2. Outermost & largest organ.
• Protection: Act as physical barrier for internal body
tissues and organs from dehydration & UV
absorption.
• Sensation: Skin contains abundant nerve endings &
receptors that detect stimuli related to
temperature, touch, pressure & pain.
• Regulation of body temperature
(Thermoregulation): In response to high
temperature, evaporation of sweat from skin
surface help lower the body temperature to normal
& production of sweat is decreased when
environment temperature is reduced.
FUNCTIONS OF SKIN
3. • Excretion: Sweat is excreted out of the body with a
loss of certain ions.
• Blood reservoir: Dermis layer of skin comprises of
extensive vascular network, which regulate
homeostasis of body temperature.
• Endocrine function: Skin is considered as endocrine
organ as it secretes hormones, growth factors, and
synthesis of vitamin D.
• Drug delivery route: Certain lipid soluble
substances & low molecular weight drugs have
been successfully absorbed systemically, across the
skin.
5. Skin has three layers:
• The epidermis, the outermost layer of skin, provides
a waterproof barrier and creates our skin tone.
• The dermis, beneath the epidermis, contains tough
connective tissue, hair follicles, and sweat glands.
• The deeper subcutaneous tissue (hypodermis) is
made of fat and connective tissue.
The skin’s color is created by special cells called
melanocytes, which produce the pigment melanin.
Melanocytes are located in the epidermis.
6. EPIDERMIS: It is composed of keratinized, stratified
epithelium. It grows continuously but maintain its normal
thickness by process of desquamation.
On the basis of 4 types of cells, epidermis is further
divided into 4 layers:
a) Stratum corneum: composed of keratinized cells
called corneocytes.
b) Stratum granulosum: non-keratinized portion of
epidermis. The cells of this layer contains keratohyalin
granules, hence the name of layer. This layer is rich in
protein.
c) Stratum spinous: also called prickle cell layer.
d) Stratum basal: also called stratum germinativum,
because of presence of mitotically active cells. Cells
contain melanin.
7. DERMIS: 2nd layer of skin; composed of connective
tissue consisting collagen & elastin fiber. Cells of
dermis includes fibroblast, macrophages &
adipocytes.
Blood vessels, hair follicles are embedded in the
dermis.
The superficial layer of the dermis is termed
papillary layer. The inner portion of dermis is called
reticular layer.
There is a combination of collagen & elastic
fibers in the reticular region which provides the skin
with strength, extensibility & elasticity.
8. HYPODERMIS: The reticular region of dermis is
attached to underlying organs, such as bone and
muscle, by the subcutaneous layer called hypodermis.
It contains connective tissue & adipose tissue
with nerve endings which are sensitive to pressure.
9. SKIN COSMETICS
Cosmetics are described as articles intended to be
rubbed, poured, sprinkled or sprayed on, introduced into
or otherwise applied to the human body or any part there
of, for cleansing, beautifying, promoting attractiveness or
altering the appearance.
The correct use of skin cosmetics fall into two categories:
1) Skin care: which maintain soft, supple & clean skin &
prevention from external exposure of cold, heat, sun,
wind etc.
2) Decoration: which has a purpose to produce a
pleasing appearance by minimizing facial defects.
10. SKIN CREAMS
Creams are those emulsions which are either oil-in-water
or water-in-oil type. Depending upon the main
ingredients, the purpose of these formulations, they can
be broadly classified as:
A. Make up creams (o/w emulsion)
Vanishing creams
Foundation creams
B. Cleansing creams (w/o emulsion)
C. Creams for winter (w/o emulsion)
Cold cream
D. Creams for dry skin
Moisturizing cream
E. All purpose creams
F. Night creams
11. Raw materials used
• Water: Should be either deionized or distilled.
• Oils, fats & waxes: Oil may be of two types- mineral
& glyceride. Mineral oil consists of hydrocarbons
derived from petroleum oil while the glyceride oils
are mostly vegetable oils.
Mineral oil: It is stable, not subject to rancidity, acts
favorably on the skin, is inexpensive, easily available.
Other hydrocarbon include:
• Petrolatum or petroleum jelly
• Paraffin or paraffin wax
• Ozokerite
• Ceresin
12. • Petrolatum: It is insoluble in water & slightly
soluble in alcohol. It acts as emollient, protective &
lubricant to the skin.
• Paraffin: Consist of hydrocarbons of higher
molecular weight.
• Ozokerite: Because of its higher melting point is
designated as a mineral wax. Refined ozokerite
when mixed with different portions of paraffin,
produce ceresin.
13. Fatty substances from plants and
animals
• Glyceride oils & fats may be of animal or vegetable
origin. They consist of combinations of higher fatty
acids & glycerin.
