Antiprotozoals

Question 1

what are the 2 forms that E. histolytica can be

Answer 1

trophozoite- can’t survive outside the body
cyst- can be passed in feces, can survive outside the body

Question 2

what is the difference between luminal amebicides and systemic amebicides

Answer 2

luminal- act only on luminal parasites, not absorbed from GIT
systemic- act only on tissue amoebas, completely absorbed from GIT

Question 3

what are the most commonly used anti-amebic drugs

Answer 3

metronidazole
tinidazole

Question 4

what type of effect do mixed anti-amebic drugs such as metronidazole and tinidazole have

Answer 4

mixed- effect in luminal and tissue forms

Question 5

is metronidazole or tinidazole longer acting

Answer 5

tinidazole

Question 6

what is the mechanism of action of metronidazole

Answer 6

it accepts electrons from ferredoxin in anaerobic conditions and converts it to reduced cytotoxic intermediates

the reduced form causes breaks in DNA

Question 7

metronidazole is the drug of choice in what 2 protozoal infections

Answer 7

amebiasis
giardiasis

Question 8

metronidazole is the drug of choice in what 3 bacterial infections

Answer 8

B. fragilis
C. difficile (has been replaced by vancomycin)
H. pylori

Question 9

what are the 5 main adverse effects of metronidazole

Answer 9

peripheral neuropathy
seizures
pancreatitis
thrush
disulfiram like reaction

Question 10

__ can alter the effect of metronidazole

Answer 10

enzyme inducers and inhibitors

Question 11

what are the advantages of tinidazole over metronidazole (2)

Answer 11

longer acting
less adverse effects

Question 12

can tinidazole only be used in protozoal or anaerobic bacterial infections, unlike metronidazole which can be used for both

Answer 12

protozoal

Question 13

Paromomycin is effective in __ infection and useful as an alternative

Answer 13

Giardia lamblia

Question 14

is idodquinol luminal or systemic

Answer 14

luminal

Question 15

what are the adverse reactions of iodoquinol

Answer 15

nausea/vomiting
optic neuritis

Question 16

what is the mechanism of action of nitazoxanide

Answer 16

inhibits pyruvate ferredoxin oxidoreductase

Question 17

nitazoxanide is most effective for what 2 types of infection

Answer 17

giardiasis
cryptosporidiosis

Question 18

chloroquine is used in amoebic __

Answer 18

liver abscess

Question 19

chloroquine is combined with what 2 other medications

Answer 19

metronidazole
paromomycin/idoquinol

Question 20

why is chloroquine not useful to treat luminal amebiasis

Answer 20

it is completely absorbed from the upper GIT

Question 21

what is the mechanism of action of emetine

Answer 21

inhibition of protein synthesis by blocking AA elongation

Question 22

is emetine luminal or systemic amebicide

Answer 22

systemic

Question 23

emetine is only used if other drugs are not effective or in severe __

Answer 23

intestinal, hepatic, and extraintestinal amebiasis

Question 24

what is the main adverse effect of emetine

Answer 24

cardiotoxicity

Question 25

emetine should be avoided in patients with what condition

Answer 25

cardiac arrhythmias

Question 26

what is the drug of choice for toxoplasmosis

Answer 26

pyrimethamine and sulfadiazine combo

Question 27

pyrimethamine and sulfadiazine combo used to treat toxoplasmosis can lead to what adverse effect

Answer 27

megaloblastic anemia

Question 28

pyrimethamine and sulfadiazine combo can be used for prophylaxis and treatment for what infction

Answer 28

toxoplasmosis (T. gondii)

Question 29

what is the drug alternative used to treat toxoplasmosis in those pregnant

Answer 29

spiramycin

Question 30

what are the 3 drug options for use in those with cryptosporidiosis

Answer 30

nitazoxanide paromomycin azithromycin

Question 31

what is involved in the clinical first vs second stage of Chages disease (American trypanosomiasis)

Answer 31

first- multiply in subcutaneous tissue, blood, and lymph second- cross BBB and infect CNS

Question 32

what is the main adverse effect of pentamidine

Answer 32

renal dysfunction

Question 33

what is the drug of choice for hemo-lymphatic (first) stage of T. brucei/W. African trypanosomiasis what else can be used

Answer 33

pentamidine suramin

Question 34

why is suramin not used for the second stage African trypanosomiasis

Answer 34

it does not cross the BBB

Question 35

what drug is used in the late stages (CNS/meningoencephalic stage) of East African trypanosomiasis

Answer 35

melarsoprol

Question 36

what is the main adverse effect of melarsoprol

Answer 36

fatal reactive encephalopathy

Question 37

what is used as the first line drug for west african trypanosomiasis

Answer 37

eflornithine or eflornithine in combination with NECT

Question 38

what is the mechanism of action of nifurtimox and benznidazole

Answer 38

form ROS and inhibit trypanothione reductase and DNA synthesis