paralysis.

a) Activates glutamate-gated Cl- channels found only in invertebrates.
b) causes hyperpolarization of cell membrane
c) P-glycoprotein efflux transporter pumps the drug out of mammalian CNS

Question 34

Therapeutic uses for Ivermectin

Answer 34

Broad spectrum agent used to treat infections by nematodes and arthropods in veterinary med.
Onchocerciasis (river blindness), lymphatic filariasis and intestinal nematodes in humans.

Question 35

Adverse rxns for Ivermectin

Answer 35

Generally well tolerated

• Mazzotti rxn- pruritis, rash, fever, lymphadema due o immune reaction to dying worms.
• Teratogenic (cleft palate) in animal studies- should be avoided in pregnancy

Question 36

Effective drugs against Pinworm

Answer 36

Benzimidazole or Pyrantel pamoate

Question 37

Effective drug against threadworm

Answer 37

Ivermectin

Question 38

Effective drug against Tapeworms and/or flukes

Answer 38

Praziquantel