Rethinking asthma therapy, part 2: transdermal strategies for adjunct asthma and allergy treatments.

Asthma and allergies affect millions of people globally. Avoiding triggers and allergens is a basic management technique for all asthma subtypes (>80% of asthma patients also suffer from allergies), and pharmacological treatment is the cornerstone for acute exacerbations and ongoing maintenance. Typical treatment options for asthma include inhaled, oral, or injectable dosage forms. However, transdermal drug delivery has great potential to provide an alternative route of administration of necessary asthma and allergy therapies that have traditionally been given in other dosage forms. In Part 1 of this two-part series, we discussed the work done towards incorporating short- and long-acting β2-agonists into transdermal drug delivery systems. Here in part 2, we describe the current literature for transdermal applications of leukotriene antagonists, theophylline, and other adjunct medications that do not fall into one specific drug class. A brief overview of biologics, particularly monoclonal antibodies, and the role in asthma is also included, including some context of transdermal mAb delivery for disease states beyond asthma. Because of the relatedness of asthma and allergies, transdermal applications for allergen immunotherapy is also discussed.