Pharmaceutical Pharmacokinetic / Pharmacodynamic Studies or PK / PD studies are techniques used in the study of pharmacology. Pharmacokinetic, commonly referred to as PK, is the study of what the body does and how it reacts to a drug. Conversely, pharmacodynamics, referred to as PD, is how the drug effects the body. PK and PD studies are commonly performed together as they both factor into the drug dosage, benefits, and negative side effects.
PK studies that look at how the body reacts to a drug commonly study how fast the body absorbs the drug, how it gets distributed throughout the body, whether or not the drug gets metabolized, and how quickly the body can or does eliminate it. PD studies that focus on how a drug interacts with the body look at the concentration of the drug in relation to effects on the body.
Pharmacokinetics is especially concerned with how the body absorbs a drug product and how the route it is administered through as well as the dose administered affect absorption. A common acronym for studying the time course of drug distribution that, which stands for liberation, which looks at the process of a drug product being released from its pharmaceutical state, absorption, which studies the process of how a substance enters the blood for circulation, distribution, how a substance disperses throughout the body, metabolism, the body’s recognition of a substance and the metabolites it creates in response, and excretion, the process of the body removing substances.
Pharmacodynamics is especially concerned with the relationship between the concentration of a drug and the effects on the body. PD pays close attention to the therapeutic window, or the amount of drug it takes to get an effect as well as the duration of action, or the length of time a drug is active in the body for.