The Castor Oil Surfactant Family
The family name is usually used as a generic reference to a class of polyoxyethylene castor oil-based substances, of which polyoxyl 35 castor oil is a specific product. The family is produced by reacting castor oil with ethylene oxide, creating a range of non-ionic surfactants with different degrees of ethoxylation. The different members of the family differ in their hydrophilic-lipophilic balance, which determines their emulsifying and solubilizing behavior. Polyoxyl 35 castor oil, with about 35 moles of ethylene oxide per mole of oil, is the member most widely used in pharmaceutical and cosmetic formulations, and it is important for buyers to specify the exact product and grade rather than relying on the family name.
Properties of Polyoxyl 35 Castor Oil
Polyoxyl 35 castor oil is a pale yellow, viscous liquid or semi-solid at room temperature, depending on the specification. It is soluble or dispersible in water, forming clear or slightly opalescent solutions, and it is miscible with many organic solvents. As a non-ionic surfactant, it has low irritancy and broad compatibility with other formulation ingredients, which is why it is preferred in pharmaceutical and cosmetic products. Its hydrophilic-lipophilic balance of around 12 to 14 makes it an effective oil-in-water emulsifier and solubilizer.
Use in the Pharmaceutical Field
As an excipient of drug preparation, polyoxyl 35 castor oil is used in the preparation of injections, oral liquids, suppositories and other dosage forms. It can help dissolve insoluble drugs and improve the stability and bioavailability of drugs, and it is used in certain drug delivery systems, such as liposomes and nanoparticles, as a surfactant or emulsifier to help the drug enter the body better and function. In parenteral formulations, it solubilizes poorly water-soluble active ingredients, and its use in injectables is documented with the relevant pharmacopoeia specifications.
Use in the Cosmetic Field
In cosmetics, polyoxyl 35 castor oil can be used as an emulsifier and solubilizer for the preparation of lotions, creams, shampoos and other products. It helps the various ingredients in cosmetics mix better and improves the stability and use of the product. Its mildness and low irritancy make it suitable for leave-on and rinse-off products, and it is used to solubilize fragrances, essential oils and active ingredients into clear aqueous formulations.
Specification and Sourcing
Buyers should specify the exact product name, the ethoxylation degree, the acid value, the water content and the grade when sourcing polyoxyl 35 castor oil. The pharmaceutical grade must meet pharmacopoeia requirements, while the cosmetic grade follows cosmetic ingredient specifications, and the two should not be assumed interchangeable without verification. The supplier should provide the COA and SDS, and the packaging must protect the product from moisture and oxidation.
Frequently Asked Questions
Is polyoxyl 35 castor oil the same as the generic family name? No, the family name is a generic term for polyoxyethylene castor oil products; polyoxyl 35 castor oil is one specific member with a defined ethoxylation degree.
What is polyoxyl 35 castor oil used for? s an emulsifier and solubilizer in pharmaceutical dosage forms and cosmetic products.
Why is it used in injectables? It dissolves poorly water-soluble drugs and improves their stability and bioavailability.
What should buyers specify? The exact product name, ethoxylation degree, grade, and the relevant quality parameters.
Can the pharma and cosmetic grades be interchanged? Not without verification, because the specifications and regulatory requirements differ.
