Final answer:
Substance P antagonists, like aprepitant and fosaprepitant, block the activity of substance P and can help reduce pain, alleviate anxiety, and treat certain conditions.
Step-by-step explanation:
Substance P antagonists, such as aprepitant and fosaprepitant, are drugs that block or impede the activity of substance P at its receptor sites in the body. Substance P is a neurotransmitter that plays a role in pain processing, stress reactions, and other physiological functions.
By antagonizing substance P, these drugs can help reduce pain, alleviate anxiety, and treat certain conditions like chemotherapy-induced nausea and vomiting.