Antiparasitic drugs Flashcards by David Sisa Gangai

Metronidazole - MoA

It inhibits nucleic acid synthesis by disrupting the DNA of microbial cells.

Inhibit pyruvate-ferredoxin oxidoreductase (PFOR)

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Metronidazole - Clinical use

Entamoeba histolytica
Giardia intestinalis (Giardia lamblia)
Trichonomas vaginalis

Anaerobic bacteria:
Bacteroides fragilis
Helicobacter pylori
Clostridium difficle

Amebiasis
Giardiasis
Trichonomiasis
Dracunculiasis by Dracunulus medinensis (Guinea worm infection)
Balantidiasis
Enterocolitis
Rosacea (acne rosacea)

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Metronidazole and Tinidazole - Contraindications

Contraindicated during first trimester of pregnancy

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Metronidazole and Tinidazole - Adverse effects

Metallic taste
Transient leukopenia
Thrombocytopenia

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Metronidazole and Tinidazole - Interactions

Increase effect of warfarin.

Ethanol: disulfiram-like reaction

Serum levels affected by drugs inhibiting/inducing CYP3A4.

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Tinidazole - Clinical use

Entamoeba histolytica
Giardia intestinalis (Giardia lamblia)
Trichonomas vaginalis

Anaerobic bacteria:
Bacteroides fragilis
Helicobacter pylori
Clostridium difficle

Giardiasis
Trichonomiasis
Amebiasis
Amebic liver abscess
Bacterical vaginosis

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Iodoquinol, Paromomycin, Diloxanide - Clinical use

Used alone to treat asymptomatic carriers of E. histolytica, but it must be used in combination with a tissue amebicide to treat patients with symptomatic disease, including amebic dysentery and liver abcess

Dientamoeba fragilis (Idoquinolol)

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Nitazoxanide - MoA

Noncompetative inhibitor of pyruvate-ferredoxin oxidoreductase

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Nitazoxanide - Clinical use

Cryptosporidium parvum
Giardia lamblia
Entamoeba histolytica

Cryptosporidiosis, giardiasis in immunocompetent persons

Ascariasis

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Quinine, Chloroquine, Mefloquinine - MoA

Inhibits nucleic acid synthesis/function during erythrocytic schizogony

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Chloroquine, Quinine - Clinical use

Chloroquinine
P. falciparum, prevention and treatment

Combination with primaquine to eradicate P. vivax or P. ovale

Quinine: Alternative to artesunate for severe malaria

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Chloroquine - Contraindications

Should be used cautiously in pregnant women because fetal damage has been reported

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Chloroquine - Adverse effects

Quinine - Adverse effects

Toxic overdose: Retinal damage and blindness
Exacerbation of psoriasis and pruritus

Cinchonizm

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Mefloquinine - Clinical use

Prophylaxis and treatment of falciparum malaria, where it is known to be effective

Combination with artesunate is a first-line therapy in parts of Southeast Asia and South America

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Mefloquinine - Adverse effects

Severe neuropsychiatric syndrome characterized by hallucinations, anxiety, confusion, seizures and coma

Leukopenia
Thrombocytopenia
Bradycardia and arrythmias

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Primaquine - MoA

Form quinones that oxidize and destroy schizont membranes

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Primaquine - Clinical use

Exoerythrocytic tissue stage of P. vivax and P. ovale in combination with chloroquine or other drugs

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Primaquine - Adverse effects and Contraindications

Hemolytic anemia in G6PD deficiency

G6PD deficiency

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Artesunate, Artemether - MoA

Form free radicals that attack heme and proteins in malarial parasites and inhibit erythocytic schizogony

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Artesunate - Clinical use

IV is 1st line for severe falciparum malaria (children + adults)
P. vivax

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Artemether - Clinical use

P. falciparum malaria

P. vivax

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Which drugs has the most rapid action of the current drugs against falciparum?

Artesunate and Artemether

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Atovaquone - MoA

Inh synthesis of pyrimidines and nucleic acid synthesis by selective inhibition of mitochondria electron transport in plasmodia

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Atovaquone - Clinical use

Prophylaxis and treatment of Chloroquine-resistant falciparum malaria in combination with proguanil

Alone: pneumocystitis jiroveci infections

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Atovaquone - Special considerations

Always in combo with proguanil or doxycycline for malaria.

Proguanil - MoA

Inh synthesis of pyrimidines and nucleic acid synthesis by inhibiting dihydrofolate reductase

Proguanil - Clinical use

Prophylaxis and treatment of Chloroquine-resistant falciparum malaria in combination with atovaquone

Pyrimethamine, Sulfadoxine - MoA

Pyrimethamine: Inh folic acid synthesis in plasmodia by blocking dihydrofolate reductase. Sulfadoxine: Inh folic acid synthesis in plasmodia by inhibiting dihydrofolate synthesis

Pyrimethamine, Sulfadoxine - Clinical use

Malaria | Toxoplasmosis (in combination)

Pyrimethamine, Sulfadoxine - Adverse effects

Skin rashes Megaloblastic anemia and other hematologic reactions Folate deficiency Severe hematologic abnormalities

Drugs for toxoplasmosis

Pyrimethamine + sulfadiazine | Spiramycin

Drugs for toxoplasmosis - Clinical use

Pyrimethamine + sulfadiazine: Toxoplasmosis in AIDS Spiramycin: Fetal toxoplasmosis

Which drug is used for pregnant women with toxoplasmosis?

