ABSTRACT
INTRODUCTION Transdermal delivery offers an attractive option for the delivery of biodrugs as it avoids first-pass degradation in the liver or gastro intestinal tract (GIT) and the skin exhibits less enzymatic activity than the other routes of administration. The skin acts as a protective barrier, restricting permeation to only those compounds with favorable physicochemical characteristics such as molecular weight less than 500 Da and suitable lipophilicity. Consequently biodrugs, such as therapeutic proteins and peptides that do not passively permeate the skin, require effective methods to enhance delivery to and across the skin. Strategies include passive methods such as formulation optimization and carrier vehicles, active delivery methods such as iontophoresis and other energy-related techniques, and minimally invasive techniques such as microneedles. This chapter reviews the current state of the art in the delivery of biodrugs to and across the skin.
