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Flashcards in Pharm_Protozoan Deck (47):
1

Antifungal therapy: Amphotericin B

Mechanism: Binds ergosterol (unique to fungi); forms membrane pores that allow leakage of electrolytes Clinical use: Serious, systemic mycoses. Cryptococcus, Blastomyces, Coccidioides, Aspergillus, Histoplasma, Candida, Mucor (systemic mycoses). Intrathecally for fungal meningitis; does not cross blood-brain barrier. Toxicity: Fever/chills ("shake and bake"), hypotension, nephrotoxicity, arrhythmias, anemia, IV phlebitis ("amphoterrible"). Hydration reduces nephrotoxicity. Liposomal amphotericin reduces toxicity.

2

Antifungal therapy: Azoles (Fluconazole, ketoconazole, clotrimazole, miconazole, itraconazole, voriconazole)

Mechanism: Inhibit fungal sterol (egosterol) synthesis, by inhibiting the P-450 enzyme that converts lanosterol to egosterol. Clinical use: Systemic mycoses. Fluconazole for cryptococcal meningitis in AIDS patients (because it can cross blood-brain barrier) and candidal infections of all types. Ketoconazole for Blastomyces, Coccidioides, Histoplasma, Candida albicans; hypercortisolism. Clotrimazole and micronazole for topical fungal infections. Toxicity: Hormone synthesis inhibition (gynecomastia), liver dysfunction (inhibits cytochrome P-450), fever, chills.

3

Antifungal therapy: Caspofungin

Mechanism: Inhibits cell wall synthesis by inhibiting synthesis of β-glucan Clincal use: Invasive aspergillosis Toxicity: GI upset, flushing

4

Antifungal therapy: Flucytosine

Mechanism: Inhibits DNA synthesis by conversion to 5-fluorouracil Clinical use: Used in systemic fungal infections (e.g., Candida, Cryptococcus) in combination with amphotericin B Toxicity: Nausea, vomiting, diarrhea, bone marrow suppression

5

Antifungal therapy: Griseofulvin

Mechanism: Interferes with microtubule function; disrupts mitosis. Deposits in keratin-containing tissues (e.g., nails) Clinical use: Oral treatment of superficial infections; inhibits growth of dermatophytes (tinea, ringworm) Toxicity: Teratogenic, carcinogenic, confusion, headaches, ↑P-450 and warfarin metabolism

6

Antifungal therapy: Nystatin

Mechanism: Binds ergosterol (unique to fungi); forms membrane pores that allow leakage of electrolytes. Topical form because too toxic for systemic use. Clinical use: "Swish and swallow" for oral candidiasis (thrush); topical for diaper rash or vaginal candidiasis

7

Antifungal therapy: Terbinafine

Mechanism: Inhibits the fungal enzyme squalene epoxidase Clinical use: Used to treat dermatophytoses (especially onychomycosis - fungal infection of finger or toe nails)

8

Antihelminthic therapy mechanism: Diethylcarbamazine

Unknown

9

Antihelminthic therapy mechanism: Ivermectin

Intensifies GABA-mediated neurotransmission and causes immobilization. Does not cross the blood-brain barrier; therefore, no effect of humans.

10

Antihelminthic therapy mechanism: Mebendazole

Inhibits glucose uptake and microtubule synthesis

11

Antihelminthic therapy mechanism: Praziquantel

Increases membrane permeability to calcium, causing contraction and paralysis of tapeworms and flukes

12

Antihelminthic therapy mechanism: Pyrantel pamoate

Stimulates nicotinic receptors at neuromuscular junctions. Contraction occurs, followed by depolarization-induced paralysis. No effect on tapeworms or flukes.

13

Antiprotozoan therapy mechanism: Chloroquine

Blocks plasmodium heme polymerase, leading to accumulation of toxic hemoglobin breakdown products that destroy the organism

14

Antiprotozoan therapy mechanism: Mefloquine

Unknown

15

Antiprotozoan therapy mechanism: Melarsoprol

Inhibits sulfhydryl groups in parasite enzymes. CNS involvement.

16

Antiprotozoan therapy mechanism: Nifurtimox

Forms intracellular oxygen radicals, which are toxic to the organism

17

Antiprotozoan therapy mechanism: Pyrimethamine

Selectively inhibits plasmodial dihydrofolate reductase (best for P. falciparum). Drug of choice for toxoplasmosis when combined with sulfadiazine.

18

Antiprotozoan therapy mechanism: Quinine

For chloroquine-resistant species when used in combination with pyrimethamine / sulfonamide

19

Antiprotozoan therapy mechanism: Sodium stibogluconate

Inhibits glycolysis at PFK reaction

20

Antiprotozoan therapy mechanism: Suramin

Inhibits enzymes involved in energy metabolism. No CNS involvement.

21

DOC: Ancylostoma duodenale, Necator americanus (hookworms)

-bendazoles or pyrantel pamoate

22

DOC: Ascaris lumbricoides (giant roundworm)

-bendazoles or pyrantel pamoate

23

DOC: Babesia

Quinine, clindamycin

24

DOC: Clonorchis sinensis

Praziquantel

25

DOC: Cryptosporidium

Prevention (by filtering city water supplies); no treatment

26

DOC: Diphyllobothrium latum

Praziquantel

27

DOC: Dracunculus medinensis

Niridazole

28

DOC: Echinococcus granulosus

-bendazoles

29

DOC: Entamoeba histolytica

Metronidazole and iodoquinol

30

DOC: Enterobius vermicularis (pinworm)

-bendazoles or pyrantel pamoate

31

DOC: Giardia lamblia

Metronidazole

32

DOC: Leishmania donovani

Sodium stibogluconate Meglumine antimonate Pantamidine Amphotericin B

33

DOC: Loa loa

Diethylcarbamazine

34

DOC: Naegleria fowleri

Amphotericin has been effective for a few survivors

35

DOC: Onchocerca volculus

Ivermectin

36

DOC: Paragonimus westermani

Praziquantel

37

DOC: Plasmodium (vivax/ovale; falciparum; malariae)

Begin with chloroquine; if resistant, use mefloquine. Vivax/ovale - add primaquine for dormant forms in liver (hypnozoite)

38

DOC: Schistosoma

Praziquantel

39

DOC: Strongyloides stercoralis

-bendazoles or ivermectin

40

DOC: Taenia solium

Praziquantel (use -bendazoles for neurocysticercosis)

41

DOC: Toxocara canis

Diethylcarbamazine

42

DOC: Toxoplasma gondii

Sulfadiazine + pyrimethamine

43

DOC: Trichinella spiralis

-bendazoles

44

DOC: Trichomonas vaginalis

Metronidazole

45

DOC: Trypanosoma brucei, T. gambiense, T. rhodesiense

Suramin for blood-borne disease or melasoprol for CNS penetration

46

DOC: Trypanosoma cruzi

Nifurtimox

47

DOC: Wuchereria bancrofti

Diethylcarbamazine