2. Preclinical studies are conducted to define
pharmacological and toxicological effects not only
prior to initiation of human studies but throughout
clinical development.
Both in vitro and in vivo studies can contribute to
this characterization.
Definition
5. Whether a drug will move on to studies in humans
Designing phase I clinical trials.
Help to identify criteria for evaluating safety in
humans.
Why Preclinical Testing?
6. Detect overt toxicity
Identify, describe and characterize hazards
- reversible? - clinically monitor able?
Establish dose-response estimation of pharmacology
and toxic effects
Assess drug distribution to organ systems
Identify metabolic, kinetic and elimination pathways
Assess carcinogenicity, reproductive toxicity and
teratogenic potential
Why Preclinical Testing?
7. Medical uses/needs for substance
Commercial potential
Feasibility for mass production (manufacturing costs)
Major considerations while doing
Preclinical Studies
8. Short Term Animal Studies (Acute):
Determine pharmacological action and toxicity
Long Term Animal Studies (Chronic):
Look for potential side effects that may result from long
term use such as carcinogenicity
Look for reproductive effects
Types of Preclinical Testing
9. Data in two (2) Species is required
Why 2 Species?
Species differences in response
Rodent – almost always rat
Mouse has poorest clinical concordance
Non-rodent – dog, non-human primate
eg. Monkeys, apes
Species Selection
10. Safety Pharmacology
- functional assessment of major systems
General Toxicology
- target organs, “chronicity of the toxicity”
Developmental and Reproductive Toxicology
- fertility and reproductive performance
- embryo/fetal development
- neonatal development
Overview of Study Types
11. Genetic Toxicology
potential for cancer and heritable mutations
Carcinogenicity
6 months, 2+ species, same route of administration to be
used in humans)
Teratogenic Studies
Substance given to pregnant females and during lactation
(usually rats & rabbits)
Study Types Continu……
13. Pharmacodynamics
Pharmacokinetics
Single dose toxicity in two species
Repeated dose toxicity in two species, minimum 2 weeks.
Local tolerance
Teratogenicity study if fertile women are included in the
study.
Preclinical studies to be performed
before phase I clinical trials
14. All genotoxicity studies
Repeated dose toxicity. Duration depending on
duration of clinical study
Preclinical studies to be completed
before phase II clinical studies.
15. Fertility studies
Repeated dose toxicity
In parallel with phase II and phase III clinical studies,
other toxicity studies are completed
Preclinical documentation before phase
III clinical study
16. Steps involved with doing a Pre-
Clinical Trial:
File for approval as an Investigational New Drug (IND)
5
4
3
2
1
Establish Effective and Toxic Doses
Screen the Drug in the Assay
Develop a Bioassay
Indentify a Drug Target
17. Step One: Get an idea for a drug target.
Drugs target specific points in biochemical pathways
Biochemical pathways are series of chemical reactions occurring within a
cell. In each pathway, a principal chemical is modified by chemical
reactions. e.g.
A B C D E
Any step in the pathway, for example from A to B, or B to C, might be a
target for the right drug.
18. A Bioassay is a “live” system that can be used to measure
drug effect.
It may be a culture of cells or organs or a whole animal.
For example:
Zebra-fish embryos - you can see effect of drugs on
bone density, blood vessel growth and
many other systems of the zebra-fish.
Step Two: Develop a Bioassay
19. This is the actual test of the drug on
the chosen bioassay.
This will determine if the drug is SAFE and if
it is EFFECTIVE in the bioassay (BEFORE it is
ever tested on humans!)
Step Three: Screen the drug in the
Bioassay.
20. Establish what dosage amount of the drug is safe and
what dosage amount of the drug is toxic.
Most drugs have a toxic level or an amount at which the
drug will become harmful instead of helpful.
Step Four
21. Application is made to the
Food and Drug Administration (FDA)
as an Investigational New Drug (IND).
IND must show how the drug:
Is manufactured.
Appears (color, solubility, melting point,
particle size, moisture content).
Formulated (pills, liquid, etc. + inactive ingredients).
Will be analyzed for purity, concentration, stability.
Will be tested for safety (this will be the basis for allowing first
use in humans).
Step Five
22. Get idea for drug target
Develop a bioassay
Screen chemical compounds in assay
Establish effective and toxic amounts
File for approval as an Investigational New Drug (IND) (leads
to clinical trials)
Review: Steps to New Drug Discovery
Pre-Clinical Trials
23. Remington, the Science & Practice of Pharmacy, 21st
edition, Vol. 01, Pg. 965-972.
Pharmaceutical Dosage Forms and drug delivery
systems, 7th edition by Howard C. Ansel
http://www.fda.gov/ForPatients/Approvals/Drugs/uc
m405658.htm
Reference
The safety and other data from preclinical studies are crucial in determining whether a drug will move on to studies in humans
Guide researchers in designing phase I clinical trials. For example, preclinical studies with animals help determine the range of dosing of a test drug to be evaluated in a phase I clinical trial.
They also help to identify criteria for evaluating safety in humans, including signs and symptoms that should be monitored closely during early clinical trials.
Discovery Testing to ensure biological activity (in-vivo)
Chemical Synthesis & Scale up to ensure adequate quantities.
Formulation Development & Stability Testing.
Animal Safety Testing to ensure less toxicity of lead compound.
MOAs and SAR are determined in Discovery Testing.
Drug should be given to animals via same route as intended for human beings.
much of initial work is on assessing toxicity of substance
single doses of increasing strength
small groups of Ss, 2+ species
both sexes, young and older Ss
observed 1
-
7 days
different routes of administration
determine ED50, LD50, duration of effects
Ss are autopsied for cause of death
Once the toxic and lethal doses are dete
rmined in a species, subacute toxicity
is explored
at least 3 or more routes of administration
at least 3 different dose levels, 2+ species, small groups of Ss
observed 2 to 12 weeks
estimate what
the human dosages
will be
esp. note effects on liver, kidneys and NS
Chronic toxicity is studied, following the Ss for 3 to 24 months
Must wait at least until 6 months of animal testing has been completed before any testing of humans is allowed
also check for carcinogenic effects
(6 months, 2+ species, same route of
administration to be used in humans)
also check for
teratogenic effects
(substance given to pregnant females
and during lactation (usually rats & rabbits)