Parasite Chemotherapy Flashcards
What are the characteristics of protozoa?
- Eukaryotic
- 80S ribosome
- metabolic pathways similiar to other animal cells
- cell membrane sterol- cholesterol
- no cell walls
What are the antimalarial antiprotozoal drugs?
quinone
chloroquine
primaquine
anitmetabolites
What are other antiprotozoal drugs (other than antimalarial)?
metronidazole
diloxanide
nifurtimox
suramin
(blank) is a mjor cause of death and illness throughout much of the world, particularly in Africa and Asia. Incidence is greater than 100 million cases per year.
Malaria
What is the parasite that causes malaria?
plasmodium sp.
What drugs are used to kill plasmodium?
it depends on the stage that the parasite is in.
What drug is used to kill plasmodium when it is in the tissues? (i.e exoerythrocytic stage)
primaquine
What drug is used to kill plasmodium when it is in the blood? (i.e erythrocytic stage)
chloroquine
quinine
diaminopyrimidines
mefloquine
Name the most common to least common forms of plasmodium?
P. vivax > P. falciparum > P. malariae > P. ovale (rare)
Why do the symptoms of malaria occur?
as a result of release of parasites into the blood stream.
What are the clinical signs of malaria?
fever, hemolysis, anemia, hypotension.
Malaria pathogenicity is a function of the degree of (blank) involvement.
erythrocyte
(bank) is highly pathogenic because it affects all erythrocytes. These infections are potentially lethal.
P. falciparum
P. vivax and P. malariae, which affect fewer red blood cells are (lethal/not lethal)
not usually lethal
In the mosquite, how do you kill sporontocides of malaria?
primaquine
proguanil
pyrimethamine
In humans, how do you kill tissue shizontocides (its in the liver) of malaria?
primaquine
proguanil
pyrimethamine
tetracycline
In humans, how do you kill hypozoiticides?
primaquine
In humans, how do you kill gametocytocides?
primaquine
How should you treat clinical malaria that has invaded your red blood cells as bood schizontocides?
chloroquine quinin, quinidine mefloquine artesunate sulfadozine and pyrimethamine halofantrine tetracycline
What was the first antimalarial drug?
Quinine (it was derived from the bark of the cinchona tree)
How do quinine work?
heme polymerization is blocked thus increasing heme concentrations to toxic levels (heme is toxic to parasites)The m
What are the adverse reactions of quinine?
cinchonism (a syndrome similiar to salicylate toxicity) curare effect myocarial depression vasodilation hemolytic anemia
When should you use quinine?
Used to treat chloroquine-resistant plasmodium falciparum
How does chloroquine work?
blocks plasmodial heme polymerization, increases heme concentrations. Heme is toxic to parasites!!!!
The mechanism of action is similar for all antimalarial quinolones except (blank).
Primaquine
Quinolines are weak (blank) that concentrate in food vacuoles of schizonts.
bases
(blank) forms of the malaria parasite are sensitive to chloroquine
erythrocytic forms
T or F
Resistant strains of falcparum have arisen and are vary common in Asia
T
How do malaria drugs get resistance to quinolines?
polygenetic mechanisms involving expression of transpot proteins that excrete the drug.
What is the clinical use of chloroquines?
used for prophylaxis (most common drug used) and treatment of acute attacks
What malarial parasites does chloroquine work on?
P. falciparum
Why doesn’t P. vivax get killed by chloroquine?
because P. vivax exists latent as exoerythrocyticin which is insensitive to drug
What are the adverse effects of chloroquine when you take it prophylactically?
prophylactic doses-little toxicity
What are the adverse effects of chloroquine when you take it in acute doses?
anorexia, nausea, vomiting, headaches, hemolytic anemia
What are the adverse effects of chloroquine when you take it in high doses (amebicidal)?
photosensitization, retinopathy, leukopenia
What are the clinical uses of chloroquine?
acute malarial attacks
prophylaxis of malaria
amebiasis
How does primaquine work?
binds to DNA, damages mitochondria, inhibits protein synthesis
What do you use primaquine for?
used to treat latent liver forms of P. vivax and P. ovale
What are the adverse reactions of primaquine?
same as chloroquine
hemolytic anemia
What is this:
Mechanism of action probably involves intercalation into DNA as well as oxidation of macromolecules. It induces oxidative stress in parasites and in host cells.
primaquine
Does primaquine work on erythrocytic forms of P. falciparum or P. malariae?
No
Why can primaquine cause hemolytic anemia?
cuz it is an oxidative stressor and when combined with a G6PD will cause hemolytic anemia
Where does primaquine work at?
oxidizes GSH to GSSG
(blank) and (blank) can be used alone or in combination to treat drug-resistant P. falciparum.
Artesunate
artemether
What is made up of the active components of a traditional chinese herbal antipyretic that is increasingly used outside the USA to treat drug-resistant P. falciparum. Not available in the US.
Aresunate and artemether (qinghaosu)
What is this?
a. Structurally similar to chloroquine and primaquine. Mechanism of action is similar to chloroquine.
b. Useful in treating chloroquine- and Fansidar-resistant strains of malaria. Effective against erythrocytic forms of the parasite.
mefloquinine
blocks plasmodial heme polymerization, increases heme concentrations. Heme is toxic to parasites!!!!
What are the adverse reactions of mefloquine (lariam)?
nausea, vomiting, bradycardia. Serious psychiatric disturbancese can occur (1:1000)
What are three antimetabolites used to treat malaria?
What are they effective against?
Chloroguanide
Pyrimethamine-sulfadoxine (fansidar)
Dapsone
erythrocytic forms of parasite
(blank) is a prodrug metabolized by the liver to dihydrotriazine which is a dihydrofolate reductase inhibitor.
chloroguanide
(blank) is a fixed dose combination of a dihydrofolate reductase inhibitor and a very long acting sulfonamide (t1/2 7-9 days).
Pyrimethamine-sulfadoxine (fansidar)
What is Pyrimethamine-sulfadoxine used on?
chloroquine resistant P. falciparum.
(blank) is a PABA analog also used to treat leprosy.
dapsone
What step gets inhibited by sulfadoxine?
What step does pyrimethamine inhibit?
What do these prevent from happening?
- pteridine and PABA becoming dihyropteroic acid
- dihydrofolic acid reduction to make dTMP
making folic acid for DNA production