Introduction

PHT 435

Cosmetics

Definition: A preparation designed to beautify and

improve the complexion, skin and hair. OrSubstances used to enhance appearance or

odor of the human body.

FDA define cosmetics as: Preparations or substances intended to be

applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance without affecting the body’s structure or functions.

So cosmetic substances are:1. All substances used for the maintenance of

body hygiene such as soaps, shampoos, tooth past.

2. Maintaining and protection cosmetics e.g. creams and lotions.

3. Decorative cosmetics e.g. makeup , lipstick.4. Hair coloring ,removal and perming.5. Deodorants antiperspirants , sunscreen

mouth preparations.

Medicines restricted to doctor’s prescription must not be present in the production of cosmetics.

Also it is essential that the name and address of the manufacturer of the cosmetic preparations be provided to guarantees consistent inspection and control for adherence to regulations.

History

The appearance of skin care formulation dates to around 3000 B.C.E. in ancient Egypt.

Most concoctions wereprepared from naturalmaterials.Nefertiti bust with eye liner applied ~1,320 BC (~3,300 years ago)

One naturally occurring material used by the ancients was red ochre, or iron oxide. Itwas found in lip tints and rouge preparations.

Skin

SKINE

1. Skin is area of application for cosmetics and toiletries.

2. Skin is the largest organ of the body and performs many functions important to life.

3. Average surface area of adult skin is 1.5-2 m2.

4. It has protective function as an interface between us and our environment.

5. It’s involved in various metabolic, storage, and regulatory tasks.

6. Thermoregulation: it maintaining the proper temperature for the body to function well.

7. It gathers sensory information from the environment, and plays an active role in the immune system protecting us from disease.

Skin consists of three layers:Epidermis, dermis, and subcutaneous tissue.

EpidermisThe epidermis is the outer layer of skin.

The thickness of the epidermis varies in different types of skin. It is the thinnest on the eyelids at .05 mm and the thickest on the palms and soles at 1.5 mm.

The epidermis contains 5 layers. From bottom to top the layers are named:Stratum basal.Stratum spinosum.Stratum granulosum.Stratum licidum.Stratum corneum.

The bottom layer, the stratum basal, has cells that are shaped like columns. In this layer the cells divide and push already formed cells into higher layers. As the cells move into the higher layers, they flatten and eventually die.

The top layer of the epidermis, the stratum corneum, is made of dead, flat skin cells that shed about every 2 weeks.

Functions of the stratum corneum

Protective.Physical and chemical barrier. Retards water loss from underlying

tissues.Minimizing UV light penetration.Limit entrance of microorganism and toxic

substances.Abraded continuously.

Its regeneration is provided by rapid cell division in the basal cell layer of the epidermis.

An acidic film ( pH 4.5 – 5.5 )made up of emulsified lipid cover surface of the stratum corneum.

Composition of surface oil:Triglyceride Wax esterFatty acids DiglycerideCholesterol and ester

Dermis The dermis also varies in thickness depending

on the location of the skin. It is 0.3 mm on the eyelid and 3.0 mm on the back.

The dermis is composed of three types of tissue

that are present throughout - not in layers.

The types of tissue are:1. Collagen.2. Elastic tissue.3. Reticular fibers.

Subcutaneous Tissue

The subcutaneous tissue is a layer of fat and connective tissue that houses larger blood vessels and nerves.

This layer is important in the regulation of temperature of the skin itself and the body.

The size of this layer varies throughout the body and from person to person.

The skin is a complicated structure with many functions. If any of the structures in the skin are not working properly, a rash or abnormal sensation is the result.

Skin appendages

Skin appendages are formed from the epidermis but reside in the dermis. 1. Sebaceous glands produce an oily

product (sebum), usually connected by a duct into a hair follicle. Sebum keeps the skin and hair soft.

2. A hair is primarily dead keratinized cells and is produced by the hair bulb.

3. Nails are hornlike derivatives of the epidermis. Like hair, nails are primarily dead keratinized cells. 4. Sweat glands, under the control of the nervous system, produce sweat, which is connected by ducts to the epithelial surface. These glands are part of the body's heat-regulating apparatus.

Cosmetic chemistry

Emulsions

The majority of creams and lotions are emulsions.

An emulsion can be defined simply as two immiscible fluids in which one liquid is dispersed as fine droplets in the other.

The non-dispersed liquid or external suspending phase is called the continuous phase.

Surfactants

Most emulsifiers can be considered surfactants or surface-active agents.

