Preservatives parabens

Hydrocortisone, hydrocortisone-17-valerate, hydrocortisone-17-butyrate, betamethasone-17-valerate, clobetasol- 17-propionate and preservatives (parabenes, benzyl alcohol, sorbic acid, chlorocresol) Innovatech SCX/C18, Hypersil ODS-1, ODS-2, 3 pm... 

Routledge, E.J., Parker, J., Odum, J., Ashby, J., and Sumpter, J.P., Some alkyl hydroxy benzoate preservatives (parabens) are estrogenic, Toxicol. Appl. Pharmacol., 153, 12-19, 1998. 

The literature is replete with reports of various allergic-type reactions to preservatives (parabens, chlorocresol), antioxidants (propyl gallate, metabisulphite), surfactants and solvents. The list is too long to be discussed in this article but Ref. contains a... 

Prickett PS, Murray HL, Mercer NH. Potentiation of preservatives (parabens) in pharmaceutical formulations by low concentrations of propylene glycol. / Pharm Sci 1961 50 316-320. 

Thus, the anionic NaCMC, using dynamic dialysis, has demonstrated the highest limiting binding capacity for the antibiotic chloramphenicol as compared with PEGs, polyvinylpyrrolidones and gelatin [106]. The preservatives parabens sodium influence the viscosity and the zeta potential of NaCMC gels... 

Preservatives Parabens (methylparaben, ethylparaben, butylparaben, propylparaben, etc.), EDTA, Formaldehyde, Quaternium 15, Methylisothiazolinone Skin irritation and allergic reactions. Can be neurotoxic. Some, like parabens, are suspected hormone disrupters. Also found in all cosmetics and toiletries. 

B. Prophylaxis during nitroprusside infusion. Administer 25 mg/h IV. Note Low-strength (1 mg/mL) injection products in the United States may contain the preservative parabens. Unknown safety if parabens-containing product used. 

Some) preservatives Parabens Cosmetics, some antibacterial toothpastes (mimicking oestrogens)... 

First identified Spice included fatty acids (linoleic acid, palmitic acid, oleamide), plant-derivate products (thymol, vanillin), preservatives (paraben family), and vitamins (alpha-tocopherol) [21-24]. Modem Spice products contain only synthetic cannabinoids and plant-derivate substances explaining by home-made manufacturing. 

Preservatives. Most products must contain preservatives to ensure that yeasts, molds, and bacteria do not thrive in them. These preservatives include alcohol, methylparaben, propylparaben, DMDM hydantoin, diazohdinyl urea, and imidazohdinyl urea. The parabens have limited solubiUty in water, eg, 0.25% for methylparaben and 0.05% for propylparaben (22). If these levels are exceeded in the formula, then the addition of solvents is needed to ensure clear, stable products. 

NHydroxyben2oic acid is of significant commercial importance. The most familiar application is the use of several of its esters as preservatives, known as parabens. Also of interest is the use in liquid crystal polymer applications. 

Perfumes, Flavors, Cosmetics, and Soap. Many naturally occurring esters in essential oils and some synthetic esters are important fragrance and flavor compounds (61,62). They are used in perfumes, flavors, cosmetics, soaps, detergents, and air fresheners. Benzyl, butyl, ethyl, methyl, and phenyl esters of benzoic acid are used as flavors, perfumes, and food preservatives. Glyceryl 4-aminobenzoate [136-44-7] and 2-ethyUiexyl 4-dimethylaminobenzoate [21245-02-3] are used in cosmetic sunscreen preparations. Alkyl esters of 4-hydroxybenzoic acid, called parabens, have been used under various names for fungus infections of the skin, and as preservatives in lotions and creams (101). Soap and cosmetic fragrances use large amounts of amyl and benzyl saHcylate. Benzyl saHcylate [118-58-1] is also used in deodorant sprays. 2-Ethylhexyl saHcylate [118-60-5] and 2-ethylhexyl 4-methoxycinnamate [5466-77-3] are used in sunscreen formulations (102). 

Some simple foods can be preservatives in their own right. Honey, salt, sugar, lactic acid, and vinegar are all examples of foods that inhibit microbial action. Some health professionals recommend consuming phytoestrogens from foods such as soybeans to achieve various health benefits. The phytoestrogens in the paraben family, found in blueberries, kill molds and fungi and are often added to food as preservatives. 

