Oxygen (DB09140): A Comprehensive Monograph on its Chemistry, Pharmacology, and Clinical Application

Section I: Introduction and Historical Context: From "Dephlogisticated Air" to Essential Medicine

Oxygen, the most abundant element in the Earth's crust, occupies a unique and paradoxical position within the modern pharmacopeia. It is simultaneously a fundamental component of the atmosphere essential for all aerobic life and a potent, regulated prescription drug with a defined therapeutic window and significant potential for toxicity. This dual identity—as both a life-sustaining substrate and a powerful therapeutic agent—frames the central challenge of its clinical application: the judicious use of a substance that can be life-saving when correcting hypoxia but life-threatening when administered in excess. The journey of oxygen from an unknown component of air to a cornerstone of medical therapy is a story of scientific revolution, contested discovery, and evolving understanding that mirrors the maturation of chemistry and medicine itself. This report provides a comprehensive monograph on oxygen (DrugBank ID: DB09140), detailing its history, physicochemical properties, complex pharmacology, diverse clinical applications, methods of administration, safety profile, and the unique regulatory framework that governs its use.

The scientific understanding of oxygen emerged from an intellectual landscape dominated by the phlogiston theory. In the 18th century, this theory posited that all combustible materials contained a fire-like element called "phlogiston," which was released during burning. What we now call oxidation was then understood as the release of phlogiston, and the remaining ash or calx was considered "dephlogisticated". It was within this paradigm that the first investigations into the nature of air and combustion took place, setting the stage for one of chemistry's most pivotal discoveries.[1]