Anti-Protozoans

Question 1

Falciparum malaria

Answer 1

most common and severe

lethal

Question 2

Vivax/ovale malaria

Answer 2

milder form

relapse due to presence of dormant hypnosites that remain in liver

Question 3

Propyhlactic anti-malarials

Answer 3

Choroquine
Primaquine
*must be orally available, long half life, low toxicity

Question 4

Treatment anti-malarials

Answer 4

Artemether/lumefantrine
Primaquine
Chloroquine

Question 5

Gametocidal activity

Answer 5

Artemether and Primaquine

Question 6

Chloroquine

Answer 6

Blood stage antimalarial, mainly prophylaxis or pregnant to
Weak base trapped in acidic parasite food vacuole
Digestion of Hb to heme is toxic to parasite
Inhibit biocrystallization of heme to hemozin (accumulate toxic substance in the vacuole)
*resistance due to vacuolar efflux transporter

Question 7

Artemether

Answer 7

Oral, GI, short half life 1-3 hrs (NOT good for chemoprophylaxis)
Used in combo w/ others (Lumefantrine is Long-acting partner 4-5 days)
FIRST LINE ORAL TX MDR Falciparum malaria
IV replaced IV quinidine, inactive counterfeits
Adverse: neurotoxicity, embryotoxicity in animals

Question 8

Primaquine

Answer 8

Similar to chloroquine but works in liver
TERMINAL prophylaxis after completion of travel w/ vivax/ovals.
Adverse - Contraindicated in G6PD deficient patients (hemolyzing anemia)

Question 9

Common protozoan infections in the U.S.

Answer 9

Trichomoniasis (genital, STI)
Giardiasis (GI)
Amebiasis (GI)
Cryptosporidiosis (GI)

Question 10

Metroniadazole (Flagyl)

Answer 10

Systemic antiprotozoan
Prodrug converted to DNA-damaging metabolite by anaerobic organisms
Amebiasis - give w/ Luminal amebicide to eradicate luminal “survivors”
Anaerobic bacteria

Question 11

Paromomycin

Answer 11

Luminal, not absorbed from GI (only GI effects, no systemic)
Aminoglycoside that binds to 30S ribbosome subunit E. histolytica to inhibit protein synthesis
Tx: amebiasis, in combo w/ metronidazole for amebic colitis, dysentery

Question 12

Most common helminthic infection in U.S.

Answer 12

Enterobiasis (pinworm) - children 5-10 years

Intense anal itching

Question 13

Albendazole

Answer 13

Inhibits polymerization of B-tubular, prevent formation of cytoplasmic microtubules = disrupt nematode motility and uptake of glucose
Tx: Cestode infx - neurocysticerosis (pork tapeworm) and hyatid disease, Round worm infx - ascariasis, hookworm, toxocariasis
TX: PINWORM INFECTION - single 400mg dose, repeat 2 weeks later

Question 14

Praziquantel

Answer 14

Increases permeability of Trematoda and Cestode cell membrane to CA2+ = paralysis and death
Tx: Trematode, Cestode and alternative to Albendazole
Adverse: similar to Jarish-Herxheimer rxn - kills organism in one swoop and can make the patient feel dry sick due to all the dying worms (cytokines release)

Question 15

Pyrantel pamoate

Answer 15

Depolarizing neuromuscular blocking agent
Effective only within the GI tract (poor absorption)
Inhibition of AChE = spastic paralysis and expulsion
**Available OTC until can get Albendazole (not as effective as Albendazole)

Question 16

Ivermectin

Answer 16

Immobilization of worms by tonic muscle paralysis
Activates glutamate Cl- channel (only in invertebrates) = paralysis due TO HYPERPOLARIZATION
Broad spectrum - nematodes Arthropoda
Adverse - Mazzotti rxn (cytokines release - pruritis fever rash)
Teratogenic - cleft palate in pregnancy