• Stearic acid: used in making vanishing cream. Color,
odor & melting point should be the basis of
evaluating a suitable grade for making vanishing
cream.
• Waxes: used in creams include beeswax, carnauba
wax, candelilla wax, ceresin, ozokerite.
• Beeswax is derived from the honey comb made by
bees.
14. • Lanolin: Derived from wool fat. Anhydrous grade is
free from water, and hydrous lanolin contains
between 25-30% water. It act as an emulsifying
agent. It offers a protective covering to the skin.
When they are made into creams, they are
usually melted by indirect heat at 40-45°C with the
oils, fats & waxes; water is added slowly at the same
temperature with thorough stirring.
• Humectants: Which have the capacity to retain
water. They also impart viscosity, softness &
emolliency to the products, for e.g. glycerol,
propylene glycol, glycols, sorbitol, glucose, invert
sugars, methyl cellulose solutions & fatty acid
esters.
15. • Glycols are dihydric alcohols lying halfway between
ethanol & glycerol. Glycols used in cosmetics are
ethylene glycol (toxic) , diethylene glycol & propylene
glycol (prefer).
• In certain cosmetics preparation, water solution of
methyl cellulose is employed because it forms a thick
viscous mucilage in water that withstands the action of
mild alkalis or acids and it act as a binding agent.
• Emulsifying agents are used in creams because these
emulgents lower the interfacial tension between the
water & the oil or other water insoluble substances
entering the emulsions for e.g. bentonite, kaolin,
hydrated lime, gum tragacanth, gum arabic, gelatin,
methly cellulose, egg albumin.
16. • Surface active agents comprise the most important
class of emulsifying agents, they can be comprised
of soaps, amines (triethanolamines, morpholine),
amino glycol, wetting agents.
• Triethanolamine (TEA): colourless liquid,
hygroscopic.
• Wetting agents: include soap, sulfonated oils, fatty
alcohol sulfates (specially lauryl sulfate). Wetting
agents lower surface tension, foam considerable
foam, with water, helps in the formulation of
emulsion.
17. Make up creams
Vanishing creams
• o/w emulsion
• Primarily consisting of stearic acid.
• Spreads on surface as thin, oil less film.
• Not visible to viewer.
• Used as foundation cream to hold face powder.
• Hard water is not used because it leads to
formation of lime & magnesium salts which have
tendency to invert the emulsion & reduce the
stability of cream.
18. Main ingredients of vanishing creams:
1) Stearic Acid: Amount of it determines the consistency
of cream.
2) Humectants: Used to prevent excessive drying out of
cream. E.g. Glycerin, sorbitol, propylene glycol.
3) Emollients: Absorbed by skin and soften it. E.g. fatty &
oil substances, lanolin, petrolatum, cocoa butter.
4) Preservatives: Used to prevent the cream from
deterioration from bacterial or fungal action. E.g.
Methly parabene, propyl parabene.
5) Perfume: Used to hide the odor of fats and oils.
Perfumes are added at 40°C.
6) Opacifying agents: Titanium dioxide is used to make a
whiter cream.
19. Cleansing Creams
• It should liquefy at body temperature.
• Its viscosity should be low enough to permit easy
spreading but high enough to retain in suspension
particles of dirt & insoluble foreign matter.
• It should penetrate the epidermis, contain enough light
oils to permit flushing the pores.
• It should be an emulsion type with a small % of water.
• It should leave the skin smooth, relaxed, refreshed,
non-greasy & clean.
• It should contain no chemical that would be absorbed
by skin.
• Mineral oil is an essential ingredient.
20. • Cleansing creams are generally of 2 types:
1) Liquefying creams: which do not contain water
2) Emulsified creams: with a large proportion of mineral
oil.
Liquefying creams: All the components are melted
together, mixed until homogeneous & the mixture is then
poured into jars where it is permitted to set.
Emulsified creams: Cleansing cream may be divided in
beeswax-borax type & water in oil type. Absorption bases
are to be recommended for the preparation of w/o
emulsions that are stable, white and fine texture.
21. Clod Creams for winter:
• Term ‘Cold’ is due to cooling sensation caused by
evaporation of water in the cream after it is applied to
the skin.
• w/o emulsion.
• Emulsifying agents used in the cold cream are borax
and beeswax.
• Formulation contain:
– Beeswax
– Mineral oil
– Borax
– Lanolin
– Triethanolamine
– Glyceryl monostearate
– Methyl parabene or propyl parabene
22. Creams for dry skin
• There are numerous environmental factors, aging process,
hormonal disturbances which can cause drying of skin.
• Dry skin can cause itching and thus to treat this condition,
moisturizing creams & moisturizing lotions are used.
