Typically antioxidants are employed in low concentrations (0.2% w/w) and it is usual for the concentration of antioxidant in the finished product to be markedly less than the initial concentration, due to oxidative degradation during manufacture of the dosage form. Antioxidants may also be employed in conjunction with chelating agents, e.g. ethylenediamine tetraacetic acid, citric acid, that act to form complexes with heavy-metal ions, ions that are normally involved in oxidative degradation

1. ANTI-OXIDANTS
 Antioxidants prevent oxidation of oxygen sensitive substances.
 They protect the drug product by acting as_
 reducing agent (eg. ascorbic acid, sodium bisulphite, thiourea) or
 preferentially oxidized or by blocking an oxidative chain
reaction (eg. Ascorbic acid esters, butylhydroxy anisole and
tocopherols.) which are the true antioxidants.
 They are added to pharmaceutical formulations as redox systems
possessing higher oxidative potential than the drug that they are
designed to protect or as chain inhibitors of radical induced
decomposition.

2. Typically antioxidants are employed in low concentrations
(0.2% w/w) and it is usual for the concentration of antioxidant
in the finished product to be markedly less than the initial
concentration, due to oxidative degradation during
manufacture of the dosage form.
Antioxidants may also be employed in conjunction with
chelating agents, e.g. ethylenediamine tetraacetic acid, citric
acid, that act to form complexes with heavy-metal ions, ions
that are normally involved in oxidative degradation.

3. Ideal characteristics of antioxidants
It should be effective in low concentrations.
It should dissolve readily in the substrate.
It must be non-toxic, non-irritant and non-sensitizing.
It should not impart any taste, odour or colour to the product.
It should be neutral and should not react chemically with other
ingredients present.
It should be stable and effective over a wide range of pH range
and should be of low volatility.

4. MECHANISM OF ANTIOXIDANTS
The effect of antioxidants is to break up the chains formed during
the propagation process by providing a hydrogen atom or an
electron to the free radical and receiving the excess energy
possessed by the activated molecule.

5. Sunil Kumar. / Asian Journal of Research in Chemistry and Pharmaceutical
Sciences. 1(1), 2014, 27 - 44.

6. TYPES OF ANTIOXIDANTS
ANTIOXIDANTS
Natural Synthetic
Primary Secondary
Free radical
Terminators
Oxygen
Scavengers
Chelating
Agent

7. NATURAL ANTIOXIDANTS
Compound Name Natural source
Vitamin C Most fruits (particularly citrus fruits), vegetable ,
tomatoes
Vitamin E Cereal, grains, sprouts, cauliflower, olive oil, sunflower oil.
Beta Carotene Spinach,tomatoes, carrots, apricots, papayas
Flavonoids Potatoes,tomatoes lettuce, wheat, dark chocolate, grapes, red
wine, black tea
Anthocyanins High content in red wines, some in whiskey
Various polyphenols grapes, red cabbage, blueberries, blackberries
Lycopene Tomatoes, papaya, watermelon, pink grapefruit, guava
CoQ10 enzyme Wheat, bran, fish, organ meats(eg. Chicken, liver)

8. Sunil Kumar. / Asian Journal of Research in Chemistry and Pharmaceutical
Sciences. 1(1), 2014, 27 - 44.

9. SYNTHETIC ANTIOXIDANTS
Compound Name Chemical Structure/Family
BHA (Butylated hydroxyanisole) Monohydric phenol
Radical scavenger
BHT (Butylated hydroxytoluene) Monohydric phenol
Radical scavenger
PG (Propyl gallate) Phenol
Radical scavenger
TBHQ(Tertiary butylhydroquinone) Diphenolic
Radical scavenger
OG (Octyl gallate) Diphenolic
Radical scavenger
DG (Dodecyl gallate) Phenol
Radical scavenger
EDTA (Ethylene diamine tetra acetic
acid)
Metal Chelator

10. Sunil Kumar. / Asian Journal of Research in Chemistry and Pharmaceutical
Sciences. 1(1), 2014, 27 - 44.

11. COMMERCIAL ANTIOXIDANTS
Product Name Chemical
Name
Company Chemical
Formula
Indication
P3130 Sigma Propyl Gallate
Powder
SIGMA-
ALDRICH
3,4,5-
(HO)3C6H2CO2
CH2CH2CH3
Protect Oils ,Fats,
Foods,
Cosmetics,
Chemical
B1378 Aldrich BHT
2,6-di-tert-
butyl-4-
methylphenol
SIGMA -
ALDRICH
[(CH3)3C]2C6H2(C
H3)OH
Food Additive,
Cosmetics,
Pharmaceuticals,
Rubber, Electrical
Transformer Oil
B1253 Aldrich Butylated
Hydroxyanisole
SIGMA -
ALDRICH
(CH3)3CC6H3(OC
H3)OH
Free Radical
Scavengers
Sodium
Metabisulfite USP
NF/BP/ACS
Analytical Grade
Sodium
Metabisulfite
/Sodium
Disulfite
MUBY
CHEMICALS
NA2S2O5 Food
Preservative,
Cosmetic,
Industrial
Bleaching Agent.