These materials are able to reduce the surface tension of water. What makes an emulsifier surface active is related to its HLB, or hydrophile-lipophile balance.

HLB is determined by the size of the hydrophilic (water-loving or polar) portion of a molecule as compared to the size of the lipophilic (oil-loving or nonpolar) portion.

The HLB system was created to rank the relative polarity of materials. The most polar, water soluble, materials are at the top of the twenty-point scale with more non-polar, oil soluble, materials closer to zero.

Examples:– The HLB of sodium caseinate is assigned a value of

around fourteen because of it's high solubility in water.

– Lecithin, being poorly soluble in water, has an HLB value of about six.

Skin-care emulsifiers can be divided into two groups based on ionic charge.

emulsifier

Ionic

nonionic

Ionic emulsifiers can be further classified by type of charge:1. Anionics are negatively charged when solvated as

in sodium stearate or soap.2. Positively charged emulsifiers are called cationic.

Quarternium24's emulsifying unit dissociates into the positively charged ammonium group.

3. Amphoterics are compounds that express both negative and positive charges.

Nonionic emulsifiers are often used in skin-care emulsion for their safety and low reactivity.

They are generally classified by chemical similarity.

Glycerin, commonly added to cosmetic emulsions for its humectant properties, is the backbone of a class of emulsifiers called Glyceryl esters .

Glyceryl mono- and diesters are very effective emulsifiers because they contain both polar hydroxyl (OH) groups as well as non-polar fatty acids.

If all three of Glycerin's hydroxyl groups are reacted, the resulting triester will have little emulsifying capability.

Stearic acid is called C18 fatty acid.

The fatty acids, present in fats and oils, are classified according to their carbon-chain lengths.

In beauty treatments stearate-based emulsifiers are particularly useful.

Fatty acids are key components of many cosmetic emulsifiers due their miscibility in a variety of natural and synthetic oils.

Esters polyethylene glycol or ethylene glycol are called PEG esters.

A polyethylene glycol (PEG) ester's solubility is determined by the number of PEG molecules reacted per molecule of acid.

PEG 6 oleate for instance has six molecules of PEG reacted with one molecule of oleic acid.

As the number of polar, PEG molecules per acid molecule increases the water solubility/HLB is increased.

PEG 8 oleate is more soluble than PEG 6 oleate.

The cosmetic chemist will often use blends of glyceryl esters and a PEG ester with high and low HLB values to determine the required polarity to emulsify various fats and oils.

Examples of emulsifiersExamples Emulsifiers Type

Soap, sodium laurylsulphat, dioctyl sodium sulphosuccinate , sodium oleate and stearate

Anionics

Cetyl tri methyl ammonium bromides , primary, secondary and tertiary amine salts

Cationics

Oil soluble: as glyceryl mono stearat and oleat ,spans.

Water soluble: as tween and polyoxy ethylen fatty acid ester.

Non ionics

How does one choose the proper emulsifier or emulsification system?

HLB system is a useful aids when considering non ionic surfactants:

Applications HLB

W/O emulsion 3-6

wetting 7-9

O/W 9-14

Solubilizing agent 10-18

Emollients

The majority of emollients used in personal care and beauty items are lipids.

Animal fat is composed primarily of stearic and palmitic acids with carbon chains lengths of 18 and 16 respectively.

Many of the major cosmetic companies are moving away from animal-based materials to renewable vegetable-based materials like Coconut oil and palm kernel oil

Some of the key characteristics required in good

emollients are good spreading properties, low toxicity/skin irritation and good oxidative stability.

Fats and oils are considered saturated if they do not have double bonds.

Oleic acid, a major constituent of olive oil has poor oxidative stability due to the presence of its double bond

Unsaturated oils like olive oil have double bonds that can react with oxygen, especially when heated. The oxidation process can produce off colors and odors in lipids causing them to go rancid and unusable.

Petroleum-based emollients such as petroleum jelly and mineral oil are found in many formulations because they do not contain double bonds or reactive functional groups.

Silicone oils such as cyclomethicone, dimethicone are often added to increase slip and emolliency.

Oils that contain high levels of essential fatty acids are prized for their ability to replenish lipids (oils) that are found naturally within the skin layers.

fatty alcohols are useful as emollients and emulsion stabilizers.

Esters of fatty alcohols and fatty acids make excellent emollients because of their low reactivity and good stability.

Lanolin, derived from sheep's wool, is often called wool grease.

