The document discusses respiratory drugs used to treat asthma. It describes asthma as a disease characterized by airway hyperresponsiveness and reversible airway narrowing. The main treatments discussed are bronchodilators like beta-2 agonists, methylxanthines, anticholinergics; and anti-inflammatory drugs like inhaled corticosteroids, cromolyn, and leukotriene inhibitors. It provides details on the mechanisms, pharmacokinetics and uses of these various drug classes.