1. PRESERVATIVES
IN
COSMETICS
Dr. Prashant L. Pingale
Associate Professor,
Dept. of Pharmaceutics,
GES’s Sir Dr. M. S. Gosavi College of
Pharm. Edu. and Research,
Nashik-422005
2. 2
DEFINITION & CONCEPT
IDEAL PROPERTIES OF PRESERVATIVES
CLASSES OF PRESERVATIVES
FACTORS AFFECTING EFFECTIVENESS OF PRESERVATIVES
GUIDELINES FOR SELECTION OF PRESERVATIVES
SOME ADVERSE AFFECTS OF PRESERVATIVES
3. 3
DEFINITION & CONCEPT
Used to prevent spoilage
Reasons of spoilage:
Oxidation
Microbial growth
Absence of preservative causes deterioration
Water: responsible for microbe growth
Anhydrous preparations: microbes attack
Prepn contains oils & fats: both
4. 4
A. ANTIMICROBIAL AGENTS
Raw materials
Environment
Equipments
Packaging material
Personnel
What happens if unable to control growth of
microbes?
Unable to stop multiplication
10. 10
FACTORS AFFECTING EFFECTIVENESS
OF PRESERVATIVES
pH
Concentration
Susceptibility of organism
Interference by ingredients of cosmetics
Influence of solid particles
11. 11
GUIDELINES FOR SELECTION OF
PRESERVATIVES
Identify the materials which promotes microbial
growth
e.g. glycerin, gums, proteins, carbohydrates, cellulose.
pH i.e. some are active in acidic or basic
Partition of preservatives
Ratio of total to free preservative
Least toxic should be selected
12. 12
Contamination of formulations
Separation of emulsions,
Product discoloration,
Formation of gasses and odors,
Skin infection to the user.
13. 13
Some Adverse Affects of
Preservatives
Parabens: cracked or inflamed skins
Quaternium-15: contact dermatitis, especially in those with
sensitive skin, an infant's skin
Formaldehyde: environment & health problem
Sorbic acid: allergic reactions
Euxyl K 400: contact dermatitis
Phenoxyethanol & Methyldibromoglutaronitrile
14. B. Antioxidants
Basic terms
Definition
Factors affecting rancidity
Classification of antioxidants
Choice of antioxidants
Ideal characteristics of antioxidants
Antioxidants used in aqueous system
Antioxidants used in non- aqueous system
Antioxidants and synergist
Antioxidants & their concentrations.
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16. Factors affecting rancidity
Presence of pro-oxidants
Oxygen
Moisture
Heat
Light
External pro-oxidants
Micro-organisms
From the above it is very clear that cosmetics
containing fats and oils must be preserved by
adding antioxidants besides antimicrobial agents. 16
17. Classification of Antioxidants
Based on chemical classes:
Phenolic type
Quinone type
Amine type
Organic Acids, Alcohols & Esters
Inorganic Acids & their Salts
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18. Gallates Gallic acid
Methyl gallate
Ethyl gallate
Propyl gallate
Color develop in presence of iron
Mixture of gallate with BHA used.
0.01 to 0.1% generally used.
Food stuffs
Phenolic type antioxidants
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19. BHA BHT
Not used alone
Generally used with gallates
Following mixture is generally
used:
BHA 20%
Propyl gallate 6%
Citric acid 4%
Propylene glycol 70%
Used for fatty acids & oils
No phenolic smell
Stability towards heat
Low toxic
0.01 to 0.1% used with
sequestering agents like citric
acid or EDTA.
Phenolic type antioxidants
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21. Quinone type antioxidants
Tocopherol : natural source
Hydroxy chromans
Hydroxy coumarones
Solvent extracted wheat germ oil: contains tocopherol
Not used widely due to
Their high cost,
Little usefulness in preservation of vegetable oils
Used in animal fats with synergists like citric acid,
lecithin or phosphoric acid.
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22. Amine type antioxidants
Ethanolamine,
Lecithin,
Glutamic acid,
Hydroxamic acid,
Purines,
Kephalin etc.
Generally used in combination with other antioxidants.
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23. Organic Acids, Alcohols & Esters
Ascorbic acid,
iso-ascorbic acid,
Citric acid,
Malonic acid,
Oxalic acid,
Propionic acid,
Malic acid,
Tartaric acid,
Thiopropionic acid,
Sorbitol,
Mannitol,
isopropyl citrate
di- lauryl thiopropionate
di- stearyl thiopropionate
Used as antioxidants synergist and are used in combination
with other antioxidants
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24. Inorganic Acids & their Salts
Phosphorous acid and salts
Sodium sulphite
Sodium metabisulphite
Phosphorous acid and salts used as
antioxidants synergists.
