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29 Cards in this Set

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Be able to list the categories (and sub-categories) of antiprotozal drugs and the drugs given in each category (subcategory).
Explain each drug MA and site of action, pharmacokinetics and adverse effects. Understand the rationale for a drug being used in a particular situation.
Be able to describe the life cycle of Entamoeba histolytica.
Be able to describe the life cycle of the malarial parasites.
Be able to differentiate amebiasis, malaria, trypanosomiasis, leishmaniasis, toxoplasmosis and giardiasis and any relevant subcategories of each.
Understand the concept of resistance and how this might effect a treatment for a condition.
Objectives
How is amebic dysentery caused by entamoeba histolytica diagnosed?
isolating E. histolytica from fresh feces.
entamoeba histolytica cysts are ingested --> ____________ form in ileum --> replicate in bowel walls --> can cause systemic infection (liver) --> _____ reform in rectum
entamoeba histolytica cysts are ingested --> trophozoites form in ileum --> replicate in bowel walls --> can cause systemic infection (liver) --> cysts reform in rectum
Classification of amebicidal drugs
Classification of amebicidal drugs

Luminal, Systemic, Mixed (luminal and systemic) luminal conc is too low to use "mixed" alone for lumen)
Metronidazole (FLAGYL)

_____ amebicide of choice for treating amebic infections.
Kills the E. histolytica trophozoites (not _____)
Broad spectrum of activity against protozoa and anaerobic bacteria.
Metronidazole activated when reduced by ferre______ or their equivalents in protozoa or bacteria.
The nitro group of metronidazole is able to serve as an electron ________, forming reduced cytotoxic compounds that bind to proteins and DNA leading to inhibition of protein synthesis and DNA strand breakage, resulting in cell death.
Metronidazole (FLAGYL)

Mixed amebicide of choice for treating amebic infections.
Kills the E. histolytica trophozoites (not cysts)
Broad spectrum of activity against protozoa and anaerobic bacteria.
Metronidazole activated when reduced by ferredoxins or their equivalents in protozoa or bacteria.
The nitro group of metronidazole is able to serve as an electron acceptor, forming reduced cytotoxic compounds that bind to proteins and DNA leading to inhibition of protein synthesis and DNA strand breakage, resulting in cell death.
Metronidazole

NOTE: for the treatment of amebiasis usu. admin. with a luminal amebicide, such as dil_______ f______, i_________, or paramo_____.(comb. provides cure rates > 90%.)
Metronidazole

NOTE: for the treatment of amebiasis usu. admin. with a luminal amebicide, such as diloxanide furoate, iodoquinol, or paramomycin.(comb. provides cure rates > 90%.)
Metronidazole

DOC mild-severe amebiasis, g_________, t_____________; also bacterial vaginosis
Metronidazole

DOC mild-severe amebiasis, giardiasis, trichomoniasis; also bacterial vaginosis
Metronidazole

Adverse effects: Most common assoc. with GI tract (N, V, epigastric distress, and abdominal cramps) Unpleasant ________ taste often experienced.
Other effects: Oral moniliasis (_____ infection of the mouth) and rarely neurotoxic problems (dizziness, vertigo, & numbness or paresthesias in the peripheral nervous system. If taken with alcohol a di________-like effect.
Contraind in 1st/Trim. pregnancy (mutagenic/carcinogenic/rats) and nursing women
DOC Clostridium difficile (pseudomem. colitis)
New: tinidazole (TINDAMAX) TID 5 days

CYP450 inhibitor (potentiates warfarin metabolism)
Metronidazole

Adverse effects: Most common assoc. with GI tract (N, V, epigastric distress, and abdominal cramps) Unpleasant metallic taste often experienced.
Other effects: Oral moniliasis (yeast infection of the mouth) and rarely neurotoxic problems (dizziness, vertigo, & numbness or paresthesias in the peripheral nervous system. If taken with alcohol a disulfiram-like effect.
Contraind in 1st/Trim. pregnancy (mutagenic/carcinogenic/rats) and nursing women
DOC Clostridium difficile (pseudomem. colitis)
New: tinidazole (TINDAMAX) TID 5 days

CYP450 inhibitor (potentiates warfarin metabolism)
how do you know if person on metronidazole has alcohol?
flushing, nausea, vomiting, SOB, tachycardia (hangover)
Does metronidazole cross the BBB?
yes
Iodoquinol (YODOXIN)

_______ amebicide, iodine compound, only 10% systemically absorbed
MA _______ ; 650 mg tid x 20d
Effects on cysts & trophozoites in GI, main use in asymptomatic cyst carriers and follow-up to metronidazole
GI disturbances, rash; high doses may cause enlarged _______, some neurotoxicity (neuropathy/visual disturbances)
Risk of optic neuritis, atrophy, possible loss of vision (rare, large doses over time)
Iodoquinol (YODOXIN)

