Antiprotozoal Agents Flashcards
These parasitic infectious organisms can all be treated with what?
- Amebiasis (Entamoeba histolytica
- Trichomoniasis (T. vaginalis)
- Giardiasis (Giardia lamblia)
Metronidazole
What is the name for worm diseases?
Helminthic
These worms can all be treated with what agent?
- Hookworm (Necator americanus)
- Roundworm (Ascariasis)
- Pinworm (Enterobiasis)
Albendazole
Hookworm (Necator americanus) is found where in the US?
Southeastern US
Roundworm (Ascariasis) is found where in the US?
Appalachia
Gulf Coast
Pinworm has the most cases out of the three worms French presented to us at how many million? Cases mostly seen in which population?
42 million
Children
** Can be treated with albendazole but ALSO Pyrantel
Malaria can infect which two areas of the body? Which has higher mortality?
Blood (erythrocytic) = P. falciparum
Liver (exoerythrocytic) = P. vivax, P. ovale
*Blood has highest mortality, responsible for 85% of deaths
What is important to consider when treating malaria?
Resistance patterns of geographic regions
*P. falciparum (blood) chloroquine resistance becoming more prevalent
What is the vector for malaria?
Plasmodium-infected mosquitos
You have a pt traveling to Mexico-Caribbean and wants PROPHYLAXIS tx for malaria. What should you know about this area and what is the tx?
Mexico/Caribbean is chloroquine SENSITIVE
Tx: chloroquine 1-2 wks prior to travel and 4 wks after
You have a pt traveling to South America (South Africa and Asia to be specific) and wants PROPHYLAXIS tx for malaria. What should you know about this area and what is the tx?
South Americas (South Africa and Asia) are chloroquine RESISTANT
Tx: Atovaquone/proguanil daily 1-2 days prior travel and 1 wk after
Doxycycline: daily 1-2 days prior and 4 wks after
Mefloquine: Weekly 1-2 wks prior and 4 wks after
Tx for non-falciparum (i.e. P. ovale and P. vivax)
Tx (acute): Chloroquine
Tx (resistant): Mefloquine or atovaquone-proguanil or quinine + doxycycline
*Liver form (aka hypnozoite) to prevent relapse = Primaquine
Tx for P. falciparum?
Artemisinin combinations PLUS mefloquine OR sulfadoxine-pyrimethamine
OR
atovaquone-proguanil OR quinine + doxycycline or clindamycin
*Don’t forget P. falciparum has widespread chloroquine resistance
Tx for SEVERE P. falciparum?
artemisinin IV OR quinine/quinidine IV + antimicrobial
What is the mechanism of action (MOA) of chloroquine?
Interferes with feeding mechanism of parasite by raising blood pH (alkaline).
*Selective toxicity depends on drug concentration in parasite (25X plasma level)
How is chloroquine absorbed and what would you tell your pts to avoid while dosing?
Rapid and complete oral absorption
Tell pts to avoid antacids as it hinders absorption
Where does chloroquine concentrate in the body?
Liver and kidneys, has large Vd (volume distribution) therefore needs LOADING DOSE
What method of administration do you NOT give chloroquine?
IM = hypotension, shock, sudden death
- high total doses over 100 grams = ototoxicity, myopathy and IRREVERSIBLE retinopathy
- Children especially sensitive to toxicities
Mefloquine is related to quinine and is less toxic, but was given a black box warning in 2013 which contraindicates use for who?
Pts w/ neurologic and psychiatric disorders
Also pts with heart conduction abnormalities
Of the quinolines which is the most toxic?
Quinine = narrow therapeutic window
- given parenterally for acute infection
- overdose = cardiotoxicity, blindness and deafness
Of the quinolines which is the least toxic?
Primaquine. It is also the most effective antimalarial
Good for radical cure (liver stages)
Who would you avoid giving primaquine to? Think of blood disorders.
G6PD deficiency = hemolysis
contraindicated in pregnancy
What is the MOA of primaquine?
Drug metabolites act as oxidants via unknown mechanism
What is the drug of choice for severe falciparum malarial infection?
artesunate IV (most rapid and potent onset)
Artemether PO after above therapy
What are some ADRs of artesunate? What do you monitor pts for after tx?
2-9% = acute renal failure, sepsis, coma, seizure, shock, respiratory failure
Monitor for 4 wks for possible severe post-tx hemolytic anemia
