Targeting by Deposition

The word targeting in the context of therapeutics can be interpreted as a desire to

achieve distinct concentration-time profiles for a biologically active agent at

different sites in the body to maximize therapeutic effects while minimizing or

eliminating toxicity. Thus, targeting in general implies a certain degree of

specificity of the agent in space and time. If this goal is to be reached by design

rather than by chance, the knowledge of the ideal spatial and temporal patterns

for each drug is required. As discussed in the following, this information for

inhalation therapy of respiratory disease with drug aerosols is incomplete.

Nevertheless, some basic guidelines for optimum physical characteristics of these

aerosols can be laid down. Exploration of systemic delivery of pharmaceutical

drugs has become a major area of academic and industrial research in the last

decade. The mechanistic basis for optimum targeting for this purpose is

obviously quite different from applications intended for therapies of respiratory

disease.