chapter 12. target disease priority for the pharmaceutical industry: can the profits from marketing...

Chapter 12

Target diseaseTarget diseasePriority for the Pharmaceutical Industry:Priority for the Pharmaceutical Industry:Can the profits from marketing a new drug outweigh the cost of developing and testing that drug?

Questions to be addressed:Questions to be addressed:Is the disease widespread?

(e.g. cardiovascular disease, ulcers, malaria)Does the disease affect the first world? (e.g. cardiovascular disease, ulcers)Are there drugs already on the market?If so, what are their advantages and disadvantages (e.g. side effects)Can one identify a market advantage for a new therapy?

Drug targetsDrug targetsA) Lipids

Cell membrane lipids

B) Proteins ReceptorsEnzymesCarrier proteins

Structural proteins (tubulin)

C) Nucleic acids

DNARNA

D) CarbohydratesCell surface carbohydratesAntigens and recognition molecules

Between species: • Antibacterial, antifungal and antiviral agents• Identify targets which are unique to the invading pathogen• Identify targets which are shared but which are significantly different in structure

Within the body:• Selectivity between different enzymes, receptors etc.• Selectivity between receptor types and subtypes• Selectivity between isozymes• Organ and tissue selectivity

Bioassays (test systems)Bioassays (test systems)

• Tests are required in order to find lead compounds and for drug optimisation• Need to be quick, easy and relevant• Tests can be in vivo or in vitro

• A combination of tests is often used in research programs

• Carried out on live animals or humans• Measure an observed physiological effect• Measure a drug’s ability to interact with its target and its ability to reach that target• Can identify possible side effects• Rationalization may be difficult due to the number of factors involved• Transgenic animals - genetically modified animals • Drug potency - concentration of drug required to produce 50%

of the maximum possible effect• Therapeutic ratio/index -

compares the dose level of a drug required to produce a desired effect in 50% of the test sample (ED50) versus the dose level that is lethal to 50% of the sample (LD50)

In vivo TestsIn vivo Tests

• Tests not carried out on animals/humansTarget molecules (e.g. isolated enzymes or receptors)

Cells (e.g. cloned cells)Tissues (e.g. muscle tissue)

Organs Micro-organisms (for antibacterial agents)

• More suitable for routine testing• Measure the interaction of a drug with the target but not the ability of the drug to reach the target• Results are easier to rationalize - less factors involved• Does not demonstrate a physiological or clinical effect• Does not identify possible side effects• Does not identify effective prodrugs

In vitro testsIn vitro tests

•High Throughput Screening•NMR•Enzyme Inhibition tests

•Identify competitive or non competitive inhibition• Strength of inhibition measured as IC50

• IC50 = concentration of inhibitor required to reduce enzyme activity by 50%

•Receptor tests•Not easy to isolate membrane bound receptors• Carried out on whole cells, tissue cultures, or isolated organs• Affinity - strength with which compounds bind to a receptor• Efficacy - measure of maximum biochemical effect resulting from binding of a compound to a receptor. • Potency - concentration of an agonist required to produce 50% of the maximum possible effect.

Testing drugsTesting drugs

The lead compoundThe lead compound

• A compound demonstrating a property likely to be therapeutically useful

• The level of activity and target selectivity are not crucial

• Used as the starting point for drug design and development

• Found by design (molecular modelling or NMR) or by screening compounds (natural or synthetic)

• Need to identify a suitable test in order to find a lead compound

• Active principle - a compound that is isolated from a natural extract and which is principally responsible for the extract’s pharmacological activity. Often used as a lead compound.

A) The natural world

B) The synthetic world

C) The virtual world

Plantlife (flowers, trees, bushes)Micro-organisms (bacteria, fungi)Animal life (frogs, snakes, scorpions)Biochemicals (Neurotransmitters, hormones)Marine chemistry (corals, bacteria, fish etc)

Chemical synthesis (traditional)Combinatorial synthesis

Computer aided drug design

The lead compoundThe lead compound

A) Isolation and purificationA) Isolation and purificationsolvent-solvent extractionchromatographycrystallizationdistillation

B) Structure determinationB) Structure determinationelemental analysismolecular weightmass spectrometryIR spectroscopyUV spectroscopyNMR (1H, 13C, 2D) spectroscopy