12. Product Name Chemical
Name
Company Chemical
Formula
Indication
A92902 Sigma -
Aldrich
Ascorbic Acid SIGMA -
ALDRICH
C6H8O6 Food Additive, As A
Source Of Vitamin C
T3251 Sigma
(±)-Α-
tocopherol
Vitamin E SIGMA -
ALDRICH
C29H50O2 Food Preservative to
prevent oils from going
rancid.
Maranox GA Gallic Acid CLARIANT 3,4,5-
(HO)3C6H2C00
H
Protect Oils And
Fats, Foods, Cosmetics,
Hair Products,
Adhesives, And
Lubricants
Maranox PG Propyl-gallate CLARIANT 3,4,5-
(HO)C6H2CO2
CH2CH2CH3
Protect Oils And
Fats, Foods, Cosmetics,
Hair Products,
Adhesives, And
Lubricants
Nipanox BHT BHT CLARIANT [(CH3)3C]2C6H2
(CH3)OH
Food Additive,
Cosmetics,
Pharmaceuticals, rubber,
Electrical Transformer
Oil

13. ANTIOXIDANTS ARE ALSO CLASSIFIED AS:-
ANTIOXIDANTS
For aqueous
formulations
For oil-based
solutions
Eg. sodium sulphite,
sodium metabisulphite,
sodium formaldehyde
sulphoxylate and ascorbic
acid
Eg.butylated
hydroxytoluene (BHT),
butylated hydroxyanisole
(BHA) and propyl gallate.

14. E numbers are codes for chemicals which can be used as food
additives for use within the European Union
Code Name(s) Purpose Status
E300 Ascorbic acid (Vitamin C) antioxidant Approved in the EU.[18]
E301 Sodium ascorbate antioxidant Approved in the EU.[18]
E302 Calcium ascorbate antioxidant Approved in the EU.[18]
E303 Potassium ascorbate antioxidant
E304
Fatty acid esters of ascorbic
acid (Ascorbyl palmitate)
antioxidant Approved in the EU.[18]
E305 Ascorbyl stearate antioxidant
E306 Tocopherols (natural) antioxidant Approved in the EU.[18]
E307 Alpha-tocopherol (synthetic) antioxidant Approved in the EU.[18]
E308 Gamma-tocopherol (synthetic) antioxidant Approved in the EU.[18]
E309 Delta-tocopherol (synthetic) antioxidant Approved in the EU.[18]

15. E310
Propyl gallate antioxidant Approved in the EU.[18]
E311 Octyl gallate antioxidant Approved in the EU.[18]
E312 Dodecyl gallate antioxidant Approved in the EU.[18]
E313 Ethyl gallate antioxidant
E314 Guaiac resin antioxidant
E315 Erythorbic acid antioxidant Approved in the EU.[18]
E316 Sodium erythorbate antioxidant Approved in the EU.[18]
E317 Erythorbin acid antioxidant
E318 Sodium erythorbin antioxidant
E319
tert-
Butylhydroquinone (TB
HQ)
antioxidant Approved in the EU.[18]
E320
Butylated
hydroxyanisole (BHA)
antioxidant Approved in the EU.[18]
E321
Butylated
hydroxytoluene (BHT)
antioxidant Approved in the EU.[18]
E322 Lecithin emulsifier Approved in the EU.[19]

16. PRESERVATIVES
A preservative may be defined as a substance, which is added to a
formulation to prevent bacterial growth and subsequent spoilage
of the preparation.
Preservatives are substances ‘that are added to food items and
pharmaceutical products in order to inhibit, retard or arrest the
process of microbial contamination ,fermentation, acidification,
and decomposition of the products.
 The primary purpose of adding antimicrobial preservatives to
dosage forms is to prevent adverse effects arising from
contamination by micro-organisms that may be introduced
inadvertently during or subsequent to the manufacturing process.

18. MODE OF ACTION
Preservatives interfere with the growth, multiplication and
metabolism of the microorganisms by one or more of the following
mechanism.
They modify the membrane permeability.
Cell Lysis.
They cause the denaturation of enzymes and other cellular
proteins.
They oxidize cellular constituents.
Hydrolysis.