Luminal amebicide, iodine compound, only 10% systemically absorbed
MA unknown ; 650 mg tid x 20d
Effects on cysts & trophozoites in GI, main use in asymptomatic cyst carriers and follow-up to metronidazole
GI disturbances, rash; high doses may cause enlarged thyroid, some neurotoxicity (neuropathy/visual disturbances)
Risk of optic neuritis, atrophy, possible loss of vision (rare, large doses over time)
Paromomycin (HUMATIN)

____(type)____ antibiotic; 25 mg/kg 3X per day x 7 days
Little PO absorption, _______ amebicide
Direct amebicidal effect (Inhibits protein synthesis leading to an effect on cell membranes – causing leakage)
Used in amebiasis, t________, g_________, c________________ (HIV) with limited effect
GI disturbances N-V-D, abd. pain; superinfection
Paromomycin (HUMATIN)

Aminoglycoside antibiotic; 25 mg/kg 3X per day x 7 days
Little PO absorption, luminal amebicide
Direct amebicidal effect (Inhibits protein synthesis leading to an effect on cell membranes – causing leakage)
Used in amebiasis, tapeworms, giardiasis, cryptosporidiosis (HIV) with limited effect
GI disturbances N-V-D, abd. pain; superinfection
Diloxanide Furoate (FURAMIDE)

_______ amebicide, 500 mg tid x 10d
MA _______, converted to active free ____ form in the gut
Usu used to treat asymptomatic ____ carriers and follow-up to metronidazole
Excessive __________, N-V-D, pruritis; dizziness/double vision less common
Not used much in US
Diloxanide Furoate (FURAMIDE)

Luminal amebicide, 500 mg tid x 10d
MA unknown, converted to active free base form in the gut
Usu used to treat asymptomatic cyst carriers and follow-up to metronidazole
Excessive flatulence, N-V-D, pruritis; dizziness/double vision less common
Not used much in US
Systemic Amebicides

These drugs useful for treating liver absesses or intestinal wall infections caused by amebas.
C__________
E______
Systemic Amebicides

These drugs useful for treating liver absesses or intestinal wall infections caused by amebas.
Chloroquine
Emetine
Chloroquine

Used in combination with _____________ and diloxanide furoate to treat and prevent amebic liver a________.
Eliminates trophozoites in liver abscesses (not useful in treating _______ amebiasis)
Also effective in treatment of M______
Chloroquine

Used in combination with metronidazole and diloxanide furoate to treat and prevent amebic liver abscesses.
Eliminates trophozoites in liver abscesses (not useful in treating luminal amebiasis)
Also effective in treatment of Malaria
Emetine (not given IV)

Emetine and dehydroemetine (______ alkaloids) are alternative agents for the treatment of amebiasis. They inhibit protein synthesis by blocking chain elongation.
__ injection preferred route.
Use limited by toxicities (dehydroemetine less toxic than emetine). Close clinical observation necessary.
Not to take > 10 days.

Ipecac make you __
Emetine (not given IV)

Emetine and dehydroemetine (ipecac alkaloids) are alternative agents for the treatment of amebiasis. They inhibit protein synthesis by blocking chain elongation.
IM injection preferred route.
Use limited by toxicities (dehydroemetine less toxic than emetine). Close clinical observation necessary.
Not to take > 10 days.

Ipecac make you yac
Emetine

Adverse effects: pain at injection site, transient nausea, ______toxicity (arrhythmias or congestive heart failure), neuromuscular weakness, dizziness, and rashes

this is only used as a "back-up" for pts in the ________
Emetine

Adverse effects: pain at injection site, transient nausea, cardiotoxicity (arrhythmias or congestive heart failure), neuromuscular weakness, dizziness, and rashes

this is only used as a "back-up" for pts in the hospital
Malaria

Acute infectious disease caused by 4 species of the protozoal genus P_________. Parasite transmitted to humans by the bite of a female _________ mosquito (thrives in humid swampy areas)
Plasmodium f_________
Plasmodium v____
Plasmodium m_______
Plasmodium o_____
Malaria

Acute infectious disease caused by 4 species of the protozoal genus Plasmodium. Parasite transmitted to humans by the bite of a female anopheles mosquito (thrives in humid swampy areas)
Plasmodium falciparum
Plasmodium vivax
Plasmodium malariae
Plasmodium ovale
Plasmodium falciparum

Most _________ species
Causes an acute, rapidly fulminating disease that is characterized by persistent high fever, orthostatic ____tension, and massive erythro_______ (an abnormal elevation in the number of red blood cells accompanied by swollen and reddish condition of the limbs).
Can lead to capillary obstruction and death if treatment is not instituted promptly.
Most dangerous species
Causes an acute, rapidly fulminating disease that is characterized by persistent high fever, orthostatic hypotension, and massive erythrocytosis (an abnormal elevation in the number of red blood cells accompanied by swollen and reddish condition of the limbs).
Can lead to capillary obstruction and death if treatment is not instituted promptly.
Plasmodium vivax

