Basic Drug Pharmacology

Question 1

What are the four main kinds of regulatory proteins commonly involved as primary drug targets?

Answer 1

• Receptors
• Enzymes
• Carrier molecules
• Ion channels

Question 1

What is a receptor?

Answer 1

A target molecule through which soluble physiological mediators produce their effect

Question 2

What are the main receptor classes?

Answer 2

A. Ligand-gated ion channels e.g. cholinergic nicotinic receptors
B. G protein-coupled receptors e.g. alpha and beta adrenoreceptors
C. Enzyme-linked receptors e.g. insulin receptors
D. Intracellular receptors e.g. steroid receptors

Question 3

What is an agonist?

Answer 3

A substance that interacts with a specific cellular constituent, the receptor, and elicits an observable biological response - it may be an endogenous or exogenous substance

Question 4

What is meant by a partial agonist?

Answer 4

Acts on the same receptor as agonists but regardless of its dose cannot produce the same maximal biological response as a full agonist.

Question 5

What is an inverse agonist “negative antagonist”?

Answer 5

Acts on the same receptor of the agonist yet produces an inverse effect

Question 6

What is meant by a spare receptor?

Answer 6

Receptors which exist in excess of those required to produce a full effect.

Question 7

What is meant by intrinsic activity?

Answer 7

A proportionality constant of the ability of the agonist to activate the receptor as compared to the maximally active compound in the series being studied

Question 8

What is an antagonist?

Answer 8

Inhibits the effect of an agonist but has no biological activity of its own.
Can compete for the same receptor site or act on the allosteric site

Question 9

What is a competitive antagonist?

Answer 9

• Binds to the same site as the agonist in a reversible manner

Question 10

What is a noncompetitive antagonist?

Answer 10

Binds to the same site as agonist irreversibly.

Question 11

What is an allosteric antagonist?

Answer 11

Antagonist and agonist bind to different site on same receptor

Question 12

What is a physiological antagonist?

Answer 12

Two drugs have opposite effects through differing mechanisms

Question 13

What is a heteroreceptor?

Answer 13

A receptor that regulates the synthesis and/or the release of chemical mediators other than its own ligand.

Question 14

What is an auto receptor?

Answer 14

A macromolecule typically found in the nerve ending that regulates the synthesis and/or release of its own ligand

Question 15

What is meant by receptor down-regulation?

Answer 15

A phenomenon whereby an agonist induces a decrease in the number of those receptors available for binding.

Question 16

What is meant by receptor up-regulation?

Answer 16

A phenomenon whereby an agonist induces an increase in the number of receptors available for binding.

Question 17

What is meant by affinity?

Answer 17

The ability of a drug to combine with a receptor;
It is proportional to the binding equilibrium constant KD;
A ligand of low affinity requires a higher conc to produce the same effect

Question 18

What is meant by efficacy?

Answer 18

A measure of the biochemical or physiological effect following the binding of a drug to its target;
It is a measure of the maximum effect the drug can produce

Question 19

What is meant by potency?

Answer 19

Refers to the dose of a drug required to produce a specific effect of given magnitude as compared to a standard reference;
Potency is dependant upon both affinity and efficacy

Question 20

What is a ligand?

Answer 20

Substance, molecules or compounds which bind with receptors present in the body;
They produce various effects and interfere with the flow of ions through channels called ligand gated channels

Question 21

Describe the action of agonists.

Answer 21

Drugs bind to receptors;
cause activation of receptors;
Have capacity to produce chain reactions in the receptors;
Which bring about the effects

Question 22

State the two properties of agonists.

Answer 22

• Affinity for receptor
• Capability to produce chain reactions in the cells having capability of intrinsic activity or efficacy

Question 23

What is meant by the actions of drugs?

Answer 23

The biochemical physiological mechanisms by which the chemical produces a response in living organisms

Question 24

What is meant by the effect of a drug?

Answer 24

The observable consequence of a drug action.