Excipients For Respiratory Delivery Of Biologics

By Kimberly Shepard, Ph.D. Director, Respiratory Delivery Lonza Small Molecules, and Michael Shultz, Ph.D. Manager, Inhalation, Respiratory Delivery Lonza Small Molecules

Biotherapeutics now account for approximately half of all new pharmaceutical entities in development, and respiratory delivery is an increasingly pursued route for proteins, peptides, and nucleic acids. Yet the approved excipient toolkit for inhalation and nasal administration remains narrow: only 105 FDA-approved options, with significant overlap from injectable applications and limited guidance specific to biologics.

The constraints are real. An API's therapeutic activity depends on its three-dimensional structure, making excipient selection a direct determinant of stability, potency, and shelf life, not just an ancillary formulation decision. Liquid and solid dosage forms present distinct challenges, from managing aggregation and oxidation in solution to balancing glass transition temperatures and dispersibility in spray-dried powders. The development of the formulation and delivery device must also proceed in parallel, adding complexity to an already constrained design space.

Authored by Kimberly Shepard, PhD and Michael Shultz, PhD, both specialists in respiratory delivery, this paper maps the excipient landscape across both dosage types, identifies where current options fall short as more complex molecules enter development, and outlines where early regulatory engagement can reduce downstream risk. Explore the full analysis to understand where the field stands and where it's headed.