Antiprotozoals Flashcards
what are the 2 forms that E. histolytica can be
trophozoite- can’t survive outside the body
cyst- can be passed in feces, can survive outside the body
what is the difference between luminal amebicides and systemic amebicides
luminal- act only on luminal parasites, not absorbed from GIT
systemic- act only on tissue amoebas, completely absorbed from GIT
what are the most commonly used anti-amebic drugs
metronidazole
tinidazole
what type of effect do mixed anti-amebic drugs such as metronidazole and tinidazole have
mixed- effect in luminal and tissue forms
is metronidazole or tinidazole longer acting
tinidazole
what is the mechanism of action of metronidazole
it accepts electrons from ferredoxin in anaerobic conditions and converts it to reduced cytotoxic intermediates
the reduced form causes breaks in DNA
metronidazole is the drug of choice in what 2 protozoal infections
amebiasis
giardiasis
metronidazole is the drug of choice in what 3 bacterial infections
B. fragilis
C. difficile (has been replaced by vancomycin)
H. pylori
what are the 5 main adverse effects of metronidazole
peripheral neuropathy
seizures
pancreatitis
thrush
disulfiram like reaction
__ can alter the effect of metronidazole
enzyme inducers and inhibitors
what are the advantages of tinidazole over metronidazole (2)
longer acting
less adverse effects
can tinidazole only be used in protozoal or anaerobic bacterial infections, unlike metronidazole which can be used for both
protozoal
Paromomycin is effective in __ infection and useful as an alternative
Giardia lamblia
is idodquinol luminal or systemic
luminal
what are the adverse reactions of iodoquinol
nausea/vomiting
optic neuritis
what is the mechanism of action of nitazoxanide
inhibits pyruvate ferredoxin oxidoreductase
nitazoxanide is most effective for what 2 types of infection
giardiasis
cryptosporidiosis
chloroquine is used in amoebic __
liver abscess
chloroquine is combined with what 2 other medications
metronidazole
paromomycin/idoquinol
why is chloroquine not useful to treat luminal amebiasis
it is completely absorbed from the upper GIT
what is the mechanism of action of emetine
inhibition of protein synthesis by blocking AA elongation
is emetine luminal or systemic amebicide
systemic
emetine is only used if other drugs are not effective or in severe __
intestinal, hepatic, and extraintestinal amebiasis
what is the main adverse effect of emetine
cardiotoxicity
emetine should be avoided in patients with what condition
cardiac arrhythmias
what is the drug of choice for toxoplasmosis
pyrimethamine and sulfadiazine combo
pyrimethamine and sulfadiazine combo used to treat toxoplasmosis can lead to what adverse effect
megaloblastic anemia
pyrimethamine and sulfadiazine combo can be used for prophylaxis and treatment for what infction
toxoplasmosis (T. gondii)
what is the drug alternative used to treat toxoplasmosis in those pregnant
spiramycin
what are the 3 drug options for use in those with cryptosporidiosis
nitazoxanide
paromomycin
azithromycin
what is involved in the clinical first vs second stage of Chages disease (American trypanosomiasis)
first- multiply in subcutaneous tissue, blood, and lymph
second- cross BBB and infect CNS
what is the main adverse effect of pentamidine
renal dysfunction
what is the drug of choice for hemo-lymphatic (first) stage of T. brucei/W. African trypanosomiasis
what else can be used
pentamidine
suramin
why is suramin not used for the second stage African trypanosomiasis
it does not cross the BBB
what drug is used in the late stages (CNS/meningoencephalic stage) of East African trypanosomiasis
melarsoprol
what is the main adverse effect of melarsoprol
fatal reactive encephalopathy
what is used as the first line drug for west african trypanosomiasis
eflornithine or eflornithine in combination with NECT
what is the mechanism of action of nifurtimox and benznidazole
form ROS and inhibit trypanothione reductase and DNA synthesis