Lanolin has been used for centuries due to it's unique composition of complex sterols, fatty alcohols, and fatty acids.

Moisturizers

The main distinction between moisturizers and emollients is their solubility in water.

Moisturizers are generally polar materials that are hygroscopic in nature; they hold onto water.

An important tool to assess the efficiency of moisturizers is the high scope. It measures transepidermal water loss (TEWL).

After a moisturizer is applied to the skin, the moisture level is recorded. After several minutes the moisture level will be reduced due to the natural tendency of the skin to release moisture over time.

Ingredients that can maintain a high level of moisture in the upper layers of the skin for several hours can reduce the rate at which water is lost.

Glycerin is a very cost-effective ingredient used to help reduce TEWL.

Sorbitol, sucrose, glucose, and other sugars are also commonly used to hydrate the skin.

Aloe, which contains a mixture of polysaccharides, carbohydrates, and minerals, is an excellent moisturizer.

Waxes

Waxes are composed primarily of long-chain esters that are solid at room temperature.

Some common waxes used in cosmetics are beeswax, candelilla, carnauba, polyethylene, and paraffin.

The melting points of waxes vary widely depending on their unique composition and chain lengths.

Commonly used in lip balms and sticks.

waxes function as structuring agents, giving the stick enough rigidity to stand up on its own, as well as barrier properties.

By combining waxes with different properties such as high shine, flexibility, and brittleness, optimal cosmetic performance can be achieved.

Often waxes are combined with compatible oils to achieve the desired softness.

Waxes are particularly useful in hand creams and mascara emulsions for their thickening and waterproofing properties.

Thickeners

By incorporating enough wax into a thin lotion, a thick cream can be formed.

Many thickeners are polymers.

Cellulose swells in hot water creating a gel network.

Carbopol, a polyacrylic acid, swells when neutralized.

Bentone clays swell when their structure, resembling a stack of cards, is opened up through mechanical shear.

Carrageenan, pectin, and locust bean gum are all examples of cosmetic thickeners that are also used in some of our favorite foods such as jellies, salad dressings, and pie fillings.

Active Ingredients

Materials that work physiologically within the skin or aid in protecting the skin.

The term "cosmeceuticals refers to a product that is in-between a cosmetic and a drug.

Many cosmetic products can be shown to penetrate the dermal layers of the skin to exact a physiological change.

Fruit acids are an example of an active material. Also called alpha hydroxyacids (AHAs), they have the ability to penetrate the skin, where they can increase the production of collagen, elastin, and intracellular substances thus improving the appearance of the skin.

Thousands of cosmetic actives are used to affect the skin in a variety of ways. They are used to lighten, tighten, and firm the skin.

They can be used to suppress perspiration as in the case of aluminum chlorohydrate.

Salicylic acid and benzoyl peroxide are important ingredients because of their anti-acne activity .

Some active materials are added to skin treatments to protect the skin from the environment.

Dimethicone and petrolatum are examples of skin protectants.

Color Pigments and dyes are used in products to

impart a color.

Titanium dioxide (TiO2) is a white pigment. In combination with synthetic iron oxides, which range in color from red, yellow, black and brown, depending upon the degree of oxidation and hydration, a range of color can be produced that will be suitable for almost every skin tone.

Eyeshadows and lipsticks often contain pearlescent pigments commonly called pearls.

Pearls sparkle and reflect light to produce a multitude of colors.

They are prepared by precipitating a thin layer of color on thin platelets of mica.

Organic pigments are used to color lipsticks and eyeshadows.

When organics are precipitated on a substrate they are called lake pigments.

The term lake refers to the laking or precipitating of the organic salt onto a metal substrate such as aluminum, calcium, or barium. They are called D&C (drug and cosmetic) and FD&C (food, drug and cosmetic) colors.

Some examples are: D&C Red#7 calcium lake and FD&C Yellow #5 aluminum lake.

Dyes are useful in providing tints for lotions, oils, and shampoos.

Preservatives

Most cosmetic products require the addition of preservative to prevent microbial contamination and rancidity.

Parabens and ester of parabenzoic acid are by far the most commonly used because of their effectiveness against gram-positive bacteria.

Phenoxyethanol is used to protect against gramnegative strains.

The cosmetic chemist will generally employ a mixture of preservatives to protect against different bacterial strains as well as yeasts and molds.

Antioxidants such as tocopherol (vitamin E) and BHT (butylated hydroxytoluene) are also added to prevent oxidation of sensitive ingredients as well as protect the skin from free-radical damage.

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