Because of its ability to improve patient compliance, transdermal drug delivery continues to grow as an alternative to oral and invasive dosage forms, particularly for the treatment of chronic conditions. But future growth of transdermal patches will be restricted by the need to limit candidate drugs to molecules small enough to effectively pass through the stratum corneum, a limitation that excludes passive transdermal patches as a viable option for the growing number of protein and peptide therapeutic compounds that will represent an increasing share of future drug therapies.