• Urea is added in cosmetic preparations and generally
regarded as safe in between 2%-8% concentration.
• Urea may be incorporated into cosmetic preparations for
four major reasons:
– Moisturizing action (Water binding capacity)
– Desquamating agent (dissolves in stratum corneum)
– Antimicrobial action
– Buffering action regulates hydro-lipid balance.
– Keratolytic action
– Penetration enhancer
– Anti-inflammatory action.
23. Vitamins in skin creams:
• The use of vitamins on the skin has been suggested
to aid in preventing, retarding or arresting certain
degenerative changes associated with aging
process, such as dry & scaly skin or the formation of
wrinkles.
• Water soluble vitamins:
– Vitamin B
– Vitamin C
• Fat soluble vitamins:
– Vitamin K
– Vitamin E
– Vitamin D
– Vitamin A
24. • Vitamin A appears to act as a regulator of skin
epithelial tissue. Vitamin A (retinoic acid) is widely
used in the treatment of Acne and has found value
also for use in dry, scaly skin.
• Vitamin A & D are often used together in topical
preparations. This combination will stimulate
epithelial growth & promote healthy granulation &
healing of burned area of the skin.
• Vitamin A, D, E helps in improving its stability.
• Fat soluble vitamins may be incorporated directly
into oil phase.
• Vitamin E is believed to alleviate the outward
indications of aging skin.
25. • Vitamin E is an Anti-oxidant, which aids in the
slowdown of peroxide formation and helps in
maintenance of skin rejuvenation.
• Vitamin E owing to its moisturizing action, aids in
concealing aids in concealing wrinkles, facial lines &
blemishes.
• Vitamin E is used in the maintenance of connective
tissues.
• Vitamin E protects lipids or lipoproteins in cell
membranes, it may exert a beneficial effect on
water binding in the skin.
26. All Purpose cream
• Almost nay cold cream or cleansing cream may be
termed an “all purpose cream”.
• It is a cream, which combines the properties of
specialized creams.
• Ingredients used:
• Water
• Borax
• Beeswax
• Ceresin
• Absorption base
• Mineral oil
• Perfume
27. Night Creams
• Creams which closely stimulate lubricating creams are
the so called “Night creams”.
• Applied at night for emollient effect.
• Function of cream of this type is to supply oils & fatty
materials lacking in the usual dry skin.
• These creams should be applied and left on over-night.
• The active ingredient is a vegetable or animal fatty
product which is essentially absorbed by skin & has
softening effect.
• Ingredient:
• Spermaceti (hardening agent & emollient)
• Cetyl alcohol (emollient & stabilizing agent)
• Lanolin (water holding capacity)
• Parahydroxy benzoic acid (Preservative)
• Vegetable oil & Animal fats & oils (improve texture)
28. Skin protective & hand cream
• Protective creams are used because of its
beautifying effect and protect skin from various
types of injuries.
• Ideal skin protective must possess certain definite
characteristics & properties. It must:
• Be easily spread.
• Remain stable in the presence of certain chemical compounds.
• Provide an oily film.
• It should not be dehydrating.
• Be non-transferable.
• Should be easy to remove.
29. Quality Control & standards of skin care products
The quality of these products are maintained as per
buyers specification. Important quality controlling
parameters are as per the FDA norms.
The requirements of a cream are as follows:-
• It should liquefy at body temperature.
• Its viscosity should be low enough to permit easy
spreading but high enough to retain in suspension
particles of dirt & insoluble foreign matter.
• It should penetrate the epidermis (via natural
openings) and contain enough light oils to permit
flushing of pores.
• It should be an emulsion type.
30. In the formulation of skin cosmetics creams various ingredients are used.
These ingredients (additives) may alter the effect of formulation. So the
evaluation of products must be done. The evaluation is done by two
methods.:-
1. In-Vitro methods
2. In-vivo methods
In-Vitro methods: In vitro tests are done for know the performance of
product. The effect of temperature and humidity on skin must be known.
Various methods are there in In-vitro evaluation.:
a) Tensile strength: this is done by tensile strength tester it provide
information about tensile property of stratum corneum and gives
information about water content of stratum corneum.
b) Hargen’s gas bearing electro dynamometer: This instrument
helpful in knowing viscoelastic properties of skin. It is used both in vitro
and In-vivo.
31. c) Occlusive potential of ingredients: The occlusive raw
materials are evaluated which tells the diffusion rate of raw
materials.
d) Gravimetric analysis method: For determination of water
and relative humidity present in stratum corneum.
e) Thermal analytical method: In this thermal analysis
Thermo gravimetric analysis (TGA), Differential scanning
calorimetry (DSC) and Thermo mechanical analysis are used.
