Poloxamer 235

What Is It?

Poloxamers (Poloxamer 101, Poloxamer 105, Poloxamer 108, Poloxamer 122, Poloxamer 123, Poloxamer 124, Poloxamer 181, Poloxamer 182, Poloxamer 183, Poloxamer 184, Poloxamer 185, Poloxamer 188, Poloxamer 212, Poloxamer 215, Poloxamer 217, Poloxamer 231, Poloxamer 234, Poloxamer 235, Poloxamer 237, Poloxamer 238, Poloxamer 282, Poloxamer 284, Poloxamer 288, Poloxamer 331, Poloxamer 333, Poloxamer 334, Poloxamer 335, Poloxamer 338, Poloxamer 401, Poloxamer 402, Poloxamer 403, Poloxamer 407, Poloxamer 105 Benzoate, Poloxamer 182 Dibenzoate) are polymers made of a block of polyoxyethylene, followed by a block of polyoxypropylene, followed by a block of polyoxyethylene. The average number of units of polyoxyethylene and polyoxypropylene varies based on the number associated with the polymer. For example, the smallest polymer, Poloxamer 101, consists of a block with an average of 2 units of polyoxyethylene, a block with an average of 16 units of polyoxypropylene, followed by a block with an average of 2 units of polyoxyethylene. Poloxamers range from colorless liquids and pastes to white solids. In cosmetics and personal care products, Poloxamers are used in the formulation of skin cleansers, bath products, shampoos, hair conditioners, mouthwashes, eye makeup remover and other skin and hair products.

Why Is It Used?

Poloxamers help to form emulsions by reducing the surface tension of the substances to be emulsified and help other ingredients to dissolve in a solvent in which they would not normally dissolve. They also clean the skin and hair by helping water to mix with oil and dirt so that they can be rinsed away. Poloxamer 188 kills microorganisms, or prevents or inhibits their growth and reproduction. Poloxamer 182 Dibenzoate acts as a lubricant on the skin’s surface, which gives the skin a soft and smooth appearance.

Scientific Facts

Many Poloxamers dissolve in water and form gels. These gels revert to liquid when the temperature is lowered and then reform as gels when the temperature is increased.
Safety Information

The Food and Drug Administration (FDA) includes Poloxymers on its list of indirect food additives. These ingredients are permitted for use in sanitizing solutions that have incidental contact with food. Poloxamer 188 is also approved for use as an antibacterial agent in Over-the-Counter (OTC) skin wound cleanser drug products. The safety of Poloxamers has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that Poloxamer 101, 105, 108, 122, 123, 124, 181, 182, 183, 184, 185, 188, 212, 215, 217, 231, 234, 237, 238, 282, 284, 288, 331, 333, 334, 335, 338, 401, 402, 403, 407, Poloxamer 105 Benzoate and Poloxamer 182 Dibenzoate were safe as cosmetic ingredients.

CIR Safety Review: The CIR Expert Panel noted that Poloxamers injected intravenously are rapidly excreted in the urine, with some accumulation in lung, liver, brain and kidney tissue. In humans treated intravenously, the plasma concentration of Poloxamer 188 reached a maximum at 1 hour, then reached a steady state. Poloxamers generally were ineffective in wound healing, but were effective in reducing post-surgical adhesions in several test systems. Short-term intravenous doses up to 4 g/kg of Poloxamer 108 produced no change in body weights, but did result in diffuse hepatocellular vacuolization, renal tubular dilation in kidneys, and dose-dependent vacuolization of epithelial cells in the proximal convoluted tubules.

 A short-term inhalation toxicity study of Poloxamer 101 in air at 97 mg/m3 identified slight alveolitis after two weeks of exposure which subsided in the 2 week post-exposure observation period. A short-term dermal toxicity study of Poloxamer 184 at doses up to 1000 mg/kg produced slight erythema and slight intradermal inflammatory response in histological examination, but no dose-dependent body weight, hematology, blood chemistry, or organ weight changes. A 6 month feeding study of Poloxamer 188 at exposures up to 5% in the diet produced no adverse effects. 

Likewise, Poloxamer 331 (tested up to 0.5 g/kg/day), Poloxamer 235 (tested up to 1.0 g/kg/day), and Poloxamer 338 (at 0.2 or 1.0 g/kg/day) produced no adverse effects. Poloxamer 338 (at 5.0 g/kg/day) produced slight transient diarrhea. Poloxamer 188 at levels up to 7.5% in diet in a 2 year feeding study produced diarrhea at 5% and 7.5% levels, a small decrease in growth at the 7.5% level, but no change in survival. Doses up to 0.5 mg/kg/day for 2 years produced yellow discoloration of the serum, and increased levels of liver enzymes in the serum. Poloxamers were minimal ocular irritants, but were not dermal irritants or sensitizers. A test in bacteria did not identify any mutagenic activity of Poloxamer 407. Several studies suggested anti-carcinogenic effects of Poloxamers. 

Poloxamers appear to increase the sensitivity to anti-cancer drugs of multidrug resistant cancer cells. Clinical tests of dermal irritation and sensitization were uniformly negative. The CIR Expert Panel did note the absence of reproductive and developmental toxicity data, but, based on molecular weight and solubility, there should be little skin penetration. Small amounts of 1,4-dioxane, a by-product of ethoxylation, may be found in the Poloxamer ingredients. The potential presence of this material is well known and can be controlled through purification steps to remove it from the ingredients before blending into cosmetic formulations.

More information about what the Food and Drug Administration (FDA) is doing to assure that cosmetics do not contain unsafe levels of 1,4-dioxane.

FDA Code of Federal Regulation and Federal Register for Poloxamers (Polyoxyethylene-Polyoxypropylene block polymers) 

Poloxamers may be used in cosmetics and personal care products marketed in Europe according to the general provisions of the Cosmetics Regulation of the European Union. 

EU Cosmetic Regulation

More Scientific Information

Poloxamers are polyoxyethlyene, polyoxypropylene block polymers. A block polymer is made of blocks of different polymerized monomers. The benzoate esters are formed from a reaction of benzoic acid and the particular Poloxamer. In cosmetics and personal care products, most Poloxamers function as surfactants (emulsifying, cleansing and/or solubilizing agents). Poloxamer 188 is used as an antimicrobial agent and Poloxamer 182 Dibenzoate functions as a skin conditioning agent – emollient.
Resources

Find out more about the regulation of over-the-counter drugs by the Food and Drug Administration

Find out more about the regulation of Food Additives by the Food and Drug Administration