Pharmacodynamics
The effects or actions of a drug at the molecular, biochemical, and physiologic levels. It is derived from the Greek words "pharmakon," which means "drug," and "dynamikos," which means "power." All drugs exert their effects by interacting at the molecular level with biological structures or targets, causing a change in how the target molecule functions in relation to subsequent intermolecular interactions. Receptor binding, post-receptor effects, and chemical interactions are examples of these interactions. Examples of these interactions include drugs binding to an enzyme's active site, drugs interacting with cell surface signalling proteins to disrupt downstream signalling, and drugs acting through binding molecules such as tumour necrosis factor