Treatment of Inflammatory Airway Disease: Aerosol Delivery Devices and Medications

Successful treatment of inflammatory airway disease (IAD) requires environmental management to minimize exposure to irritants and combination drug therapy to reduce pulmonary inflammation and prevent bronchoconstriction. Aerosolized drug therapy is an efficient means of treatment for most horses with IAD. Aerosolized drug therapy has been standard treatment for human patients with non-infectious respiratory disease for 20 yr. Inhalation therapy improves drug safety and efficacy by reducing the total therapeutic dose, minimizing drug exposure to other body systems, and allowing direct delivery of the drug to the lower respiratory tract. In most instances, the response to aerosolized drug administration is more rapid than systemic drug administration. Equine patients are ideal candidates for inhalation therapy because of their cooperative nature, large tidal volume, and obligate nasal breathing. Early devices designed for delivery of aerosolized drugs to the lower respiratory tract of horses were cumbersome, expensive, and marginally efficacious. Today, efficient systems for drug delivery are rapidly being developed, and inhalation therapy has become increasingly popular for treatment of lower respiratory tract disease. Inhalation therapy for horses has predominately focused on administration of bronchodilating agents and anti-inflammatory drugs for treatment of IAD and recurrent airway obstruction (heaves). The most important features of an aerosol administration system for horses are efficient pulmonary drug delivery and ease of administration. The disadvantages of the aerosol route of administration include access to obstructed airways, expense, frequency of drug administration, airway irritation by some aerosol preparations, and environmental impact of cholorofluorocarbon (CFC) propellants.