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

5. 5
Names of microbes
Staphylococci
Diphtheroids
Fungi
Yeast
Pseudomonas
U
N
U
S
E
D
U
S
E
D

6. 6
Ideal Properties of Preservatives
 Compatible with formulation
 Extent of solubility
 Stability
 Should give sustained antimicrobial effect
 Colorless & odorless
 Non- toxic, non-irritant, non-allergic

7. 7
CLASSES OF PRESERVATIVES
 Organic acids:
 Benzoic acid,
 Formic acid,
 Vanillic acid,
 Propionic acid,
 Sorbic acid.
 Alcohols:
 Ethyl alcohol,
 IPA,
 Chlorobutanol
 Aldehydes:
 Formaldehyde,
 Cinnamic Aldehyde.

8. 8
 Phenolic compound:
 Cresol,
 Phenol,
 p- chloro-m- cresol,
 p- chloro-m- xylenol
 Esters:
 Methyl p- hydroxy benzoate,
 Ethyl p- hydroxy benzoate,
 Propyl p- hydroxy benzoate,
 Butyl p- hydroxy benzoate.
 Mercury compound:
 Thiomersol,
 Nitromersol,
 Phenyl mercuric salts i.e. nitrate, acetate

9. 9
 Surfactants:
 BTC,
 BAC,
 Cetyltrimethyl ammonium bromide.
 Miscellaneous:
 5- Bromo- 5 nitro- 1, 3- dioxan
 Vanillin,
 Ethyl vanillin

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.
14

15.  Rancid
 Antioxidants
 Consumers choice
 Synergists
15

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
17

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
18

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
19

20.  Methyl p-hydroxy benzote,
 Propyl p-hydroxy benzote,
 Butyl p-hydroxy benzote.
Phenolic type antioxidants
20

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.
21

22. Amine type antioxidants
 Ethanolamine,
 Lecithin,
 Glutamic acid,
 Hydroxamic acid,
 Purines,
 Kephalin etc.
Generally used in combination with other antioxidants.
22

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
23

24. Inorganic Acids & their Salts
 Phosphorous acid and salts
 Sodium sulphite
 Sodium metabisulphite
Phosphorous acid and salts used as
antioxidants synergists.
24

25. Classification based on
mechanism
• Ascorbic acid
• Citric acid
• Tartaric acid
• Oxalic acid
Reducing agent
Blocking agent
Synergistic
Chelating
EDTA
• Ascorbic acid
• Sodium bisulphite
• Sodium metabisulphite
• Thiourea
• Ascorbic acid
esters
• BHT
• BHA
25

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
26

27. Ideal antioxidants
 Stable
 Effective over wide range of pH
 Soluble in its oxidized form
 Reaction products should be colorless & odorless
27

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
29

30. Antioxidants & their
synergists
Antioxidants Synergists
Propyl gallate Citric acid & phosphoric acid
- tocopherol Citric acid & phosphoric acid
Hydroquinone Lecithin, citric acid & phosphoric acid, BHA, BHT
BHA Citric acid & phosphoric acid, lecithin, BHT
BHT Citric acid & phosphoric acid
30

31. Antioxidants & their
Concentrations
Antioxidants Concentration (%)
Propyl gallate 0.005 to 0.15
- tocopherol 0.05 to 0.1
BHA 0.005 to 0.01
BHT 0.01
Sodium metabisulphite 0.01 to 1.0
Sodium sulphite 0.01 to 1.0
31

32. SURFACTANTS

33.  Definition
 Role of surfactants
 Types of surfactants
 Examples
33

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.
35

36.  Surface active agents
 Widely used in shampoos, dentifrices
 Characterized by
 foam production,
 reduction in surface or interfacial tension
 Amphiphilic in nature
36

37. Role of surfactants
 Functions as:
 Emulsifiers,
 Detergents, foaming, cleaning agents
 Wetting agents
 Solubilizers.
37

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

43. Classes of Surfactants
 Amphoteric surfactants
 Anionic surfactants
 Cationic surfactants
 Non- ionic surfactants
43

44. Distribution of surfactants
Distribution of surfactants among the four classes
44

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
45

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.
46

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.
47

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..
48

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
49

50. Wetting agents
 All surfactants have wetting properties.
 Alkyl ether sulphate, alkyl aryl sulphonates
50

51. Solubilizers
 All surfactants above CMC have solubilizing
properties.
51

52. Uses of surfactants
 Detergents
 Fabric softener
 Emulsifiers and
Emulsions
 Paints
 Adhesives
 Inks
 Anti-fogging
 Dispersants
 Wetting agents
• Foaming agents
• Defoamers
• Laxatives
• Agrochemical formulations
• Herbicides
• Insecticides
• Quantum dot coating
• Biocides (sanitizers)
• Hair conditioners (after shampoo)
• Spermicide (nonoxynol-9) 52

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
53