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PY366 Drug discovery > Bioassays in drug discovery > Flashcards

Bioassays in drug discovery Flashcards

1
Q

what are the main stages in drug development

A
  1. selection of disease target
  2. discovery of lead molecule by bioassay
  3. preclinical studies
  4. clinical studies
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2
Q

why are bioassays needed

A
  • to predict some type of therapeutic potential, either directly or by analogy, of test compounds
  • typically conducted to measure the effects of a substance on a living organism
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3
Q

define bioassay

A

any qualitative or quantitative analysis of a substance that uses a living system

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4
Q

give examples of bioassays

A
  • whole animals
  • isolated organs
  • lower organisms (bacteria)
  • cultured cells
  • isolated sub cellular systems (enzymes)
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5
Q

what are in vitro/ex vivo studies used for

A
  1. screening
  2. cell viability
  3. drug drug interaction studies
  4. metabolite identification/elucidation
  5. plasma protein binding
  6. genotoxicity
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6
Q

what is involved in screening assays

A
  • high throughput in vitro assay
  • specific assay
  • need to have a low cost and high specificity
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7
Q

what are screening assays used for

A

used in in vitro enzyme/receptor assays to test specificity in plate based format

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8
Q

give an example of assays to test for new drugs

A

cell growth for anti cancer medications

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9
Q

what needs to be considered in terms of pharmacodynamics of bioassays

A
  • does the drug affect the target at effective concentrations that can be reached clinically
  • does the drug modify the disease process in an animal model
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10
Q

how can drug effectiveness be tested

A
  1. test leading compounds
    - ex vivo on isolated tissues
    - in vivo in animal models of the disease to determine If it has the desired effect
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11
Q

how can pharmacokinetics be measured using bioassays

A

only very basic measurements can be made using bioassays
- full animal studies are required to get the full pharmacokinetic profile for ADME

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12
Q

What are drug drug interaction studies

A
  • using pooled human liver microsomes or other in vitro metabolism models
  • determine the effects of the new compound on metabolising enzyme activity and potential interactions/side effects
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13
Q

what is involved in metabolite identification/elucidation

A
  • using liver microsomes/cells
  • using LC-MS to identify possible metabolites
  • synthesise metabolites to test for toxicity and efficacy
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14
Q

what is involved in plasma protein binding study

A
  • using human and other species plasma
  • use equilibrium dialysis or ultrafiltration
  • determines the stability of drug in plasma
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15
Q

what toxicology studies can be conducted

A
  1. safety pharmacology
  2. cell viability
  3. cardiovascular toxicity
  4. genotoxicity
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16
Q

what toxicology studies can be conducted

A
  1. safety pharmacology
  2. cell viability
  3. cardiovascular toxicity
  4. genotoxicity
17
Q

what is safety pharmacology

A

studying the potential undesirable pharmacodynamic effects of a substance

18
Q

what is used in cell viability

A
  • MTT assays
  • LDH assays
  • apoptosis and necrosis measurements
19
Q

what is involved in testing cardiovascular toxicity

A
  • all drugs require hERG testing
  • if its ability to conduct electrical current across the cell membrane is inhibited or compromised, long QT syndrome may occur
20
Q

what is hERG

A

a potassium ion channel in the heart

21
Q

what is used in genetoxicity

A
  1. bacterial reverse mutation test- use bacteria which have mutations in genes involved in histidine synthesis
    - need histidine to grow
    - if they grow without histidine, indicates mutations induced by drug
  2. COMET assay- single cell gel electrophoresis to detect DNA damage
22
Q

what are ex vivo studies

A

test compounds on tissue taken from a living organism
- can be used to test effectiveness of a drug and identify potential side effects

23
Q

what are in vivo studies

A

testing which takes place in a living organism
- eg. animal models
- can be used to identify toxicity in key systems such as cardiovascular system, CNS, respiratory system

24
Q

what in vivo tests are conducted

A
  1. biochemical- blood levels of creatinine, ALT
  2. histopathology
  3. physiological observations- breathing, heart rate
  4. observation of behaviour when drug is administered

PY366 Drug discovery (15 decks)

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