Drug Receptors 1

When drugs engage with drug receptors?

they alter the biochemical or biophysical activity of the receptor

What determines the concentration of drug needed to form significant numbers of drug receptor complexes

affinity of a drug for a given receptor

The total number of receptors may limit what

the maximal effect a drug may produce

What are receptors responsible for?

the selectivity of drug action

What will determine the affinity of a drug for a given receptor?

the molecular size, shape and charge of a drug

Nearly all clinically relevant drugs, most receptors are

proteins

Regulatory proteins

macromolecules that mediate the actions of endogenous chemical signals neurotransmitters, autacoids, hormones

The three most common types of drug receptors are

enzymes, transport proteins, and structural proteins

Enzymes

biological catalysts for specific biochemical reactions

Example of an enzyme

EGFR

Transport proteins

are membrane bound receptors that facilitate the movement of molecules across cell membranes

Example of transport proteins

SGLT2 (brings glucose and sodium from urine into blood)

Structural protein

are the components of a cell that provide structural support and integrity

Example of structural proteins

tubulin

Bmax

represents the maximum number of receptor sites bound by drug at exceedingly high agonists concentration

Kd

represents the [drug] that achieves half maximal occupancy and can be also be referred to as the binding affinity

Coupling

the transduction process linking receptor occupancy to response and is determined by the following downstream biochemical events that transduce the occupancy into a cellular response

The receptors not bound by drug maximal response are considered to be

spare

the smaller the Kd the

higher the affinity for the receptor

Antagonist

dampens or inhibits some physiological response when bound to a receptor

Ki

potency of an inhibitory drug (antagonist) relative to a given agonist-receptor interaction

The lower the Ki the

greater the potency