This chapter discusses respiratory drugs and includes discussion on bronchodilators (describing β2-agonists, anticholinergic agents, and xanthine derivatives), nitric oxide (history, biochemistry, clinical use of inhaled nitric oxide, administration of inhaled nitric oxide, adverse effects of inhaled nitric oxide, and adjunctive therapies), mucolytics (properties of mucus, types of mucolytics, clinical applications, and side-effects), and helium–oxygen gas mixtures (including nomenclature, rationale, indications, expected effects, presentation, face mask administration, nebulization, patient monitoring during therapy, stopping helium–oxygen therapy, indications for helium–oxygen mask ventilation, indications for helium–oxygen intermittent positive pressure ventilation (IPPV) via endotracheal or tracheostomy tube, patient monitoring during IPPV therapy, stopping helium–oxygen therapy, and published trials).