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26. Choice of antioxidants
Based on:
Nature of fat and/or oil
Physical form of cosmetics
pH of cosmetics
Intended use of cosmetic
Expected shelf life of cosmetics
Storage condition of product
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27. Ideal antioxidants
Stable
Effective over wide range of pH
Soluble in its oxidized form
Reaction products should be colorless & odorless
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28. Antioxidants used in aqueous
system
Sodium metabisulphite,
Ascorbic acid,
Cystenic HCl,
iso- ascorbic acid,
Sodium bisulphite,
Sodium thiosulphate
28
29. Antioxidants used in non-aqueous
system
Ascorbyl palmitate,
BHA,
BHT,
Hydroquinone,
Lecithin,
Propyl gallate,
- tocopherol
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34. A surfactant or surface active agent is a substance
that, when dissolved in water, gives a product the
ability to remove dirt from surfaces such as the
human skin, textiles, and other solids.
34
35. Definition
Surfactants are wetting agents that lower the surface tension of a
liquid, allowing easier spreading, and lower the interfacial tension
between two liquids.
Surface tension is an attractive property of the surface of a liquid. It
causes the surface portion of liquid to be attracted to another surface,
such as that of another portion of liquid.
Interfacial tension a phenomenon at the surface of a liquid caused by
intermolecular forces.
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36. Surface active agents
Widely used in shampoos, dentifrices
Characterized by
foam production,
reduction in surface or interfacial tension
Amphiphilic in nature
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37. Role of surfactants
Functions as:
Emulsifiers,
Detergents, foaming, cleaning agents
Wetting agents
Solubilizers.
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38. EMULSIFIERS
Anionic
Used in hand creams, lotions.
Fatty acid soaps, sulphuric esters (Na salts)
Cationic
Substantive to protein at acid pH
Produce emulsions with acid pH
Germicidal if not inactivated by anionic.
Non- ionic
Used with cationic
Polyoxyethylene lauryl alcohol, Polyoxyethylene stearate,
propylene glycol monostearate. 38
39. Foaming & Cleaning Agent or
Detergents
Generally used in shampoos.
Detergents have molecules with one side that prefers water
(hydrophilic), and another side that prefers oils and fats (hydrophobic).
The hydrophilic side attaches to water molecules, and the hydrophobic
side attaches to oil molecules.
This action allows the oil droplets to break up into smaller droplets,
surrounded by water.
These smaller droplets are no longer stuck to the material to be
cleaned, and are washed away. 39
40. Ammonium Lauryl Sulfate:
used in many shampoos, toothpastes, and skin cleansers.
Ammonium Lauryl Sulfate + ethylene oxide = ammonium
laureth sulfate (ammonium lauryl ether sulfate)
Lauryl glucoside:
used in shampoos as a detergent and as a thickening agent
40
41. Surfactants
molecules with both a polar and a nonpolar end polar
portion is hydrophilic (water-loving)
nonpolar, hydrocarbon end is hydrophobic (water-hating or
fearing) or lipophilic (oil-loving) …CH3CH2CH2CH2CH2-etc.
41
42. How surfactants work
Excess surfactant
molecules form droplets
called micelle
Hydrophobic ends accumulate on the surface
42
45. Amphoteric surfactants
Anion (Cl-)
Cation (Na+)
Hydrophobe
Carry cationic charge in acidic media
Carry anionic charge in basic media
Form zwitterionic species at neutral media
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46. Amphoteric surfactants Examples
N- alkyl amino acids:
best foaming in slightly alkaline pH
Betains:
Cationic in acidic & anionic in alkaline soln
pH independent
Widely used
Imidazoline derivatives
Stable in wide pH range of 2 to 12
Used in baby shampoos.
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47. Anionic surfactants
Soap, alkyl sulphonates not used in shampoos.
alpha- olefin sulpohontes, alkyl sulphate are used in
shampoos.
Sulphosuccinates are widely used in shampoo due
to safety to the eyes.
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48. Cationic surfactants
Have inferior cleaning and foaming property.
Have affinity to proteins: results in re-deposition of
dirt on hair fibre.
Irritant to eyes so limited used.
Used as additives
Alkyl trimethyl ammonium, stearyl dimethyl benzyl
ammonium etc..
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49. Non- ionic surfactants
Polyglyceryl ether: widely used
No irritation to eye mucosa.
Used as main surfactants in shampoos.
Ethoxylated fatty acid, pluronics, sorbitol esters
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50. Wetting agents
All surfactants have wetting properties.
Alkyl ether sulphate, alkyl aryl sulphonates
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53. References
Cosmetics-Formulation, Mfg and QC: PP Sharma
The Theory and Practice of Industrial Pharmacy: Leon
Lachman
The Science and Practice of Pharmacy: Remington
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