Agents that destroy or inhibit protozoan parasites【252034413657465†L80-L110】
Explanation
Protozoa are unicellular eukaryotic organisms that live as free‑living microbes or as parasites in hosts. Parasitic protozoans such as Plasmodium, Entamoeba histolytica, Giardia lamblia, Trypanosoma and Leishmania cause diseases ranging from malaria and amoebic dysentery to sleeping sickness and leishmaniasis. Antiprotozoal drugs are compounds that kill (protozoocidal) or inhibit the growth and reproduction of these parasites【252034413657465†L80-L110】. Because protozoa share many cellular features with human cells, antiprotozoals target unique metabolic pathways or life‑cycle stages. Some agents inhibit nucleic acid synthesis or folate metabolism, others disrupt mitochondrial electron transport or anaerobic energy production, and some generate reactive metabolites that damage DNA. Antiprotozoal therapy must be tailored to the species and stage of infection, and treatments often combine agents to prevent resistance. Many antiprotozoals have narrow therapeutic windows and can cause adverse effects, so careful dosing and monitoring are required.
Examples and uses
Antimalarial drugs include chloroquine, quinine and artemisinin derivatives that target the blood stages of Plasmodium and primaquine, an 8‑aminoquinoline, used to eradicate dormant liver stages. Atovaquone–proguanil inhibits parasite electron transport and folate synthesis. Nitroimidazoles such as metronidazole and tinidazole are effective against anaerobic protozoa including Entamoeba and Giardia, producing radicals that damage DNA. Nitazoxanide, a nitrothiazole, interferes with pyruvate:ferredoxin oxidoreductase and treats cryptosporidiosis and giardiasis. Diamidines such as pentamidine and melarsoprol are used for early and late stages of African trypanosomiasis, whereas miltefosine and sodium stibogluconate treat leishmaniasis. Antiprotozoal therapy may be combined with antibiotics (e.g., trimethoprim–sulfamethoxazole for toxoplasmosis) or used in mass drug administration programmes to control endemic disease.
Antiprotozoal drugs play a critical role in managing parasitic diseases, but their efficacy depends on accurate diagnosis, proper dosing and ongoing surveillance for emerging resistance.
Related Terms: Protozoa, Antiparasitic, Anthelmintic, Antimalarial, Antimicrobials