Recent Advances in the Transdermal Delivery of Protein Therapeutics with a Combinatorial System of Chemical Adjuvants and Physical Penetration Enhancements

Abstract Since the development of protein‐based therapeutics, research has been underway to deliver protein therapeutics into the systemic circulation and target sites have been actively conducted. Most protein‐based therapeutics require parenteral administration, due to their intrinsic vulnerability and susceptibility to enzyme‐mediated degradation. Among the routes of administration, the transdermal delivery system has been regarded as a promising technique to deliver protein therapeutics, offering the advantages of painless administration, ease of termination, and avoidance of first‐pass metabolism. However, unlike small molecular drugs, protein therapeutics have limited skin penetration, due to their macromolecular and hydrophilic properties. Both cheimcal adjuvants (CAs)‐treatment methods and physical penetration enhancer methods (PPEs) have been utilized to increase skin permeabili…