Antiparasitics

Question 1

Chloroquine

Answer 1

Antimalarial - thought to inhibit heme polymerase which detoxifies ferri IX which is usually toxic to parasite; effects asexual and erythrocytic forms

Long 1/2 life (once/week prophylaxis)

Resistance imbued by polymorphisms in pfcrt gene, which encodes for transporter taking chloroquine out of acidic vacuole slowing effect of drug

Use: Prevent & treat plasmodia vivax, ovale, malariae, and sensitive falciparum

Adverse: exacerbation of psoriasis, retinopathy, hemolysis in G6PD deficiency, CYP2D6 inhibitor
not recommended for epilepsy or myasthinia gravis

Question 2

Primaquine

Answer 2

Antimalarial - may interfere with mitochondria; ONLY drug for exoerythrocytic forms of vivax and ovale (radical cure for this case)

Adverse: Hemolysis - G6PD deficiency(contraindicated)

Question 3

Quinine

Answer 3

Antimalarial - similar to choroquine

Adverse: poor theraputic/toxic ratio; CINCHONISM - tinnitus, hearing loss,

Question 4

Quinidine

Answer 4

Antimalarial - similar to chloroquine

Use: parenteral therapy of chloroquine resistant malaria, being replaced by artemisinins

Adverse: EKG changes, hypotension

Question 5

Meflaquine

Answer 5

Antimalarial - treatment & prophylaxis of drug resistant, schizonolcidal no effect on exoerythrocytic

Adverse: vivid dreams, neuropsychiatric symptoms

Question 6

Pyrimethamine

Answer 6

Antimalarial - binds and inhibits dihydrofolate reductase

Adverse: hypersensitivity, hematologic reactions, anemia due to decrease in folic acid

High resistance

Question 7

Malarone

Answer 7

Antimalarial - atovaqoune (mitochondrial toxic) & proguanil (inhibits dihydrofolate thymidylate synthase)

Use: effective against blood asexual forms and liver forms in falciparum but not vivax

Question 8

Artemisinin

Answer 8

Antimalarial - effective against P falciparum and erythrocytic stages of vivax

Use: combo with other drugs for severe P falciparum, not used for prophylaxis or in pregnancy

Question 9

Giardiasis

Answer 9

Most prevelant enteric parasite in the US

Treatment: Metronidazole 250mg TID x 5-7 days, or Tinidazole, Nitazoxanide in children

Question 10

Metronidazole

Answer 10

Amebicidic - nitro group serves as electron acceptor forming cytotoxic agent

Use: anaerobic bacteria, entamoeba histolytica, E. palecki, Girardia lamblia, trichamonas vaginalis

Adverse: metallic taste, alcohol intolerance

Question 11

Iodoquinol

Answer 11

Amebicidic - luminal activity for cyst elimination

Adverse: seizures, encepalopathy, high iodine content can interfere w/ TFTs

Question 12

Paromomycin

Answer 12

Amebicidic - aminoglycoside

Adverse: nephrotoxic, ototoxic

Question 13

Leishmaniasis

Answer 13

Drug of choice: antmonial agents
1. Sodium stiboglucanate
Alternatives: Amphoteracin B, Pentamidine

Question 14

Trypanosomiasis

Answer 14

South american (chagas) drug of choice: Nifurtimox

African (Sleeping sickness) drug of choice: Eflornithine, suramin
Alt: Pentamidine

Question 15

Toxoplasmosis

Answer 15

Drug of choice: pyrimethamine + sulfadiazine

Alt: pyrimethamine + clindamycin

Question 16

Mebendazole

Answer 16

Anthelmintic - selectively binds to helminthe tubulin causing immobilization and blocks glucose uptake

Adverse: Abdominal pain, low side effects at normal dose

Question 17

Ivermectin

Answer 17

Antihelmintic - GABA receptor agonist
Drug of choice for Strongyloidiasis

Adverse: minimal, GI complaints, drowsiness

Question 18

Pyrantel Pamoate

Answer 18

Antihelmntic - depolarizing neuromuscular blocker
Alt to albendazole or mebendazole in Ascariasis, hookworm, and pinworm

Adverse: GI, headache, drowsiness

Question 19

Thiabendazole

Answer 19

Antihelmintic - inhibits fumurate reductase

Alt. for Strongyloidiasis

Question 20

Praziquantel

Answer 20

Mx: increases trematodes cell permeability to calcium leading to paralysis
Use: all forms of Schistosomiasis, trematodes and cestatodes

Question 21

Niclosamide

Answer 21

Mx: decreased ATP production in tapeworm mitochondria
Use: Alt. to Praziquantel for cestodes