The term "pharmacogenetics" refers to the study of:

Pharmacogenetics is defined as the study of how an individual's genetic makeup affects their response to drugs, which includes how genetics influence drug metabolism. This field of study examines the variations in genes that dictate the way medications are absorbed, distributed, metabolized, and excreted by the body. By understanding these genetic factors, healthcare providers can tailor drug therapies to patients, optimizing efficacy and minimizing adverse effects.

In contrast, placebo effects refer to the benefits that a patient experiences from a treatment which is not due to the drug itself but rather the psychological impact of believing they are receiving treatment. Drug interaction outcomes involve studying how different medications may affect each other's action within the body, which is separate from genetic influences. Enzyme activity, while related to metabolism, does not encompass the broader genetic variations that pharmacogenetics studies; it focuses specifically on the biochemical processes rather than the genetic context influencing those processes.