Pharmacokinetics and Pharmacodynamics
Pharmacodynamics (PD) is that the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The consequences can include those manifested within animals (including humans), microorganisms, or combinations of organisms (for ex: infection). Pharmacodynamics and Pharmacokinetics (PK) are the most branches of pharmacology, being itself a subject of biology interested in the study of the interactions between both endogenous and exogenous chemical substances with living organisms. Particularly, pharmacodynamics is that the study of how a drug affects an organism, whereas pharmacokinetics is that the study of how the organism affects the drug. Both together influence dosing, benefit and adverse effects. Pharmacodynamics is usually abbreviated as PD and pharmacokinetics as PK, especially in combined reference (for example, when speaking of PK/PD models). Pharmacodynamics places particular emphasis on dose–response relationships, that is, the relationships between drug concentration and effect. One dominant example is drug-receptor interactions as modelled by
L + RóLR
Where L, R, and LR represent ligand Where L, R, and LR represent ligand (drug) receptor and ligand-receptor complex concentrations, respectively. This equation represents a simplified model of reaction dynamics which will be studied mathematically through tools such as free energy maps.