A drug that binds to a receptor and produces a biological response.

A drug that binds to a receptor but does not produce a response, blocking the action of agonists.

The ability of a drug to bind to a receptor.

The fraction of an administered drug dose that reaches the systemic circulation.

The ability of a drug to produce a desired therapeutic effect.

The emission of light by a substance that has absorbed light, used in various biological assays.

The maximal effect a drug can produce compared to a full agonist.

Proteins that allow ions to pass through a cell membrane, driven by electrochemical gradients.

The dissociation constant, indicating the affinity of a drug for a receptor.

The inhibition constant, representing the binding affinity of an inhibitor.

Vesicles derived from the endoplasmic reticulum, used in drug metabolism studies.

The primary binding site on a receptor for the endogenous ligand.