Anti-Parasitic Agents

Question 1

3 Broad targets for anti-parasitic therapy

Answer 1

Enzymes/processes only found in parasite - PFOR, folate synth

Enzymes/process found in both host and parasite but INDISPENSABLE ONLY TO PARASITE - purine salvage pathways

Common biochemical functions found in both, but with different pharmacologic properties - DHFR, microtubule disruption

Question 2

Giardia and Entamoeba histolytica have two forms

Answer 2

trophozoite form

cyst form - quiet, relatively dormant

Question 3

Metronizadole MOA

Major side effects?

Answer 3

reduced by PFOR enzyme - leads to PRODUCTION OF RADICALS THAT BIND TO PROTEINS AND DNA

DISULFIRAM like reaction
Metallic taste
headache
dry mouth

Question 4

Metronidazole better against trophozoite or cyst forms?

Answer 4

trophozoites

Question 5

Paramomycin and Iodoquinol very effective at eliminating?

Answer 5

Entamoeba histolytica - Trophozoites and Cysts

FROM THE LUMEN

Question 6

Cryptosporidiosis characteristics

Answer 6

water borne outbreaks

profuse watery diarrhea

MAY BE CHRONIC AND FATAL IN AIDS PATIENTS

Question 7

Nitazoxanide MOA

Administered as?

Answer 7

interference with PFOR enzyme - disrupts energy metabolism

Oral suspension

Question 8

Pneumocystis jirovecii tx

Answer 8

TMP-SMX

Question 9

Toxoplasma gondii tx

Answer 9

Pyrimethamine-Sulfadiazine

Question 10

Sulfonamides (2)

MOA

Answer 10

Sulfadiazine
Sulfamethoxazole

PABA ANALOGS - INHIBIT DHPS

Question 11

Diaminopyrimidines

Answer 11

pyrimethamine
trimethoprim

INHIBIT DHFR

Question 12

Quinine toxicities (2)

Answer 12

Cinchonism - tinnitus, hearing loss, headache, nausea, vomiting, visual disturbances

Hypoglycemia

poorest therapeutic:toxic ratio of all anti-malarials

Question 13

Mefloquine toxicity

Answer 13

severe neuropsychiatric reactions - .5% of patients receiving it for treatment (high doses)

Question 14

Primaquine MOA

Important for?

Major toxicity?

Answer 14

prodrug - activated by host metabolism

ONLY DRUG ACTIVE AGAINST LIVER HYPNOZOITE FORMS of P. vivax and ovale

HEMOLYSIS IN G6PD DEFICIENCY PATIENTS

Question 15

Malarone (two drugs)

Highly effective against?

Answer 15

combo of atovaquone and proguanil

P. falciparum

Question 16

Proguanil MOA

Answer 16

DHFR inhibitor

Question 17

Doxycycline major side effects?

Answer 17

photosensitivity
dermatitis
staining of teeth in children

Question 18

Artemisinins importantyl effect against?

Answer 18

MUTLI-DRUG RESISTANT STRAINS of P. falciparum

Question 19

Most anti-helminthics one of two MOA’s

Answer 19

inhibit mitosis in parasite

cause muscle paralysis in parasite

Question 20

Benzimidazoles (3)

characteristics?

Answer 20

Albendazole
Mebendazole
Thiabendazole - more absorbable - HIGH TOXICITY

others poorly absorbed

Question 21

Benzimidazole toxicity

Contraindicated in?

Answer 21

GI
CNS

PRIMARILY GI WITH ALBENDAZOLE AND MEBENDAZOLE

Pregnancy and children under 2

Question 22

Albendazole/Mebendazole effective against?

Answer 22

ascariasis, pinworm, hookworm, whipworm

Question 23

Thiabendazole effective against?

Answer 23

STRONGYLOIDES

cutaneous larval migrans

Question 24

Ivermectin MOA

Drug of choice for?

Answer 24

hyperpolarization of muscle cells - PARALYSIS

STRONGYLOIDES
River blindness, L. loa, filarial, W. bancrofti, B. malayi

Question 25

Pyrantel pamoate MOA

Used primarily for what type of worms?

Drug of choice for?

Answer 25

ACTIVATES CHOLINERGIC NICOTINIC RECEPTORS - paralysis

Intestinal worms

Pinworm - treat entire threshold

Question 26

Praziquantel MOA

Drug of choice for (3)

Answer 26

INCREASE CALCIUM PERMEABILITY - depolarization - paralysis

Flukes
Tapeworms
Cysticercosis