ABSTRACT
INTRODUCTION With the recent great progress in biotechnology, many important new biodrugs including peptide and protein drugs have been introduced to clinical stages. Because of their susceptibility to enzymatic degradation and low permeability across the epithelium via the paracellular pathway, however, the absorption of these biodrugs from mucosal site is generally poor. Therefore, the administration of these biodrugs is mostly limited to invasive injections, which can be painful and inconvenient. Over the past decades, the nasal route has been gaining much attention as a noninvasive alternative for systemic delivery of various classes of peptide and protein drugs with poor oral bioavailability (1-4). That is because the nasal route has one of the most permeable and highly vascularized mucosa, which would potentiate rapid absorption of biodrug and quick onset of its therapeutic effect. Furthermore, the nasal route circumvents hepatic first pass effect associated with oral delivery.
