Method of purifying a surfactant derived from castor oil and ethylene oxide using a membrane, for use in stabilized liquid pharmaceutical formulations

摘要

Disclosed is a method of treating a surfactant for use in a stabilized liquid pharmaceutical formulation of a lipid-soluble drug for injection, said surfactant being a condensation product of castor oil and ethylene oxide and said lipid-soluble drug being susceptible to degradation in the presence of said surfactant in untreated form, which comprises purifying the surfactant by mixing the surfactant with a solvent and bringing said mixture into contact with a semi-permeable membrane so as to allow impurities present in the surfactant and having a molecular weight lower than the molecular weight cut-off of the membrane to pass through the membrane, whilst retaining purified surfactant.