Imidazolidinyl urea kills gram-negative bacteria. It acts synergistically with parabens to provide a broad-spectrum antibiotic that is effective against mold, yeast, and bacteria. The combination of the two chemicals constitutes the most widely used preservative in cosmetics. 

Parabens are phytoestrogens found in plants such as blueberries they are used as preservatives in food, cosmetics, sunscreens, shampoos, and many other products. 

These parabens, the methyl, ethyl, propyl and butyl esters, are less readily ionized having pK values in the range 8-8.5 and exhibit good preservative activity even at pH... 

The use of preservative eombinations may be used to extend the range and speetrum of preservation. Thus, in the series of alkyl esters of 4-hydroxybenzoic (/ -hydroxybenzoic) acid (parabens), water solubility deereases in the order methyl, ethyl, propyl and butyl ester. By eombining these produets it is possible to aehieve a situation where both the aqueous and oil phase of an emulsion are proteeted. 

Combinations may also be used to extend the speetrum of a preservative system. Thus, the preservative Germall 115 has an essentially antibacterial activity and very low, if not zero, antifungal aetivity. By combining Germall 115 with parabens, whieh possess antifungal activity, a broader spectrum (antibacterial/antifungal) preservative system is obtained. 

PARABEN ESTERS Typical use concentrations 0.1 - 0.3% Low toxicity Dermatologically safe at typical use concentrations Over 70 years widespread use with an extremely low incidence rate of skin response GRAS (Generally Recognised As Safe) in the USA Stable and active over a wide pH range Stable to heat Combinations of esters exhibit increased activity Approved for cosmetic applications worldwide Low water solubility Some nonionics inactivate to varying degrees May require addition of other preservatives, eg. bactericides Incompatible with some proteins... 

The raw materials used in a particular product may present some challenges to the formulation chemist when selecting the most appropriate preservative. Problem ingredients may act as microbial nutrients, preservative inactivators or preservative adsorbers and careful testing and assessment of the preservative system is necessary in these cases. One notable example of this is the inactivation of parabens esters by certain non-ionic surfactants. 

There is a wide range of technical benefits to be gained by both the formulator and the consumer by using a preservative combination. A clear example of this is detailed in the following table. This demonstrates the well-known inactivation of parabens by non-ionics... 

Substances that have been used as preservatives for disperse systems include chlorocresol, chlorobutanol, benzoates, phenylmercuric nitrate, parabens, and others [76,77]. The use of cationic antimicrobial agents such as quaternary ammonium compounds (e.g., benzalkonium chloride) is contraindicated in many cases because they may be inactivated by other formulation components and/or they may alter the charge of the dispersed phase. Clay suspensions and gels should be adequately preserved with nonionic antimicrobial preservatives. The use of preservatives is generally limited to products that are not intended for parenteral use. Intravenous injectable... 

In emulsions, partitioning of the incorporated preservative can occur between the aqueous and the oil phase. A lipophilic preservative may pass into the oil phase so that a significant portion is removed from the aqueous phase. Since it is the latter in which microorganisms tend to grow, the use of water-soluble preservatives can be more effective, especially for O/W emulsions. For most emulsion systems, the esters of p-hydroxybenzoic acid (parabens) appear to be the most satisfactory. Since microorganisms can also reside within the oil phase, it is further recommended that a pair of preservatives having different oil and water solubilities be used in order to ensure appropriate concentrations in both phases. 

When preservatives are employed, parabens are often selected. 

More subtle effects of preservatives on injectable formulations are possible. Formulation of insulin is an illustrative case study. Insulin is usually formulated as a multiple-dose vial, since individual dosage varies among patients. Preservation of zinc insulin with phenol causes physical instability of the suspension, whereas methyl-paraben does not. However, the presence of phenol is required for obtaining protamine insulin crystals [9]. 

For a liquid or semi-solid pharmaceutical dosage form, it is crucial to include a preservative in the formulation. Commonly used preservatives in these systems include sodium benzoate, EDTA, sorbic acid, and parabens. A generic HPLC method is also recommended for the preservatives used in liquid formulations for routine monitoring to ensure the stability of the preservative itself and it must be validated specific to its use with the dosage form. (See chapters on Sample Preparation and Method Development.)... 

Determination of preservatives (sorbic and benzoic acid, parabens) in food products Determination of phenylurea herbicide residues in vegetables and vegetable processed food Separation of flavonoids from extracts of Adinandra nitida leaves... 

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