19. http://www.americanpharmaceuticalreview.com/Featured-Articles/38886-
Antimicrobial-Preservatives-Part-One-Choosing-a-Preservative-System/

20. CHOICE OF A PRESERVATIVE
A good preservative must have the following properties:
 It should have a wide range of activity against contaminating
organisms.
 It should be effective in low concentrations.
 It should be compatible with all the other ingredients in the
products.
 It should be odourless, tasteless, colourless and soluble in the
proposed vehicle.
 It should be stable, effective and unaffected by pH.
 It should be nontoxic, non-irritant and non-sensitizing.

21. http://www.americanpharmaceuticalreview.com/Featured-Articles/38886-
Antimicrobial-Preservatives-Part-One-Choosing-a-Preservative-System

22. Category Product Description
1 Injections, other parenterals including
emulsions, otic products, sterile nasal
products, and ophthalmic products made
with aqueous bases or vehicles.
2 Topically used products made with
aqueous bases or vehicles, non sterile
nasal products, and emulsions, including
those applied to mucous membranes.
3 Oral products other than antacids, made
with aqueous bases or vehicles.
4 Antacids made with an aqueous base.
Compendial Product Categories (USP)

23. Preservatives can be classified as_
i) Acids: eg. Benzoic acid, Sorbic acids, Boric acids,
ii) Esters: eg. Methylparaben, Ethylparaben, Propylparaben,
Butylparaben,Sodium benzoate, Sodium propionate, Potassium
sorbate.
iii) Alcohols: eg. Chlorobutanol, Benzyl alcohol, Phenyl ethyl
alcohol.
iv) Phenols: eg. Phenol, Chlorocresol, o-Phenyl phenol.
v) Mercurial compounds: eg. Thiomersal, Nitromersol,
Phenylmercuric nitrate,Phenylmercuric acetate.
vi) Quaternary ammonium compounds: eg. Benzalkonium
chloride, Cety pyridium chloride.
CLASSIFICATION OF PRESERVATIVES

24. Commercially available preservatives
Product
Name
Chemical
name
Chemical
Formula
Sugested use
Level
Company Application
Nipagin M Methyl paraben C8H 8O3 0.1-0.3% Clariant pharmaceutical,
food, personal care,
and cosmetic
industry
Nipasol M Propyl paraben C10H12O2 0.1-0.3% Clariant pharmaceutical,
food, personal care,
and cosmetic
industry
Nipagin A Ethylparaben C9H10O3 0.1-0.3% Clariant pharmaceutical,
food, personal care,
and cosmetic
industry

25. Nipagin
M/Nipasol M
4:1 Blend
Methyl paraben and
Propyl paraben
C8H 8O3
And
C10H12O2
0.1-0.3% Clariant pharmaceutical, personal
care and cosmetic industries
Nipasept Methyl paraben and Ethyl
paraben
And Propyl paraben
--- 0.1-0.3% Clariant pharmaceutical, personal
care and cosmetic industries
Nipastat Methyl paraben & Ethyl
paraben
& n-butyl paraben &
propyl paraben &
Isobutyl paraben
--- 0.1-0.3% Clariant pharmaceutical, personal
care and cosmetic industries
Phenonip Phenoxyethanol &
Methyl paraben
& Ethyl paraben & n-
butyl paraben
& Propyl paraben
&Isobutyl paraben
--- 0.25-1% Clariant pharmaceutical, personal
care and cosmetic industries

26. Nipaguard
SMG
sodium
hydroxymethyl
glycinate
(50%)
0.1-1% Clariant personal care
and cosmetic
industries
Nipaguard
MPA
benzyl alcohol
(and)
methylparaben
(and)
propylparaben
0.3-1% Clariant personal care
and cosmetic
industries
Phenosept 25P phenoxyethanol
and
chloroxylenol
0.2-1.0%
(cosmetics
and personal
care); 2.0-4.0%
(antibacterial)
Clariant shampoos,
lotions, liquid
hand soap and
liquid
detergents
Nipacide MX
chloroxylenol 0.05-2.5% Clariant consumer and
industrial
products

27. Iteol -H
Benzalkonium
chloride
0.13% -- Astra Zeneca
Pharma India
Antibacterial,in
opthalmics,
parenterals etc
THIMEROSAL
, BP88, powder
Thimerosal 0.05-0.1% C9H9HgNaO2 NOAH
TECHNOLOGIES
CORPORATION
Preservative in
vaccines,
Immunoglobulin,
preparations, skin
test antigens,
Antivenins
ophthalmic and
nasal products
Thimerosal
Sodium
Thimerosal 0.05-0.1% C9H9HgNaO2 Hangzhou Uniwise
International Co.,
Ltd.
same
Merthiolate Thimerosal 0.05-0.1% C9H9HgNaO2 Eli Lilly Company same

