raman govindarajan, md, phd. regional director medical and scientific affairs johnson and johnson...

Raman Govindarajan, MD, PhD.

Regional Director

Medical and Scientific Affairs

Johnson and Johnson Asia Pacific

Toxicology Fundamentals

A Day in Toxicology

• The Fundamentals of Toxicology

• Preclinical Safety Assessment of Cosmetics & Toiletries

How? Case Studies

Toxicology: Fundamentals

• What is Toxicology?

The traditional definition of toxicology:

" the science of toxin ”.

• What is Toxicology?

A more descriptive definition of toxicology:

"the study of the adverse effects of chemicals or physical agents on living organisms".

Which one of the following is a toxin?

1. Alcohol

2. Aspirin

3. Water

4. Table salt

Toxicity depends on the DOSE

“All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy.”

-- Paracelsus

• Toxicity depends on the dose– High oxygen level cause “oxygen intoxication”

• Toxicity depends on the dose– High oxygen level cause “oxygen intoxication”– Too much water (several gallons) can cause

osmotic imbalance and brain damage

osmotic imbalance and brain damage– 1 beer vs. a six pack of beer

osmotic imbalance and brain damage– 1 beer vs. a six pack of beer– 1 sleeping pill vs. a bottle of sleeping pills

osmotic imbalance and brain damage– 1 beer vs. a six pack of beer– 1 sleeping pill vs. a bottle of sleeping pills– 1 aspirin vs. a bottle of aspirins

What is LD 50 ?

1. Fifty Lead molecules

2. A famous singer in 1950’s

3. A Latin dance introduced in 1950’s

4. A means to measure toxicity

How is Toxicity measured by?

Toxicity is measured by LD50:

Lethal Dose that kills

50% of the population

Toxicity is measured by:

• LD50: Lethal Dose that kills 50% of the population

• Dosage measured in weight of toxin per body weight

Dose-response curves are used to derive dose estimates of chemical substances. A common dose estimate for acute

toxicity is the LD50 (Lethal Dose 50%).

Examples of LD50:

Chemical LD50 (ppm)

Nicotine 1

DDT 100

Table Salt 3000

Trichloroethylene 5000

What is ED 10 ?

1. The 10th version of ET movie

2. Brief for the 10th Edward in the family

3. The 10th Executive Director in a company

4. Indication of the effectiveness of a substance

Effective Doses (EDs) are used to indicate the effectiveness of a substance. Normally, effective dose refers to a beneficial effect (relief of pain). It might also stand for a harmful effect (paralysis). Thus the specific endpoint must be indicated.

Effective Dose

What does EC stands for?– 1. Title for a TV show starring a talking horse– 2. Effective concentration– 3. Exposure concentration – 4. New musical show in Broadway

• EC10

This is the commonly used abbreviation for the exposure concentration of a toxicant causing a defined effect on 10% of a test population

Absorption is the process whereby a substance moves from outside the body into the body.

Definition

What is Toxicokinetics?

Toxicokinetics is the study of "how a substance gets into the body and what happens to it in the body".Essentially, it is the study of “the kinetics of all toxic substances”.

Toxicity/Preclinical Safety Review

• Single Dose Study

• Multiple Dose Study: Subacute, Subchronic, Chronic

• Mutagenicity/Carcinogenicity Study

Acute toxicity results from a single exposure to a poisonous substance.

Route of administration:

Oral, IV, IP, Dermal, Subcutaneous

Acute toxicity results from a single exposure to a poisonous substance– Usually has an immediate life-threatening

effect

effect– Usually easily diagnosed

effect– Usually easily diagnosed– Most of the time there are antidotes that can

reduce the toxicity of the chemical

Multiple Dose Tests:

Subacute: days to 2 wks

Subchronic: 4 - 13 wks

Chronic: 6 - 12 months in rodents

7 - 10 years in non-rodents

Study design depending on the objective of the study

Chronic toxicity results from prolonged exposure to a poisonous substance over a long period of time

Chronic toxicity results from prolonged exposure to a poisonous substance over a long period of time– No immediate effect but could be life-

threatening in the long term

threatening in the long term– Usually hard to diagnose and treat

threatening in the long term– Usually hard to diagnose and treat– Hard to distinguish effects from other

influences

What is mutagenic?

1. Something to do with music

2. Something to do with DNA

3. Something to do with mutes

• Mutagenesis

The process whereby a substance damages

DNA and produces alterations in or loss

of genes or chromosomes.

Mutagenicity Tests– Ames Test

– Mammalian Chromosomal Aberration

– Micronucleus Test (in vivo)

What is carcinogenic ?

