Pharmacogenetics in Clinical and Forensic Toxicology: Opioid Overdoses and Deaths

Factors considered in the observed variability in drug response within a population are intrinsic, extrinsic, or a combination of both. The intrinsic factors are differences in the demographics of a given individual (e.g., age or gender), disease or physical condition (e.g., renal function or BMI), and pharmacogenetics (see below). The extrinsic factors are composed of environmental factors (e.g., diet) as well as drug interactions or polypharmacy.