Spiramycin

Drugs for pneumocystic jiroveci infection

``` Trimethoprim-sulfamethoxazole Atovaquone Pentamidine Dapsone Prednisone ```

Which drug is preferred for acutely ill patients with pneumocystis jiroveci infections?

Prednisone

Dapsone - Special considerations

In combination with trimethoprim/pyrimethamine

Pyrimethamine + sulfadiazine- Interactions

Lecovorin (folic acid) can be added to reduce hematologic effects.

Pentamidine - Adverse effects

``` Hematologic toxicity Ventricular tachycardia Edema Pancreatitis Bronchospasm Stevens-Johnsons syndrome ```

Pentamidine and Suramin - Clinical use

Early African trypanosomiasis (sleeping sickness), | Trypanosoma brucei

Melarsoprol and Eflornithine - Clinical use

Late African trypanosomiasis (sleeping sickness) against CNS manifestations

Nifurtimox - Clinical use

American trypanosomiasis (Chagas disease), Trypanosoma cruzi

Nifurtimox - Special considerations

Often combined with interferon-γ

Miltefosine - MoA

Inhibits enzymes for glycolipid metabolism of the surface of leishmania species

Miltefosine - Clinical use

Cutaneous and visceral leishmaniasis (kala-azar)

Miltefosine - Adverse effect

Reversible hepatic and renal toxicity

Albendazole and mebendazole - Classification

Benzimidazole compounds

Albendazole and mebendazole- MoA

Binds b-tubulin and inhibit its polymerization to form microtubules in the parasites. Makes it impossible for them to obtain glucose

Albendazole and Mebendazole- Clinical use

``` Both: Intestinal nematode infections: Ascariasis Capillariasis Hookworm (Ancylostoma and Necator) Pinworm (Enterobius vermicularis) Whiphworm (Trichuris trichuria) ``` Trichinosis (combined with corticosteroid to relieve inflammation) Albendazole: Cysticercosis (Pork tapeworm, Taenia solium) Echinococcosis Microsporidiosis

Albendazole and mebendazole - Contraindications

Contraindicated during pregnancy

Pyrantel - Classification

Pyrimidine derivative

Pyrantel - MoA and Clinical use

Activates nicotinic ACh receptors in somatic muscles of nematodes. Causes depolarizing neuromuscular blockade. Hookworm and pinworm infection

Ivermectin - Classification

Broad-spectrum anthelmintic drug

Ivermectin - MoA

Increases Chloride permeability of intervertebrate muscle cells. Cause hyperpolarization of the cell membrane and paralysis of pharyngeal muscles in helminths

Ivermectin - Clinical use

``` Active against nematodes Strongyloidiasis Onchocerciasis (River blindness) Cutaneous larva migrans (Hookworm) Loa loa (loiasis) Lymphatic filariasis (brugia malayi, Wuchereria bancrofti) Scabies ```

Diethylcarbamazine (DEC) - Classification

Piperazine derivative

Diethylcarbamazine (DEC) - MoA

Inhibits prostacyclin and prostaglandin E2 and I2 in both host cell and filariae. Blood vessel constriction and aggregation of host granulocytes.

Diethylcarbamazine (DEC) - Clinical use

Elephantiasis (Wuchereria bancrofti, Brugia malayi)

Diethylcarbamazine (DEC) - Adverse effects

Severe hypersensitivity reaction

Praziquantel - Classification

Isoquinoline derivative

Praziquantel - MoA

Increased calcium permeability of the tegument, and cause depolarization

Praziquantel - Clinical use

``` Schistosomiasis Tissue flukes: Chinese liver fluke (Clonorchis sinesis) Lung fluke (Paragonimus westermani) Tapeworms (cysticerosis). ```

Triclabendazole - Clinical use

Sheep liver fluke (Flasciola hepatica)

Bithionol - Clinical use

Alternative for sheep liver fluke and lung fluke (Paragonimus westermani)

Oxamniquine - Clinical use

Alternative to praziquantel for Schistosoma mansoni infections

Niclosamide - Clinical use

Alternative to praziquantel for cestode infections

Permethrin - Classification

Synthetic pyrethrin-like compound

Permethrin - MoA

Block sodium currents in neurons of parasites. Paralysis of the organism

Permethrin - Clinical use

Pediculosis (lice) | Scabies (mites)

Spinosad - MoA

Activate nicotinic ACh receptors, causing muscle contraction and paralysis

Spinosad - Clinical use

Head lice (pt over 4 years)