The present invention discloses a method to prepare specific liposomal formulations for the pulmonary application of therapeutic substances. The liposomal components, DPPC and cholesterol at a molar ratio of 7:3 and 7:4, respectively, are combined with the non-toxic excipients, sphingomyelin, dimyristoylphophatidylcholine and/or polyethylene glycol, to prepare liposomes that are stabile during nebulization with commercially available nebulizers and exhibit sustained release kinetics of encapsulated drug substances.
