Intro Phramacodynamics

Question 1

Basic types of drug action can be broadly classified in to:

Answer 1

Stimulation: selective enhancement of the level of activity of specialized cells

Depression: Selective diminution of the activity of specialized cells

•Irritation; nonselective often noxious effect to less specialized cells(mild irritation with bitters)

•Replacement: use of natural hormones or congeners in deficiency states

•Cytotoxic action: selective cytotoxic action for

Question 2

Drug-receptor interactions can be described in two forms:

Answer 2

Agonists: drugs that can bind and activate the receptor by causing conformational change in the receptor (possess affinity and intrinsic activity)
•Antagonists: drugs that bind to receptors but do not activate the receptor (interfere with the ability of an agonist to activate the receptor by preventing its binding)

Question 3

Types of agonists

Answer 3

Full agonists

Partial agonists

Inverse agonists - inactivates active receptors

Question 4

Type of antagonism

Answer 4

1)Pharmacological(receptor) antagonism(act on same receptor)

2)Physiological Ant.(different receptors involved) -histamine and adrenaline

3)Chemical Ant.(chemical reaction)

4)Physical Ant. (physical adsorption)

Question 5

Pharmacological antagonist types

Answer 5

Competitive

Non competitive

Question 6

Competitive pharmacological antagonist

Answer 6

Binds to the same site as the agonist reversibly ( higher conc. of agonist displaces it)

Maximum effect is reached

Question 7

Non competitive antagonist

Answer 7

Non-competitive antagonist: binds to a different allosteric site making the receptor unable to combine with the agonist properly

Question 8

Competitive antagonism properties

Answer 8

Non-equilibrium(competitive) antagonism:
•Chemically similar to agonist
•Binds to the same site with covalent bond
•Agonist unable to reduce receptor occupancy of the antagonist
•Termed as irreversible or non-equilibrium antagonism
•Log DRC is shifted to the right and the maximal response is lowered(if spare receptors are few)

Question 9

Non competitive antagonist characteristics

Answer 9

•It is chemically unrelated to the agonist
•Emax is lowered
•Log dose-response curve shifts to the right but not parallel to D-R curve of the agonist alone
•Even high conc. of agonist is unable to reverse the block by antagonist

Question 10

Two theories of receptor mediated action:

Answer 10

1 receptor occupation theory

2 rate theory

Question 11

potency

Answer 11

amount of dose needed to elicit a given response
ED50

Question 12

efficacy

Answer 12

maximum response produced by a drug
EDmax

Question 13

Two types of dose-response-relationships:

Answer 13

Graded dose response relationship(GDRR)

Quantal dose response relationship(QDRR)

Question 14

GDRR

Answer 14

GDRR used for characterization of the effect of a drug on a subject
It is characterized by stating the EC50 (conc. of a drug that produces 50% of the maximal effect)

Answer 15

QDRR are characterized by stating the median effective dose(ED50 ): the dose at which 50% of individuals exhibit the specified quantal effect
Median toxic dose(TD50 ): the dose required to produce a particular toxicity in 50% of animals
Median lethal dose(LD50 )- the dose that produces death in 50% of animals

Question 16

Receptors:

Answer 16

Receptors:
Determine the quantitative relations between the dose and pharmacologic effects
Are responsible for selectivity of drug action
Mediate the actions of pharmacologic agonists and antagonists