Chapter 4

Pharmacodynamics

Drugs are chemical substances that modify biological responses by interacting with macromolecular targets such as receptors, ion channels,…

Drugs target macromolecules to modify ongoing cellular processes. Primary drug targets include receptors, ion channels, transporters, and…

Cells respond to many types of information, often through receptor proteins positioned on the membrane. They respond to chemical signals, such as…

G Protein–Coupled Receptors (GPCRs) are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an…

Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They…

Enzyme-linked receptors are cell-surface receptors acting as an enzyme or associating with an enzyme intracellularly. They make excellent drug…

Nuclear receptors, or NRs, are unique transcription factors that regulate gene transcription and affect the cellular pathways involved in…

Agonists can bind with and activate receptors, resulting in the formation of drug-receptor complexes. Once formed, these complexes catalyze many…

The potency of a drug is the measure of its ability to produce a biological response and can be compared by looking at the half-maximum effective…

Drugs exert their therapeutic effects by interacting with receptors, enzymes, or ion channels that are present throughout the human body. The…

The therapeutic index of a drug is a key parameter in pharmacology that quantifies the relative safety of a drug by calculating the ratio between the…

Agonists are drugs that interact with specific receptors in the body to produce a biological response. When an agonist binds to a receptor, it…

An antagonist is a drug that binds strongly to a receptor without activating it. An antagonist prevents other molecules, such as neurotransmitters or…

The combined effects of drugs can result in various interactions, of which an important type is antagonism. Antagonism is a mechanism where one drug…

Synergism is a useful mechanism where combining two or more drugs is more effective than each constituent used alone. Such combinations are also…

Some receptors remain unoccupied even when an agonist produces a maximal response. Such empty ones are called spare receptors. In presence of spare…

The receptor occupancy theory connects a drug's response to the number of occupied receptors. With higher drug concentrations, more receptors are…

The two-state receptor model explains a drug's interaction with receptors, such as G protein-coupled receptors and ligand-gated ion channels, to…

Tachyphylaxis is described as a rapid decrease in response to a drug after repeated or continuous administration of the same drug dose. It is a…

G-Protein-Coupled Receptors (GPCRs) are a large family of transmembrane receptors that play critical roles in normal cellular physiology and…

Label-free impedance-based assays are increasingly used to non-invasively study ligand-induced GPCR activation in cell culture experiments. The…

The concept of drug-combination therapy is becoming very important mainly with the drastic increase in resistance to drugs. The…