Antiprotozoal Drugs Med Class- Quiz 2 Flashcards
Parasite overview
-Parasites common in underdeveloped tropical and
subtropical countries where sanitary conditions, hygiene and control of transmission are not adequate
-Because of world travel—these diseases are NOT confined to specific geographical areas
-Many of these agents have serious toxic effects
-Most of these agents are NOT proven to be safe in pregnancy
How to diagnose parasites
-Diagnosis is made by isolating amoeba in the feces
How are antiprotozoal drugs classified?
Drugs are classified as:
luminal, systemic, mixed
amebicides according to
their site of action
-Luminal agents—affect the amoeba in the lumen of the bowel
-Systemic agents—effective against the amoeba in the intestinal wall and liver
-Mixed agents—work in both the lumen and systemic forms of amebiasis (although luminal
concentrations are too low to be used alone)
Metronidazole (Mixed Amebicide)
-Is the PROTOTYPE for mixed amibicides
-DOC to treat amebic infections (usually used WITH luminal amebicide)
-MOA: forms reduced cytotoxic
compounds that cause the death of Entamoeba histolytica
-Completely and rapidly absorbed after oral absorption and distributes well throughout the body
-Accumulates in hepatic disease
-ADEs: n/v, Epigastric distress, Abdominal cramps, METALLIC TASTE Oral yeast, Neurotoxicity—dizziness, vertigo, paresthesias (Dont take with alcohol)
-Other mixed amebicide:
Tinidazole (more expensive thus not used as often but similar efficacy)
Luminal Amebicides
-After treatment of invasive intestinal or extraintestinal amebic disease is
complete—a luminal agent, should be used to treat the asymptomatic colonized state
-2 options:
1. Iodoquinol
2. Paromycin
-Amoebicidal against E. histolytica
-ADEs—GI distress, diarrhea, rash
Systemic Amebicides
-Used for treating extraintestinal amebiasis, such as liver abscess and intestinal wall infections
-Chloroquine:
-Used with Flagyl to treat liver abscess
-After therapy, patient should be
given a luminal amebicide
-Also effective to treat malaria
Commonly Used Treatment Options for Parasites
- Asymptomatic cyst carriers–>
Iodoquinol OR Paromomycin - Diarrhea/dysentery Extraintestinal –>
Metronidazole + Iodoquinol OR
Paromomycin
- Diarrhea/dysentery Extraintestinal –>
- Amebic Liver Abscess–> Metronidazole+ Iodoquinol [or Paromomycin]
Malaria Overview
-Acute infection caused by 5 species of Plasmodium
-Transmitted to humans via the bite of the female Anopheles mosquito (WHY DO I FEEL LIKE THIS IS A TEST ?)
-Presentation is headache, fatigue, fever, chills and sweats
-P. falciparum is the most dangerous and primary cause of severe malaria
PRIMaquine ;)
-Oral agent that eradicates primary liver forms of Plasmodium and prevents recurring malarias
-This drug does NOT work on the blood form of malaria, and as a result cannot be used as monotherapy
MOA: act as oxidants that disrupt the
metabolic processes of the plasmodia mitochondria
-Well absorbed after oral dose
-ADE’s: Drug induced hemolytic
anemia, GI distress
-CI: pregnancy, RA, Lupus
Chloroquinone
-WAS the backbone of malarial therapy—but is now limited due to P. falciparum resistance
-Used MAINLY PROPHYLACTICALLY against malaria in travelers going to Chloroquine sensitive areas
-MOA: leads to lysis of the parasites and the RBC
-Rapidly and completely absorbed
after oral dose (Very large volume of distribution)
-Drug also penetrates the CNS and
crosses the placenta
-ADE: * At low doses in prophylaxis—very few
-At higher doses—GI upset, itching,
headaches, blurred vision
-Dilated eye exam should be done
with prolonged use—due to toxicity to the retina
-Discoloration of nail beds and mucous membranes can occur with chronic use
-CI: liver dysfunction, severe GI problems or neurologic disease
-Patients with psoriasis or porphyria should NOT take this drug—as it can provoke an acute attack
Atovaquone- Proguanil
-Combination agent for Chloroquine resistant strains of P. falciparum
-Used in the prevention and treatment of malaria for travelers from outside malaria-endemic areas (not routinely used)
-Take with food or milk to facilitate absorption
-ADEs—n/v, abdominal pain, headache, diarrhea, anorexia and dizziness
Mefloquine
-Effective agent to prevent all plasmodia, and for treatment when used in combination w/ artimenisin derivative
-MOA is unknown; widely distributed to tissues and well absorbed
-1/2 life: 20 days
-ADEs—at high doses—nausea, vomiting, dizziness, hallucinations and depression
-Because of the potential for neuropsychiatric reactions, this drug is usually reserved for treating malaria when other agents cannot be
used (can also cause cardiac arrest if taken with quinine)
Quinine
-Reserved for severe infections and
Chloroquine resistant malaria
-Usually given with Doxycycline, Tetracycline or Clindamycin
-Oral, well distributed
-ADE’s: Toxicity from Cinchona tree derivative–> N/v, tinintus, vertigo
-ADEs are reversible and not a reason to suspend treatment
-SUSPEND TREATMENT IF
HEMOLYSIS OCCURS
Artemisinin
-1 st line for MDR P. falciparum malaria
-Giving with another antimalarial is recommended to prevent resistance
-The antimalarial action of
Artemisinin derivatives involves
the production of free radicals
-Oral, rectal, IM and IV formulas
are available
-Short ½ life prevents use of these
drugs for prevention
-ADEs: n/v diarrhea, rash
Pyrimethamine
-Is a blood schizonticide that treats the active infection in humans and a sporonticide helps stop the spread of malaria by preventing mosquitoes from passing it to others.
-Not used alone to treat malaria
-Fixed dosed combinations with
Sulfadoxine
-Pyrimethamine + Sulfadoxine used to treat Toxoplasma gondii
-If megaloblastic anemia occurs with this during treatment—it can be
reversed with Leucovorin
