Which of the following is NOT a surfactant?

Mannitol is not a surfactant; it is classified as an osmotic diuretic. Surfactants are substances that reduce surface tension in liquids, and they are primarily used in the context of respiratory therapy to help improve lung function by promoting the stability of alveoli and preventing collapse.

Survanta, Exosurf, and Infasurf are all examples of pulmonary surfactants used in the treatment of neonatal respiratory distress syndrome. They are designed to mimic the natural surfactant produced in the lungs, aiding in lung expansion and reducing the work of breathing. In contrast, mannitol does not fulfill this role; instead, it functions by drawing water into the bloodstream and is used in various clinical settings, such as to reduce intracranial pressure or to manage certain kinds of kidney issues. Understanding the distinction between these substances is crucial in pharmacology, especially when dealing with treatments for respiratory conditions.