X-ray crystallography

Identification of the lead compoundIdentification of the lead compound

PlantsPlants

Lead compounds from the natural worldLead compounds from the natural world

Poppy capsulePoppy capsule

MorphineMorphine


• OPIUMOPIUM - Morphine- Morphine

• CINCHONA BARKCINCHONA BARK - Quinine- Quinine

• YEW TREEYEW TREE - Taxol- Taxol


Willow tree - salicylic acidWillow tree - salicylic acid

Coca bush - cocaineCoca bush - cocaine

AspirinAspirin

ProcaineProcaine

OH

O OHAceticanhydride O

O OH

CH3

O

N

Me

O

H

H

CO2Me

C

O

O

C

O

N

NH2

CH3

CH3


The beatons of pennycross


CURE for EPILEPSYCURE for EPILEPSY

Heat a cauldron of wateruntil warm to the touch

Add a liberal sprinklingof juicy spidersProduce one pedigree dogFlavour with essenceof dog turdSimmer for 20 minutesthen enjoy

THE BEATONS OF PENNYCROSSTHE BEATONS OF PENNYCROSS

Herbal remedies of oldHerbal remedies of old

Majority may have worked through a placebo effect


Rain forestsRain forests


Coral and marine chemistryCoral and marine chemistry

CURACIN

OMe

CH3

NS

H H

CH3


Micro-organismsMicro-organisms


• Penicillin• Cephalosporins• Tetracyclines• Streptomycin• Chloramphenicol

N

S CH3

CH3O

HH

CO2H

HN

R

O

N

S

OAc

CO2HO

HN H HC

O

R

OOHOOH

Cl

OH

NMe2

O

HO

NH2

Me H

OH

O2NCH2OH

HO

HN

H

H

CO CHCl2

H2N C

HN

NH

O

HN C

NH

NH2

O

OO

H

OHH HO

HH

OHH

H

CHO

OH

H

Me

CH2OH

HHO

H

OH

H

H

MeHN

H

H

Lead compounds from the natural worldLead compounds from the natural worldMicro-organismsMicro-organisms

Venoms and toxinsVenoms and toxins

Captopril(anti-hypertensive)

H2N CH C

CH2

O

CH2

C

OH

O

NH

CHC

CH2

O

HN

N

C

O

NH

CHC

CH2

O

CH2

CH2

NH

C

NH2

NH

N

C

O

NH

CHC

CH2

O

CH2

C

NH2

O

HN CHC

CH

O

CH3

CH2

CH3

N

C

O

N

C OH

O

CH3

C

O

N

C OH

O

HS

Teprotide


NCH3

MeO

HO

OH

CH3

NH3C

OMe

O

H3C

HO

H

Tubocurarine(from curare)

Lead compounds from the natural worldLead compounds from the natural worldVenoms and toxinsVenoms and toxins

NCH3

MeO

HO

OH

CH3

NH3C

OMe

O

H3C

HO

H

NO

C

O

(CH2)5 OC

OMeO

MeO

OMe

OMe

N

OMe

OMe

OMe

MeO

CH3 H

Atracurium(Neuromuscular blocker)

Tubocurarine(from curare)



Endogenous compoundsEndogenous compounds

Natural ligands for receptors

HO

HO

ADRENALINE

HN

Me

OH

HO

HO

OH

SALBUTAMOL

HN

AgonistAgonist

NH2

NH

HO

5-HYDROXYTRYPTAMINE

NMe2

NH

SUMATRIPTAN

SMeHN

O OAgonistAgonist


O NH

OH

PROPRANOLOL

AntagonistAntagonistHO

HO

ADRENALINE

HN

Me

OH

HNN

Me

S

HN NHMe

CN

CIMETIDINE

HNN

NH2

HISTAMINE AntagonistAntagonist

Lead compounds from the natural worldLead compounds from the natural worldEndogenous compoundsEndogenous compounds

