This document discusses preservatives used in pharmaceutical and cosmetic products. Preservatives are chemical agents that prevent microbial contamination and maintain sterility. An ideal preservative is non-toxic, effective at low concentrations against all microorganisms, stable, and compatible with other ingredients. Preservatives are classified as parahydroxy benzoic acid derivatives or other preservatives. Parahydroxy benzoic acid derivatives like methyl and propyl paraben have antifungal properties and low toxicity. Other common preservatives mentioned include chlorobutanol, benzyl alcohol, sodium benzoate, and sodium propionate.

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PRESERVATIVES
BY
KENCHA SWATHI
ASSISTANT PROFESSOR
BANGALORE

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PRESERVATIVES
 Chemical agents that are added to various dosage
forms and cosmetics to prevent microbial contamination
are called preservatives.
 In parentral and ophthalmic preparations they are used
to maintain sterility in the event of accidental
contamination during the use.

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IDEAL PROPERTIES OF A PRESERVATIVE
 They should prevent microbial contamination
 should be non-toxic
 They should be stable
 Should be effective at low concentration against all possible
microorganisms.
 Compatible with other constituents used in the preparation
 A ideal preservative should be stable for the shelf life of the
preparation.

4. z CHEMICAL CLASSIFICATION
 Preservatives are chemically classified as 2 types:
1.Parahydroxy benzoicacid derivatives
2.Other preservatives

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PARAHYDROXY BENZOIC ACID DERIVATIVES
 This class of preservatives are ester derivatives(-COOR).
 They have antifungal properties.
 Their toxicity is generally low due to rapid hydrolysis of the esters and
they are rapidly conjugated and excreted.
 The activity increases by increase in molecular weight .
 But Methyl ester is effective against moulds whereas propyl ester is
more effective against yeast.
Eg: Methyl paraben,Ethyl paraben,Propyl paraben

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Methyl paraben Ethyl paraben
Propyl paraben

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OTHER PRESERVATIVES
Chlorobutanol Benzyl alcohol
2-Phenyl ethyl alcohol

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Phenyl mercuric nitrate Phenyl mercuric acetate
Sodium benzoate
Sodium propionate

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