grown in response to these challenges and is now a significant component of the overall drug development process.
In the past several decades, tremendous progress has been made toward the development of safe, effective, and convenient means of drug administration. Advances have been possible, at least in part, because of our improved understanding of the human body. This article focuses on some key developments in the field of drug delivery, especially those that deal with the development of painless, patient-friendly alternatives to injections for the delivery of macromolecules (Figure 1).
Needles and syringes are the most common method of administering macromolecular drugs; an estimated 12 billion injections are given annually worldwide (Kermode, 2004). Despite their common use, needles have several limitations, including needle phobia (Nir et al., 2003) and accidental needle sticks (Rosenstock, 2000). In addition, concerns have arisen about the unsafe use of needles,