2.1 Pharmacodynamics

Question 1

What is a drug?

Answer 1

A chemical substances of known structure that produces a biological effect when administered to a living organism

Question 2

What problems might occur that means a particular drug might need to be used?

Answer 2

Exaggerated/Inadequate response

Over/under production of compounds

Bacterial or viral infection

Question 3

What effects can drugs have on the body?

Answer 3

Mimic - actions of substances produced in the body

Inhibit - actions of substances produced in the body to reduce an exaggerate response

Question 4

What are the 3 types of drugs?

Answer 4

Agonist - produced max. effects when binds to target

Partial agonist - sub-max. response

Antagonist - inhibits effects of an agonist

Question 5

Why are full and partial agonists needed?

Answer 5

Some drugs are less effective at switching on events inside a cell to result in a response - low efficacy

Question 6

What is a biased agonist?

Answer 6

Different agonist acting on the same receptor can show bias towards stimulation of 1 pathway/the generation of a particular response over another.

This may be why choose one drug over another.

Question 7

Describe agonist-receptor binding.

Answer 7

Agonist binds to target

Effect

Agonist dissociate rapidly but rapidly replaced by more agonist so effect maintained

repeated until significant agonist removed from environment so response stops

Question 8

Explain the interaction between antagonists and receptors.

Answer 8

Antagonist binds reversibly

strong covalent bonds dissociate v. slowly (effects are essentially irreversible)

antagonists from the same drug class may have different affinities.

Question 9

What are the 7 different types of antagonism?

Answer 9

Competitive reversible antagonist

Competitive irreversible antagonist

Non-competitive antagonist

Physiological antagonism

Pharmacokinetic antagonism

Chemical antagonism

Tachyphylaxis

Question 10

What is an inverse agonist?

Answer 10

Drugs that bind to receptors that elicit a response when no ligand is bound, hence reduce a response

Question 11

Define pharmacokinetic antagonism

Answer 11

A drug that effects the absorption, metabolism, elimination of another drug to reduce its action.

Question 12

Define chemical antagonism

Answer 12

A drug that interacts with another in solution, resulting in a reduction or loss of activity

Question 13

Define tachyphylaxis

Answer 13

(self antagonism / desensitisation)

a rapid loss of responsiveness to a drug when given continuously or repeatedly.

Question 14

Define tolerance

Answer 14

A gradual decrease in responsiveness to a drug

Question 15

Define resistance

Answer 15

The loss of effectiveness of antimicrobial or anti-cancer drugs

Question 16

Define affinity

Answer 16

How much of a response a drug produces

Question 17

Define potency

Answer 17

The concentration of a drug needed to produce a response

Question 18

Define ED50 and EC50

Answer 18

ED50 - the effective dose allowing 50% of their effect

EC50 - the effective conc. allowing 50% of their effect

Question 19

How are potency and efficacy measured?

Answer 19

Potency is compared by measuring ED50 or EC50

Efficacy is measured by response, irrespective of potency

Question 20

Define ID50 and IC50

Answer 20

The dose/conc. of an antagonist that causes 50% reduction in response

Question 21

Define therapeutic index

Answer 21

the range of doses at which a medication is effective without unacceptable adverse events