SYNTHETIC PULMONARY SURFACE ACTIVE SUBSTANCE AND REMEDY FOR RESPIRATORY DISTRESS SYNDROME (RDS) CONTAINING THE SAME AS ACTIVE CONSTITUENT

PURPOSE:A synthetic pulmonary surface active substance, containing a phospholipid phosphatidylcholine and cardiolipin, and easily available compounds as constituents, and having a specific surface activity without containing foreign proteins. CONSTITUTION:A synthetic pulmonary surface active substance containing 55- 80wt% phospholipid phosphatidylcholine of formula I (R1 and R2 are fatty acid group), preferably a compound in which 80wt% or more thereof is a compound of formula I (R1 and R2 are 14-20C straight chain saturated fatty acid residue), e.g. diplamitoyl phosphatidylcholine, and 20-45wt% cardiolipin of formula II(R1'-R4' are fatty acid group), preferably most of R1'-R4' are 14-20C straight chain fatty acid residuess, and 30wt% or more thereof are unsaturated fatty acid residues as main constituents. In the practical administration as a pharmaceutical, 1pt.wt. substance is used with 2-50pts.wt. pharmacologically acceptable water-soluble powdery substance, e.g. an amino acid or a saccharide, as an excipient, and the resultant pharmaceutical is preferably administered as the powdery synthetic pulmonary surface active substance.