Assessment 2 Multiple Choice

Front 1

Define EC50:

Back 1

The molar concentration of an agonist that produces 50% of the maximal possible effect of that agonist.

Front 2

Define Potency:

Back 2

Expresses the activity of a drug, in terms of the concentration or amount needed to produce a defined effect.

Front 3

What is a Hill Plot:

Back 3

Used to determine the number of binding sites on a particular molecule.

Front 4

Define an agonist:

Back 4

A ligand that binds to a receptor and alters the receptor state resulting in a biological response, e.g. contraction, relaxation, secretion, etc.

Front 5

Define a Schild plot:

Back 5

A plot of log (dr-1) against log antagonist concentration, where r is the concentration ratio.

Front 6

Define Efficacy:

Back 6

The ability of a drug to produce a desired therapeutic effect. Reflects the extent to which different agonists produce varying response, even when occupying the same proportion of receptors.

Front 7

Define pA2:

Back 7

The negative logarithm to base 10 of the molar concentration of an antagonist that makes it necessary to double the concentration of the agonist needed to elicit the original response obtained in the absence of antagonist.

Front 8

Spare Receptors:

Back 8

Exists when a full agonist can cause a maximum response when occupying only a fraction of the total receptor population.

Front 9

Scatchard Plot:

Back 9

Used to determine the Bmax and Kd of ligand binding.

Front 10

Define Antagonist:

Back 10

A drug that reduces the action of another drug agonist. May act at the same target site receptor as the agonist.

Front 11

Define non-competitive antagonist

Back 11

Binds covalently or with very high affinity to the agonist site preventing agonists from activating the receptor.

Front 12

The agonist log concentration-effect curve is shifted to the right when this occurs.

Back 12

Competitive antagonism

Front 13

Therapeutic Index

Back 13

The ratio between the toxic dose and therapeutic dose of a drug.

Front 14

Define a Comet Assay:

Back 14

A sensitive in vivo test for assessing DNA breakage.

The DNA fragments from lysed cells are separated by gel electrophoresis and visualised using fluorescence microscopy following staining. Increased fluorescence intensity indicates increased frequency of DNA breaks.

Front 15

Thymidine kinase mouse lymphoma cell assay

Back 15

Similar to the Ames assay in that the detection system examines the mutation of a particular gene to a non-functional form

Front 16

Define Ames Assay:

Back 16

Mutagenicity is assessed via the growth of mutant strains of S. typhimurium in the absence of supplemental amino acids (Histidine)

Front 17

The mutagenic potential of these test compounds can only be assessed in assays containing liver enzyme systems.

Back 17

Promutagens

Front 18

This assay uses a gene involved in regulating DNA repair, mitosis delay and apoptosis as a biomarker for genomic stress.

Back 18

GADD45a-GFP assay

Front 19

Define a Chromosomal aberration assay:

Back 19

Mammalian cell cultures are incubated with the test compound, with and without metabolic activation. Cells are arrested in metaphase and examined by microscopy.

Front 20

Define MCASE:

Back 20

Applies knowledge of structure-activity relationships to the prediction of toxicity.

Front 21

What is the aim of the International Committee on Harmonisation (ICH)?

Back 21

The aim of this organisation is to speed up the development of new medicines by reducing duplication of testing whilst maintaining safety, quality and efficacy.

Front 22

Aneugenesis

Back 22

Interference of chromosome segregation in mitosis causing a change in chromosome number.

Front 23

Define Clastogenesis:

Back 23

The breakage of chromosomes

Front 24

Define LD50:

Back 24

The estimated dose required to kill 50% of a group of experimental animals.

Front 25

Micronucleus Assay:

Back 25

Can be used in both in vitro and in vivo genotoxicity testing to look at fragments of damaged chromosomes.