Polyoxyl 35 castor oil – Solubilizer, emulsifier for human & veterinary injection

1/ Introduction

Polyoxyl 35 castor oil is a nonionic solubilizing and emulsifying agent produced by the reaction of castor oil with ethylene oxide at a ratio of 1:35. The main component of Polyoxyl 35 castor oil is glycerol polyethylene glycol ricinoleate, along with polyethylene glycol esters and fatty acids.

Properties of Polyoxyl 35 castor oil:

• A clear, pale yellow liquid with a characteristic odor.
• HLB value: 12–14.
• Freely soluble in water and organic solvents such as ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethyl acetate, chloroform, toluene, and xylene; slightly soluble in water at elevated temperatures; miscible with fatty acids (e.g., stearic acid, oleic acid), fatty alcohols, certain vegetable oils, and animal fats.

2/ Key Advantages

• Mechanism of solubilization and permeability enhancement: modifies water polarity; adjusts properties such as density, surface tension, viscosity, melting point, and specific heat of the solution; reduces the contact angle between solute and solvent; increases solvate (hydrate) formation of the solute; reduces solute particle size to molecular levels
• Acid value, saponification value, and iodine value are controlled to meet established standards.
• Stable and resistant to rancidity during long-term storage in sealed containers at room temperature.
• Does not precipitate when used in formulations containing electrolytes, salts, or acids.
• Has a very mild characteristic odor, virtually odorless, and therefore does not affect the odor of the finished product.
• Product complies with USP/EP/BP
• Stock available at GSP/ GDP warehouse, prompt delivery, competitive price

3/ Applications

Injectable pharmaceuticals:

• An emulsifier for liquid dosage forms containing oil-soluble vitamins (vitamins A, D, E, and K) and multivitamin products. Polyoxyl 35 castor oil can incorporate high concentrations of these vitamins into the formulation while maintaining clarity.
• Acts as a solubilizing agent for lipophilic active ingredients such as miconazole, hexetidine, clotrimazole, benzocaine, etc.
• To obtain a clear solution, these vitamins/ APIs should first be premixed with Polyoxyl 35 castor oil before incorporating the remaining components of the formulation.

Veterinary medicine: Applications for oil-based injectable medications

4/ Commercial Products