Inhaled Nitric Oxide Therapy in Adults

The therapeutic promise of nitric oxide (NO), a potent vasodilator, remains uncertain for adults, and licensed indications are restricted to pediatric practice. This review considers the biologic actions of inhaled nitric oxide, the clinical indications for its administration in adults, and an assessment of its potential therapeutic development. This review considers the biologic actions of inhaled nitric oxide, the clinical indications for its administration in adults, and an assessment of its potential therapeutic development. Background and Historical Perspective Nitric oxide was largely regarded as a toxic pollutant until 1987, when its biologic similarities to endothelium-derived relaxing factor were demonstrated. 1 Subsequently, nitric oxide and endothelium-derived relaxing factor were considered a single entity, modulating vascular tone through the stimulated formation of cyclic guanosine 3',5'-monophosphate (Figure 1). 2 Endogenous nitric oxide is formed from the semiessential amino acid L-arginine by one of three (neural, inducible, and endothelial) isoforms of nitric oxide synthase. The physiologic role of endogenous nitric oxide was first shown when an infusion of an inhibitor of all forms of nitric oxide synthase in healthy volunteers . . .