Methylparaben

Synonyms: Aseptoform M; CoSept M; E218; 4-hydroxybenzoic acid methyl ester; metagin; Methyl Chemosept; methylis parahydroxybenzoas; methyl p-hydroxybenzoate; Methyl Parasept; Nipagin M; Solbrol M; Tegosept M; Uniphen P-23.

Description: Methylparaben occurs as colorless crystals or a white crystalline powder. It is odorless or almost odorless and has a slight burning taste.

Chemical Name: Methyl-4-hydroxybenzoate

Antimicrobial preservative. 

• Methylparaben is widely used as an antimicrobial preservative in cosmetics, food products, and pharmaceutical formulations.

• It may be used either alone or in combination with other M Methylparaben 441 parabens or with other antimicrobial agents.

• In cosmetics, methylparaben is the most frequently used antimicrobial preservative.

• The parabens are effective over a wide pH range and have a broad spectrum of antimicrobial activity, although they are most effective against yeasts and molds.

• Antimicrobial activity increases as the chain length of the alkyl moiety is increased, but aqueous solubility decreases; therefore a mixture of parabens is frequently used to provide effective preservation.

• Preservative efficacy is also improved by the addition of propylene glycol (2–5%), or by using parabens in combination with other antimicrobial agents such as imidurea.

• Owing to the poor solubility of the parabens, paraben salts (particularly the sodium salt) are more frequently used in formulations.

• However, this raises the pH of poorly buffered formulations.

• Methylparaben (0.18%) together with propylparaben (0.02%) has been used for the preservation of various parenteral pharmaceutical formulations

The antimicrobial activity of methylparaben and other parabens is considerably reduced in the presence of nonionic surfactants, such as polysorbate 80, as a result of micellization.

However, propylene glycol (10%) has been shown to potentiate the antimicrobial activity of the parabens in the presence of nonionic surfactants and prevents the interaction between methylparaben and polysorbate 80.

Incompatibilities with other substances, such as bentonite, magnesium trisilicate, talc, tragacanth, sodium alginate, essential oils, sorbitol and atropine, have been reported.

It also reacts with various sugars and related sugar alcohols.

Methylparaben and other parabens are widely used as antimicrobial preservatives in cosmetics and oral and topical pharmaceutical formulations. Although parabens have also been used as preservatives in injections and ophthalmic preparations, they are now generally regarded as being unsuitable for these types of formulations owing to the irritant potential of the parabens. These experiences may depend on immune responses to enzymatically formed metabolites of the parabens in the skin. Parabens are nonmutagenic, nonteratogenic, and noncarcinogenic. Sensitization to the parabens is rare, and these compounds do not exhibit significant levels of photocontact sensitization or phototoxicity

Observe normal precautions appropriate to the circumstances and quantity of material handled. Methylparaben may be irritant to the skin, eyes, and mucous membranes, and should be handled in a well-ventilated environment. Eye protection, gloves, and a dust mask or respirator are recommended.

Butylparaben; ethylparaben; methylparaben potassium; methylparaben sodium; propylparaben.