What is the primary action of antiparasitic drugs?

Antiparasitic drugs primarily function by destroying parasites or inhibiting their growth, which is fundamental to their therapeutic purpose. These medications target various types of parasites such as protozoa, helminths (worms), and ectoparasites (like fleas and ticks).

The mode of action may vary depending on the specific antiparasitic agent used; some may interfere with the parasite's ability to reproduce, while others may disrupt their metabolic processes or cellular structures. For example, some drugs may inhibit essential enzymes in the parasite, ultimately leading to its death or halting its growth.

The other choices do not accurately capture the primary action of antiparasitic drugs. Enhancing the host's immune response refers more to immunomodulatory therapies rather than direct antiparasitic action. Promoting new cell growth and increasing nutrient absorption are unrelated to the antiparasitic effect, as these actions do not directly impact parasites or their life cycles. Therefore, the most accurate characterization of antiparasitic drugs is their ability to directly confront and control parasitic infections effectively.