Comparison of in vitro surface properties, in vivo physiological properties and ultrastructues of artificial pulmonary surfactants.

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Various pulmonary surfactant preparations have been used for the prevention and treatment of neonatal respiratory distress syndrome. At least five different natural surfactant preparations are currently produced commercially for use in places such as Japan, the United States and Europe. However, no direct comparison of these preparations has yet been published.The purpose of this study was to compare the in vitro surface properties, in vivo physiological properties and ultrastructures of these preparations. The surfactant preparations used were: Surfacten (Japan), Survanta (USA), Infasurf (USA), Alveofact (Germany), and Curosurf (Italy). The in vitro biophysical properties were assessed using a modified Wilhelmy surface balance, with reference to adsorption, spreading, minimum surface tension, maximum surface tension, area at 10 mN/m and compressibility The in vivo physiological properties were examined in rabbit fetuses delivered on the 27th day of gestation, with regard to lung volum … More e and morphology of the lung after instillation with 50 or 100 mg/kg of one of 5 different preparations. The structure of each preparation was observed by electron microscopy.Surfacten possessed the appropriate in vitro surface-active properties for a pulmonary surfactant (rapid adsorption, rapid spreading, minimum surface tension < 10 mN/m with only 25% surface compression, and low compressibility). The lung volume improved to mature levels after instillation of 50 mg/kg or100 mg/kg in each surfactant-treated fetuses. However, lung morphology showed that the alveolar expansion was significantly larger and more uniform in Surfacten-treated fetuses than in other surfactant-treated fetuses. Infrastructure of all preparations exhibited myelin-like structures, consisting of electron-dense and-lucent multi-lamella with about 50Å periodicity. However, two general structure types were observed: lamellar membranous structure (Surfacten, Survanta), and vesicular or onion bulb-like structure (Infasurf, Alveofact, Curosurf).The results of this study suggest that Surfacten is the optimal surfactant preparation. The observed heterogeneity of surface activity and structure could be ascribed to differences in purification methods, the constituents of lipids, method of drug supply (powder or liquid), and/or the use of autoclaving. Less