Process for the preparation of a pulmonary surfactant

A process for the preparation of an exogenous pulmonary surfactant selected from the group consisting of a modified natural surfactant or a reconstituted synthetic surfactant, comprising:

• i) extracting said modified natural surfactant from mammalian lung in form of dry paste or mixing the dry components of said reconstituted synthetic surfactant;
• ii) purifying the obtained paste or mixture;
• iii) wherein the step ii) of purification is performed by:
• iv) dissolving the paste of the modified natural surfactant or the components of the reconstituted surfactant in an organic solvent comprising 2-methyl-2-propanol,
• v) subjecting the obtained solution to sterilization by filtration;
• and
• vi) drying.