Pharmacokinetic properties

Pharmacokinetics is the mathematical characterization of the time course of drug absorption, distribution, metabolism, and excretion. Over the past 50 years, dramatic scientific advances have revolutionized drug development and design and clinical decision making. These include improvements in quantitating drug and metabolite concentrations in biologic matrices (plasma and tissue), measuring drug effects, and understanding how genetics, metabolic pathways, and drug transporters influences drug disposition. A major challenge for health-care professionals in clinical psychopharmacology is in understanding and adjusting for individual differences in a drug’s response. Knowledge of a drug’s pharmacokinetic characteristics can be leveraged to help resolve these issues and formulate rational drug therapy decisions. As an example, understanding the absorption and distribution characteristics of a drug allows one to predict the amount of an administered dose that is expected to enter the bloodstream and reach its site of action. Further, an understanding of drug metabolism and elimination allows for the prediction of drug concentrations when it is administered on a repeated basis (i.e., under steady-state conditions); this allows for the rational selection of dosing regimens. Dose and regimen selection must also take drug interactions, genetic polymorphisms, comorbid conditions, and aging into account since all of these can impact drug exposure, efficacy, and toxicity.