Antiprotozoals

• Metronidazole:
  • Treats: Giardia lamblia, Entamoeba histolytica (amebiasis, liver abscess), Trichomonas vaginalis. (Remember GET on the Metro). Also anaerobic bacteria.
  • MoA: Forms toxic free radicals.
  • Side Effects: Disulfiram-like reaction with alcohol, metallic taste.
• Antimalarials:
  • Chloroquine: Treats sensitive Plasmodium species. (Side Effect: Retinopathy with long-term use).
  • Mefloquine: For chloroquine-resistant malaria; prophylaxis. (Side Effect: Neuropsychiatric disturbances).
  • Atovaquone-Proguanil: For chloroquine-resistant malaria; prophylaxis.
  • Artemisinins (e.g., Artesunate): For severe P. falciparum malaria (often IV).
  • Primaquine: Kills hypnozoites of P. vivax & P. ovale (liver stages). (Side Effect: Hemolysis in G6PD deficiency – must test!).
• Pyrimethamine (+ Sulfadiazine):
  • Treats: Toxoplasma gondii, Cystoisospora belli.
  • MoA: Inhibits folate synthesis. (Give with leucovorin).
  • Side Effect: Bone marrow suppression.
• Nitazoxanide:
  • Treats: Cryptosporidium, Giardia.
• Sodium Stibogluconate:
  • Treats: Leishmania spp. (Side Effect: Cardiotoxicity).
• Nifurtimox/Benznidazole:
  • Treats: Trypanosoma cruzi (Chagas disease).
• Suramin/Melarsoprol/Pentamidine:
  • Treats: Trypanosoma brucei (African Sleeping Sickness). Melarsoprol for CNS involvement (toxic).

Antihelminthics

• Benzimidazoles (Albendazole, Mebendazole):
  • Treats (Broad Spectrum): Enterobius (pinworm), Ascaris (roundworm), Trichuris (whipworm), Hookworms (Ancylostoma, Necator). Albendazole also for Strongyloides, neurocysticercosis (Taenia solium larvae), hydatid cysts (Echinococcus).
  • Helminths NOT well treated by typical benzimidazoles
    • Trematodes (Flukes): Such as Schistosoma (blood flukes) and liver/lung flukes.
      • Better drug: Praziquantel.
    • Adult Cestodes (Intestinal Tapeworms): Such as Taenia saginata (beef) or Diphyllobothrium latum (fish).
      • Better drug: Praziquantel. (Albendazole is used for larval tapeworms like neurocysticercosis).
    • Certain Filarial Nematodes: For conditions like River Blindness (Onchocerca) or Loiasis (Loa loa), and for rapidly clearing microfilariae.
      • Better drugs: Ivermectin or Diethylcarbamazine (DEC) are often primary.
  • MoA: Inhibits microtubule polymerization.
  • Side Effects: Generally few; Albendazole: possible liver enzyme elevation, pancytopenia (with high dose/long use). Mebendazole: teratogenic.
• Praziquantel:
  • Treats: Trematodes (flukes) like Schistosoma, Clonorchis, Paragonimus; Cestodes (tapeworms) like Taenia spp. (intestinal), Diphyllobothrium.
  • MoA: Increases calcium permeability in worms leading to paralysis.
• Ivermectin:
  • Treats: Strongyloides stercoralis (drug of choice), Onchocerca volvulus (River blindness). Also scabies, lice.
  • MoA: Activates glutamate-gated Cl- channels (paralysis).
  • Side Effect: Mazzotti reaction (in onchocerciasis).
• Pyrantel Pamoate:
  • Treats: Pinworms, roundworms, hookworms.
  • MoA: Depolarizing neuromuscular blocker (paralysis).
• Diethylcarbamazine (DEC):
  • Treats: Wuchereria bancrofti, Brugia malayi (lymphatic filariasis), Loa loa.
  • Side Effect: Reactions to dying microfilariae.

Ectoparasiticides

• Permethrin:
  • Treats: Scabies, Lice.
  • MoA: Neurotoxin (Na+ channel blocker).
• Ivermectin (Oral): Alternative for scabies, lice.