1. A place that makes cars

2. Something to do with gambling

3. Something that can cause tumors

4. A place that repairs cars

• Carcinogen A carcinogen is any substance which

causes cancer

Carcinogenicity Studies• Traditional 2-year Bioassay– different routes of administration, use rats and mice – two year duration, expensive, labor-intensive– interspecies extrapolation problem, especially mice

Carcinogenicity Studies• Traditional Testing– different routes of administration, use rats and mice

– two year duration, expensive, labor-intensive

– interspecies extrapolation problem, especially mice

• Transgenic Animal Testing – P53, Neonatal, TgAc, XPA, XPA/P53 and RasH2 models

– shorter testing period, less expensive, less labor-intensive

– have genes relevant to humans

– predictability? -- not enough data

What is a reproductive toxin?

Toxicology: Basic

Reproductive toxicity is defined as adverse effects on the male and female reproductive systems that result from exposure to chemical substances.

Which of the following causes reproductive toxicity?

1. Alcohol2. Vitamin A

3. Tobacco smoke (primary)

4. Aspirin

Special Toxicity Studies

• Eye Irritation • Skin Irritation • Contact Sensitization • Comedogenicity• Genital/Mucus Membrane Irritation

Irritation:

Any substance causing inflammation following immediate, prolonged, or repeated contact with skin or mucous membrane.

• The most common cause of Occupational Skin Disease is irritation of the skin from contact with substances at work.

Strong irritants (e.g. acids, alkaline or solvents) cause skin inflammation after a short period of skin contact.

Dermatitis from cement

Weak irritants (such as water, detergents, coolants) cause inflammation after repeated exposures over a longer time.

Dermal Irritation Tests

– Primary Irritation Test • Single Dose

– Cumulative Irritation Test• Multiple Dose

• In intracutaneous irritation tests using albino rabbits, the raised blebs caused by injecting extracts of test materials are either resolved without causing any visible changes or produce inflammation marked by redness and swelling in the 24 to 72 hours following injection.

Sensitization or hypersensitivity reactions usually occur as a result

of repeated or prolonged contact

with a substance that interacts

with the body's immune system.

Which of the following is considered

to be a sensitizer?

1. Latex Gloves

2. DNCB (1-chloro-2, 4-dinitrobenzene)

3. Kathon®CG

4. All of the above

After wearing natural latex gloves daily for several weeks or months, a person may develop a rash

Biomaterials and devices that cause sensitization reactions do so by means of their extractable chemical caused cell-mediated immunity.

Commonly Used Sensitization Tests

• Guinea Pig Maximization Test

(Magnuson-Kligman Test)

• Modified Buhler’s Test

• Local Lymph Node Assay

Positive response to DNCB in a guinea pig, seen in the maximization test

What does following compounds have in common?

1. Polycyclic aromatic hyrocarbons

2. Quinolones

3. Tetracyclines

4. PABA

Ingredients absorb in the solar spectrum (280 - 400 nm)

• Photomutagenicity • Phototoxicity• Photosensitization • Photocarcinogenicity

Studies to support Product Claims

• Ocular Irritation (Draize or TEP)

• Genital/Mucus Membrane Irritation

• Comedogenicity

• HET CAM – eye irritation test

What is comedone?

Comedone:

A follicle that has been plugged with a combination of hardened oil (sebaceous material) and dead skin cells.

Which of the following can causes a comedogenic reaction?

1. Cocoa Butter

2. Lanolin

3. Amydimethyl PABA

4. All of the above

1. Cocoa Butter - a skin softener and lubricator. It is considered comedogenic and may cause allergic reactions.

2. Lanolin - a sheep’s wool derivative, it is highly comedogenic.

3. Amyldimethyl PABA - causes skin irritation.

4. All of the above

• Skin Absorption Data

• Toxicokinetic and Pharmacokinetic Data

Other important information:

Photosensitization :Hypersensitivity to light.

An abnormally heightened response, especially of the skin, to sunlight or ultraviolet radiation, caused by certain disorders or chemicals and characterized by a toxic or allergic reaction

Safety Testing

• Knowledge of Toxicity is primarily obtained in 3 ways:– by studies using cells (in vitro)– by experimental studies using animals– by the study and observation of people during

normal use of a substance

Four basic steps in the risk assessment process:

Toxicology quiz

What is “toxicologist”?

1. A person who always kills my project

2. A person who is intoxicated

3. A person who can not make it to medical school

4. Our partner in R&D

Formulator and Toxicologist works together

faster time to market !

New Formulation

Toxicology Testing

New Formulation

Toxicology Testing To Market

New Formulation

Toxicology Testing To Market

raman govindarajan, md, phd. regional director medical and scientific affairs johnson and johnson...

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