Causes a ______ form of the disease.
Causes a milder form of the disease.
Plasmodium malariae

Common to many ________ regions.
Plasmodium malariae

Common to many tropical regions.
Plasmodium ovale
______ encountered
Plasmodium ovale
Rarely encountered
Malaria

insect injects sporo______ --> become ____zoites in the liver --> RBCs invaded --> ______zoites form and replicate in RBC --> RBC explodes releasing ____zoites --> ______cytes form and insects pick them up
Malaria

insect injects sporozoites --> become merozoites in the liver --> RBCs invaded --> trophozoites form and replicate in RBC --> RBC explodes releasing merozoites --> gametocytes form and insects pick them up
Important Note:

Resistance acquired by the mosquito to insecticides, and by the parasite to drugs, has led to new therapeutic challenges (particularly in the treatment of P. __________).
Resistance acquired by the mosquito to insecticides, and by the parasite to drugs, has led to new therapeutic challenges (particularly in the treatment of P. falciparum).
Malaria Parasite Life Cycle Stages

Pre-____________ stage- bite injects sporocytes in blood and goes to liver (1st hr.)
__________cytic stage – in liver 10-14 days, forms ____zoites: 2nary tissue forms remain in liver/become dormant (P. vivax/ovale)
Erythrocytic stage – RBC: releases ____zoites every 3 or 4 days with fever
______cyte stage – sexual forms ingested by biting female mosquito
Malaria Parasite Life Cycle Stages

Pre-erythrocytic stage- bite injects sporocytes in blood and goes to liver (1st hr.)
Exoerythrocytic stage – in liver 10-14 days, forms merozoites: 2nary tissue forms remain in liver/become dormant (P. vivax/ovale)
Erythrocytic stage – RBC: releases merozoites every 3 or 4 days with fever
Gametocyte stage – sexual forms ingested by biting female mosquito
Malaria Parasite Life Cycle Info.

Only _______cytic parasites cause clinical illness.
In P. falciparum and P. malariae infection, only one cycle of liver cell invasion and multiplication occurs, and liver infection ceases spontaneously in less than _ weeks. Thus treatment that eliminates ____________ parasites will cure these infections.
In P. vivax and P. ovale infections, a dormant hepatic stage, the _____zoite, is not eradicated by most drugs, and subsequent relapses can therefore occur after therapy directed against erythrocytic parasites. Eradication of both erythrocytic and _______ parasites is required to cure these infections.
Malaria Parasite Life Cycle Info.

Only erythrocytic parasites cause clinical illness.
In P. falciparum and P. malariae infection, only one cycle of liver cell invasion and multiplication occurs, and liver infection ceases spontaneously in less than 4 weeks. Thus treatment that eliminates erythrocytic parasites will cure these infections.
In P. vivax and P. ovale infections, a dormant hepatic stage, the hypnozoite, is not eradicated by most drugs, and subsequent relapses can therefore occur after therapy directed against erythrocytic parasites. Eradication of both erythrocytic and hepatic parasites is required to cure these infections.
Note

Diagnosis of Malaria depends on laboratory ID of the parasites in ____ ____ _____ of peripheral blood smears.
Note

Diagnosis of Malaria depends on laboratory ID of the parasites in red blood cells of peripheral blood smears.
Classes of Antimalarial Drugs

Tissue ________icides: eliminate developing or dormant liver forms
_____ Schizonticides: act on erythrocytic parasites
______cides: kill sexual stages and prevent transmission to mosquitoes
No available agent can reliably effect a radical cure (elim both hepatic and erythrocytic stages).
All effective chemoprophylactic agents kill erythrocytic parasites before they grow sufficiently in number to cause clinical disease
Tissue Schizonticides: eliminate developing or dormant liver forms
Blood Schizonticides: act on erythrocytic parasites
Gametocides: kill sexual stages and prevent transmission to mosquitoes
No available agent can reliably effect a radical cure (elim both hepatic and erythrocytic stages).
All effective chemoprophylactic agents kill erythrocytic parasites before they grow sufficiently in number to cause clinical disease
Strategies for Prevention and Treatment

Kill the mosquitoes
Don’t get stung by the mosquitoes
Prophylaxis – blood schizonticides (ery. cycle) used for suppressive prophylaxis, prevent symptoms of disease, not infection
Clinical cure – blood _______ticides (ery. cycle) used to kill all erthrocytic forms
_______ cure – elimination of all erythrocytic and secondary tissue forms
With P. falciparum/P. malariae clinical cure is a _______ cure
Strategies for Prevention and Treatment

Kill the mosquitoes
Don’t get stung by the mosquitoes
Prophylaxis – blood schizonticides (ery. cycle) used for suppressive prophylaxis, prevent symptoms of disease, not infection
Clinical cure – blood schizonticides (ery. cycle) used to kill all erthrocytic forms
Radical cure – elimination of all erythrocytic and secondary tissue forms
With P. falciparum/P. malariae clinical cure is a radical cure