Natural ligands for receptors

Endogenous compoundsEndogenous compounds

Natural substrates for enzymes

EnkephalinsEnkephalins Enkephalinase inhibitorsEnkephalinase inhibitors

PeptidesPeptides Protease inhibitorsProtease inhibitors

H2NN

HO

CO2HH

L-Phe-L-Pro

HN

NH

N

N

OCONH2

HO

H

H

OHH

H

H NH

O

SAQUINAVIR


Lead compounds from the synthetic worldLead compounds from the synthetic world

SYNTHETIC COMPOUNDSSYNTHETIC COMPOUNDSSYNTHETIC COMPOUNDS

H2N S NH2

O

NN

NH2

O

PRONTOSILPRONTOSIL


S NH2

O

H2N

O

SULFANILAMIDESULFANILAMIDE


TNT

ONO2

ONO2

ONO2


Rubber industryRubber industry

N SC

CS

S

H3C

H3C

N

S

CH3

CH3

Antabuse


Organic synthesisOrganic synthesis

4.4 Lead compounds from the synthetic world4.4 Lead compounds from the synthetic world

Automated synthetic machines

Combinatorial synthesisCombinatorial synthesis4.4 Lead compounds from the synthetic world4.4 Lead compounds from the synthetic world

RESINBEAD

AMINO ACID

AMINO ACIDS

XX

PEPTIDE

Combinatorial synthesis - peptide synthesisCombinatorial synthesis - peptide synthesis4.4 Lead compounds from the synthetic world4.4 Lead compounds from the synthetic world

NN NNY

OOCHR1R2

RESINBEAD

Combinatorial synthesis - heterocyclic synthesisCombinatorial synthesis - heterocyclic synthesis4.4 Lead compounds from the synthetic world4.4 Lead compounds from the synthetic world

RESINBEAD

NN NN

OO

R2R3

H


NN NN

OO

EtOO

OO

R2R3

R4R5

RESINBEAD


NN NN

NN

HNN

OO

R2R3

R4R5

RESINBEAD


NN NNY

NN

OO

R2R3

R4R5HHNN

RESINBEAD


The PastThe Past

Lead CompoundLead Compound

TargetsTargets

TargetsTargets

Lead compoundsLead compounds

The Present and FutureThe Present and Future

4.5 Lead compounds 4.5 Lead compounds - impact of the human genome project- impact of the human genome project

Lead compounds Lead compounds - impact of the human genome project- impact of the human genome project

4.6 Lead compounds - 4.6 Lead compounds - de novode novo design design


X-RAY CRYSTALLOGRAPHYX-RAY CRYSTALLOGRAPHY

PROTEIN STRUCTURE


Receptor


Scaffold

CO2

-HO

IONICIONICBONDBOND H-BONDH-BOND

VDWVDWBONDBOND

ScaffoldScaffoldScaffold

ScaffoldH3N+

O

CH3

NNHHNN

OO

SSOO

OO

NNHH

NN

NN NN

HH22NN

SSOO

OO

OO

NN

Thymidylate kinase inhibitorsThymidylate kinase inhibitors

Anticancer agent

Lead compoundLead compound

OptimisationOptimisation


4.7 Design of lead compounds using NMR spectroscopy4.7 Design of lead compounds using NMR spectroscopy

NMR spectroscopyNMR spectroscopy

Binding Site

ProteinProtein


ProteinProtein

No observable biological effect


1313C NMRC NMR

CCCC

CHCHCHCH

CHCH

CHCH22

CHCH22

CHCH33

CHCH33


CHCH22

CHCH33

1313C NMRC NMR

CCCC

CHCHCHCH

CHCH

CHCH22

CHCH33


ProteinProtein

Optimise Optimise epitopeepitope


ProteinProtein




ProteinProtein



LinkLink


LEAD COMPOUNDLEAD COMPOUND


HN

HO

OOH

NO

O

OMeOMe

MeO

O

O

Me

Design of a lead compound as an immunosuppressantDesign of a lead compound as an immunosuppressant

Epitope AEpitope A

Epitope BEpitope B


HN

HO

OOH

NO

O

OMeOMe

MeO

O

O

Me

Design of a lead compound as an immunosuppressantDesign of a lead compound as an immunosuppressant

Lead compoundLead compound


chapter 12. target disease priority for the pharmaceutical industry: can the profits from marketing...

Documents

receptor tests

drug targets

tissue selectivity slide

new drug

drug optimisation

relevant tests

combination of tests

target disease priority