This evaluation is helpful to know any changes in sample with
temperature. This method also determines physical and
chemical properties of samples.
32. In- vivo methods: Helpful for determination of hydration of
skin.
a) Transpirometry: For determination of Trance Epidermal
Water Loss (TEWL) in skin.
b) Scanning electron microscopy: In this skin replica are used,
to know the effect of skin creams. Polyethylene beads are
melted on skin surface and observe effect of cream on skin
under microscope.
c) Optical microscopy: to detect the changes in dry and rough
skin are observed before and after application of cream. This
method helpful for know moisturizing potential of
preparation.
d) Skin friction: Slightly wet skin has high friction compared
to dry skin. This is helpful to know relation between friction
effect of hydration on stratum corneum and process of
moisturization.
e) Sensitivity test: This test performed for measure the
irritancy, sensitization potential and photo toxicity of skin.
33. Evaluation points:
1) Formulation Properties: The formulation properties of the
cream are studied by visual appearance and characteristics.
2) Presence of foreign particles/grittiness: A small amount of
cream is taken and spread on a glass slide free from greeze
and is observed against diffused light to check for presence
of foreign particles.
3) pH of the cream: The pH of various formulations is
determined by using digital pH meter. About 1 g of the cream
is weighed and dissolved in 100 ml of distilled water and
stored for two hours. The measurement of pH of each
formulation is done in triplicate and average values are
calculated.
4) Viscosity: Viscosity of the formulation is determined by
Brookfield Viscometer II + model using spindle no. S 64 at
20 rpm at a temperature of 25° C and the determinations are
carried out in triplicate and the average of three readings was
recorded.
34. 5) Determination of type of emulsion:
Dilution test: In this test the emulsion is diluted either with oil or
water. If the emulsion is o/w type and it is diluted with water, it
will remain stable as water is the dispersion medium but if it is
diluted with oil, the emulsion will break as oil and water are not
miscible with each other.
Dye solubility test: In this test an emulsion is mixed with a water
soluble dye (amaranth) and observed under the microscope. If the
continuous phase appears red, it means that the emulsion is o/w
type as the water is in the external phase and the dye will dissolve
in it to give color. If the scattered globules appear red and
continuous phase colorless, then it is w/o type.
Similarly, if an oil soluble dye (Scarlet red C or Sudan III) is
added to an emulsion and the continuous phase appears red, then it
is w/o emulsion.
35. 6) Rheological behavioral of the cream: The
rheological property is determined to know the
flow behavior of formulation. The viscosity at
different rpms was measured using Brookfield
viscometer.
The rheological behavior of the formulation was studied by
taking 100 g of the cream in the beaker. The rate of shear
was increased gradually and corresponding readings were
noted; then, the rate of shear was decreased readings were
recorded. The graph was plotted between percent torque
and viscosity to determine type of flow.
36. 7) Partition coefficient: It is determined to know
partition behavior of formulation.
8) Stability studies:
Globule size: 1 mg of cream is diluted to 10 mL with glycerin.
A few drops of this are transferred onto a glass slide and is
focused in a microscope. By using eyepiece micrometer, the
diameters of particles are determined.
Phase separation: The formulated cream is kept intact in a
closed container at 25 - 300°C not exposed to light. Phase
separation is observed carefully every 24 hrs for 30 days. Any
change in phase separation is checked.
Moisture absorption studies: About 50 mg of cream is taken
on a watch glass. A beaker is taken with full of water and is kept
in a desiccator without adsorbents and allowed to get saturated.
Watch glass with cream is introduced into the dessicator. It is
left for 24 hrs.
37. Shelf life: The formulated product is stored in different
temperature conditions like room temperature, 45°C and 55°C
to accelerate degradation for 1 month. Samples are withdrawn
periodically every week and observed for drug decomposition
by taking the absorbance under UV spectrophotometer. From
the concentrations, and the temperatures, the shelf life of the
product can be estimated.
Extrudability: It is useful empirical test to measure the force
required to extrude the material from a tube. The formulations
are filled in standard caped collapsible tube and sealed. The
tube is weighed and recorded. The tube is placed between two
glass slides and is clamped. A 500 gm weight is placed over the
glass slide and cap is opened. The amount of cream extruded
are collected and weighed. The % of cream extruded is
calculated and grades are allotted (++++ Excellent, +++ Good,
++ Fair, + Poor).
38. Spreadability: Spreadability denotes the extent of area to
which the formulation readily spreads on application to
skin. The spreadability is expressed in terms of time in
seconds taken by two slides to slip off from the cream,
placed in between the slides, under certain load. Lesser the
time taken for separation of the two slides, better the
spreadability.
