Which of the following is NOT listed as a factor influencing medication response?

• A. Ethnicity
• B. Age
• C. Weight
• D. Gender

Answer: (A)

Understanding how drugs affect people starts with recognizing several patient characteristics that shape response. Age, weight, and gender are commonly cited factors because they influence how a drug is absorbed, distributed, metabolized, and eliminated. Age can alter organ function and metabolism; weight affects the amount of drug needed for an effective dose; gender can lead to differences in body composition and hormone-related metabolism.

Ethnicity, while it can play a role in drug response in some contexts due to genetic variations, is not listed as a factor in this particular set. In this standard framework, Ethnicity is the one not included, making it the correct choice for not being listed.