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Preservatives and Their Concentrations used in Liquid Preparations


Know about different types of preservatives and their recommended concentration in oral liquid dosages forms and parenteral preparations.
Pharmaceutical preparations have many ingredients those promote the microbial growth. Due to this, these non-sterile products are susceptible to the microbial growth. To prevent this microbial growth, it is required to add some antimicrobial compounds known as preservatives. These preservative does not have any harmful effect on patients consuming the products.
Preservative concentrations in different dosage formsThe key criteria for antimicrobial preservative selection are the preservative's dose, antimicrobial functionality, and effect on the active ingredient. Additionally, the use of spectroscopic techniques (circular dichroism (CD) and fluorescence) and differential scanning calorimetry (DSC) were identified as common techniques used in evaluating an antimicrobial preservative for its impact on the conformational stability of peptide, protein, and vaccine antigens.

Phenol and benzyl alcohol are the two most common antimicrobial preservatives used in peptide and protein products while phenoxyethanol is the most frequently used preservative in vaccines.

Benzyl alcohol or a combination of methylparaben and propylparaben are generally found in small volume parenteral formulations. Their presence is mandated for multidose liquid and semi solid products.

An effective preservative must reduce a microbial population significantly and prevent subsequent re-growth and these effects must be both microcidal and microstatic in nature.

Related: Different Types of Dosage Forms in Pharmaceuticals

Synergism in Preservatives
When they combined, they help to meet performance standards. Benzalkonium chloride is ineffective against some strains of Pseudomonas aeruginosa, Mycobacterium and Trichophyton  but when used in combinations with EDTA, benzyl alcohol, 2-phenylethanol enhances anti-pseudomonas activity. Synergy is also observed in combination with cetrimide, 3-cresol, chlorhexidine and organo mercurials

The amino benzoic acid esters (parabens) are more active against gram-positive than gram-negative bacteria. They are more active against yeasts and molds than bacteria. Activity increases with increased alkyl chain length but on increasing alkyl chain aqueous solubility decreases, and consequently the parabens are also often used in combination.

Preservatives and their concentrations used in parental preparation

Sr. No.
Name
Recommended Concentration
1.
Benzyl Alcohol
0.5 to 10%
2.
Benzalkonium Chloride
0.01%
3.
Butyl Paraben
0.015%
4.
Chlorobutanol
0.25 to 0.5%
5.
Meta Cresol
0.1 to 0.25%
6.
Chlorocresol
0.1 to 0.18%
7.
Methyl Paraben
0.01 to 0.5%
8.
Phenyl Ethyl Alcohol
0.25 to 0.002%
9.
Propyl Paraben
0.005 to 0.002%
10.
Phenol
0.065 to 0.02%

Preservatives and their concentrations used in liquid oral preparation

Sr. No.
Name
Recommended Concentration
1.
Benzoic Acid
0.1 to 0.2%
2.
Sorbic Acid
0.1 to 0.2%
3.
Methyl Paraben
0.25%
4.
Propyl Paraben
0.5 to 0.25%
5.
Sodium Benzoate
0.1 to 0.2%
6.
Bronidiol
0.001 to 0.05%
7.
Propylene Glycol
0.25%
Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
Email: .moc.enilediugamrahp@ofni Need Help: Ask Question


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