[Drug-induced alteration of the alveolar content of pulmonary surfactant ].

Pulmonary surfactant is a lipoprotein made up mostly of tensio-active phospholipids. It is synthesized by type II pneumocytes and accumulates as lamellar bodies before being excreted into pulmonary alveoli where it fills intercellular spaces and results in a liquid film (about 1 micron thick) covering the alveolar wall. Surfactant turnover occurs through the action of phospholipases from the alveolus or pneumocytes. Level of alveolar surfactant dependents on the ratio of synthesis and degradation of its principal constituent, dipalmitoyl-phosphatidylcholine. Many substances are known to be able of alter this ratio. Among these, synthetic glucocorticosteroids appear to be the most active in increasing alveolar surfactant. The multiple possible sites of action of these steroids explain their relative efficacy in the prevention of respiratory distress in humans. Studies in progress should increase the number and the quality of drugs available for this purpose.