Receptors

Binding profile and mechanism: which targets are engaged, and whether the compound is an agonist, partial agonist, antagonist, allosteric modulator, reuptake inhibitor or releaser at each. Downstream matters as much as binding — biased signalling, receptor internalisation, tolerance, and an active metabolite with a profile of its own all belong here. So does what is not known: for most substances on this site the profile is partial, and for many it is a single screen against a panel that never included the target that matters.

Binding is not effect. Affinity says nothing on its own about potency in a person, about what a dose does, or about whether a drug reaches the brain at all, and a shared receptor does not make two drugs interchangeable. Where mechanism disagrees with where a substance sits on this tree, the filing follows the effect and this page carries the disagreement.