28. Phenoxetol Phenoxyethanol C8H10 O2 0.25-1 % Clariant pharmaceutical, personal
care and cosmetic
industries
Nipa
Biopure 100
Imidazolidinyl urea -- 0.2-0.5% Clariant personal care and cosmetic
industries
Nipa
Biopure 200
Diazolidinyl urea -- 0.1-0.3% Clariant personal care and cosmetic
industries
Nipaguard
DMDMH
Dimethyl dimethylol
hydantoin
(55% aqueous)
-- 0.15-0.4% Clariant personal care and cosmetic
industries
Nipaguard
CMB
Benzyl alcohol (and)
chloromethylisothiazo
linone (and)
methylisothiazolinone
-- 0.3-0.15% Clariant personal care and cosmetic
industries

30. Preservative Challenge Test
(Antimicrobial Effectiveness Test)
Pharmacopoeial antimicrobial effectiveness tests (AET) or
preservative efficacy tests (PET) involve challenging a product
with a defined number of colony forming units (cfu) of a variety of
test microorganisms (bacteria, yeasts and fungi), enumeration at
time zero and then monitoring kill / survival rate at defined time
intervals up to 28-days

31. The test consists of challenging the preparation in its final
container with a prescribed inoculum of suitable
microorganisms, storing the inoculated product at a prescribed
temperature, withdrawing samples from the container at
specified intervals of time and counting the organisms in the
samples removed. The preservative properties of the product are
considered adequate if, in the conditions of the test, there is a
significant fall or no increase in the number of microorganisms
in the inoculated preparation after storage for the times and at
the temperatures prescribed.
PROCEDURE AS PER IP

32. Test organisms that are recommended by all of the
pharmacopoeias include,
 Gram positive coccus, Staphylococcus aureus.
 Gram negative rod, Pseudomonas aeruginosa.
 Fungi / mold, Aspergillus niger.
 Yeast, Candida albicans.

33. Organism Suitable Medium
Incubation
Temperature
Inoculum
Incubation
Time
Microbial
Recovery
Incubation Time
Escherichia coli
(ATCC No. 8739)
Soybean–Casein Digest
Broth; Soybean–Casein
Digest Agar
32.5±2.5
18 to 24
hours
3 to 5 days
Pseudomonas aeruginosa
(ATCC No. 9027)
Soybean–Casein Digest
Broth; Soybean–Casein
Digest Agar
32.5±2.5
18 to 24
hours
3 to 5 days
Staphylococcus aureus
(ATCC No. 6538)
Soybean–Casein Digest
Broth; Soybean–Casein
Digest Agar
32.5±2.5
18 to 24
hours
3 to 5 days
Candida albicans
(ATCC No. 10231)
Sabouraud Dextrose
Agar;
Sabouraud Dextrose
Broth
22.5±2.5 44 to 52
hours
3 to 5 days
Aspergillus niger
(ATCC No. 16404)
Sabouraud Dextrose
Agar;
Sabouraud Dextrose
Broth
22.5±2.5 6 to 10 days 3 to 7 days
Culture Conditions for Inoculum Preparation USP

34. The preservative is effective in the product examined if_
(a) the concentration of viable bacteria are not
more than 0.1 per cent of the initial concentrations by the 14th
day,
(b) the concentrations of viable yeasts and moulds remain at
or below the initial concentration during the first 14 days and,
(c) the concentration of each test micro-organism remains at
or below these designated levels during the remainder of the
28-day test period.
INTERPRETATION OF RESULTS AS PER IP

35. http://www.americanpharmaceuticalreview.com/Featured-Articles/38886-
Antimicrobial-Preservatives-Part-One-Choosing-a-Preservative-System

36. http://www.americanpharmaceuticalreview.com/Featured-Articles/38886-
Antimicrobial-Preservatives-Part-One-Choosing-a-Preservative-System

37. REFERENCES:-
 Sunil Kumar. / Asian Journal of Research in Chemistry and
Pharmaceutical Sciences. 1(1), 2014, 27 - 44.
 http://www.americanpharmaceuticalreview.com/Featured-Articles/38886-
Antimicrobial-Preservatives-Part-One-Choosing-a-Preservative-System.
 Jain N.K., “A Textbook of Professional Pharmacy”, Published by
Vallabh Prakashan, Reprint 2011, pgno. 192-197.
 Lachman Leon, Liebermann A. Herbert, “The Theory and Practice of
Industrial Pharmacy”, Published by CBS Publishers & Distributors
Pvt. Ltd., Special Indian Edition, 2009.
 United States Pharmacopoeia National Formulary, Published by U.S.
Pharmacopoeial Convention, Volume1,2014, Pgno. 52-54.
 Indian Pharmacopoeia, Published by The Indian Pharmacopoeia
Commission, Ghaziabad, Volume 1,2007, Pgno. 25-26.

38. THANK YOU