Final answer:
Antiprotozoan drugs target protozoa through antimetabolite and DNA-interfering mechanisms. Antihelminthic drugs disrupt microtubules, neuronal transmissions, ATP formation, and RNA synthesis. Antifungal drugs disrupt cell membrane integrity or ergosterol synthesis.
Step-by-step explanation:
Antiprotozoan drugs target infectious protozoa through several mechanisms. Some drugs function as antimetabolites, disrupting the synthesis of essential molecules in the protozoan cells. For example, atovaquone and proguanil interfere with electron transport and folic acid synthesis, respectively. Other drugs, like nitroimidazoles, cause DNA strand breakage. Similarly, antihelminthic drugs disrupt microtubule formation, block neuronal transmissions, inhibit ATP formation, induce spasms and paralysis, and interfere with RNA synthesis in schistosomes. Antifungal drugs disrupt cell membrane integrity or interfere with ergosterol synthesis.