8 Flashcards
(19 cards)
a molecule (e.g. drug, hormone, antibody) that binds to a receptor
ligand
substances that are foreign to the body
xenobiotic
any biological molecule to which a drug binds and produces a measurable response
a receptor (or signal detector)
4 major receptor families
- ligand gated ion channels
- G protein-coupled receptors
- enzyme-linked receptor
- intracellular receptors
2 groups
- intracellular or extracellular
- receptors or channels
- (3 of the groups are receptors, 1 is an ion channel
a measure of the amount of drug necessary to produce an effect of a given magnitude
potency
the magnitude of response a drug causes when it interacts with a receptor
efficacy
maximum efficacy assumes that:
- all receptors are occupied by the drug
- no increase in response is observed if a higher concentration of drug is obtained
which is more clinically useful: efficacy or potency and why?
efficacy because a drug with greater efficacy is more therapeutically beneficial than is one that is more potent
how strongly a drug molecule binds to a binding site (the strength of the interaction)
affinity
the degree of a drug’s affinity for the receptor site
dissociation constant (Kd)
the higher the Kd value, the ___ the interaction and the ____ the affinity
- weaker the interaction
- lower the affinity
types of agonists
- full agonists
- partial agonists
- inverse agonists
types of antagonists
- competitive antagonists
- irreversible antagonists (non-competitive)
- allosteric antagonists (non-competitive)
when the antagonist and the agonist bind to the same receptor in a reversible manner (reduces potency)
competitive antagonists
how can you overcome competitive antagonists
increasing concentration of agonist relative to antagonist
what reduces the number of receptors available to the agonist by binding covalently to the active site of the receptor
irreversible (non-competitive) antagonists
can irreversible (non-competitive) antagonists be overcome and what do they reduce?
- they cannot be overcome by adding more agonist
- they reduce efficacy
what binds to a site other than the agonist-binding site and prevents the receptor from being activated by the agonist
allosteric (non-competitive) antagonists
