Unit 1: Drug Receptors

Question 1

Types of receptors

Answer 1

— orphan receptors
— regulatory proteins 
— enzymes
— transport proteins
— structural proteins

Question 2

E max

Answer 2

Efficacy

Maximum effect achievable by the drug

Question 3

EC 50

Answer 3

Potency

Dose or concentration at which the drug is half maximal

Question 4

ED 50

Answer 4

Median effective dose

Question 5

TD 50

Answer 5

Median toxic dose

Question 6

LD 50

Answer 6

Median lethal dose

Question 7

Full agonist

Answer 7

Drug can fully activate receptor system

Question 8

Partial agonist

Answer 8

Full activation is not possible even with full saturation

Question 9

Neutral antagonist

Answer 9

Does not cause an effect on its own; prevents binding by an agonist (e.g. naloxone and an opioid)

Question 10

Inverse agonist

Answer 10

Have higher affinity for R sub i than R sub a;

Decrease or abolish constitutive activity

Question 11

Biased agonism

Answer 11

Agonists in a group that activate the same receptors but have different downstream effects (biased effects)

(Mechanism not well understood)

Question 12

Competitive antagonists

Answer 12

E.G. naloxone

Drugs that bind to (or close to) agonist receptor site without activating effector system for that receptor (reversible binding)

Shifts dose-response curve to the right; maximal effect remains the same

Question 13

Irreversible antagonist

Answer 13

Dose-response curve gets decreased but not shifted, so maximum effect is less

Question 14

Physiologic antagonist

Answer 14

Bind to a different receptor molecule than the agonist does

Antagonize the physiologic response (e.g. glucagon and insulin are antagonists)

Question 15

Chemical antagonist

Answer 15

Interact directly with drug being antagonized to help remove it

e.g. medicines that chelate heavy metals

Question 16

Therapeutic effect

Answer 16

Range between median effective dose (ED 50) and median toxic dose (TD 50)

The wider the therapeutic index, the safer the drugs tends to be

Question 17

Therapeutic window

Answer 17

Doses that give effective treatment without toxicity

Range between minimum effective dose and minimum toxic dose

Question 18

Which tend to be more selective? Drugs that bind through weak bonds or strong bonds?

Answer 18

Drugs that bind through weak bonds tend to be more selective

Question 19

orphan receptors

Answer 19

Natural ligands unknown

Question 20

Receptors of regulatory proteins do what?

Answer 20

mediate actions of endogenous chemical signals

Question 21

What can binding of a drug do to an enzyme?

Answer 21

Inhibit it