Researchers at the National Institute of Standards and Technology (NIST) have developed a method for evaluating the stability of protein-based formulations for storage at room temperature, opening the possibility of making this process quicker and less expensive. The researchers presented their findings at the American Chemistry Society’s National Meeting held in Philadelphia earlier this month.
Lyophilization for protein stabilization is widely used, but researchers Marcus T. Cicerone and Jerainne J. Johnson with NIST’s polymers division, point out there are no well-established rational approaches to formulating the hydrophilic glasses that will host the protein in the dry state.
“For the past 30 years, researchers have been preserving therapeutic proteins by freeze-drying them and coating them with a thin layer of various formulations of glass-like sugars that act to stabilize their molecular structures. This allows them to be safely stored for extended periods of time” according to NIST release. “Pharmaceutical companies, though they have general guidelines, develop their formulations essentially by trial and error and have to wait up to two years to see if the glasses are suitable.”
The researchers pointed out that materials dynamics are universally accepted as important to protein preservation, but when considered in protein formulations, slow structural relaxation is often considered exclusively in relating host dynamics with the time-course degradation for biological materials embedded in a glass. Although a relaxation is useful, it is not sufficient to predict protein stability. In their work, however, the researchers were able to show a correlation between the stability of the proteins in glasses and the fast local dynamics of the glass itself (1).
Specifically, they developed a steady-state fluorescence method for estimating the hydrogen-bond network lifetimes in biopreservation glasses, which yield information on the same time scale as that of neutron scattering. “Instead of needing relaxation measurements that require using neutron scattering—[in] a national facility with limited time availability—we have developed a widely accessible solution in the form of readily available steady-state fluorescence measurements,” said Cicerone in an NIST press release. “This will allow pharmaceutical companies to adopt the new metrology we’ve developed.”
Using the fluorescent probe, the researchers could tell within minutes after freeze-drying whether the freeze-dried protein formulation will be stable, reducing the time and expense associated with the “wait-and see” method used to evaluate stability, according to the NIST release.
New approaches in evaluating protein stability are of continual interest to the pharmaceutical industry. We are interested to learn what you think of this approach or other insights into the field.
1. M.T. Cicerone and J.M. Johnson, “Hydrogen Bond Network Lifetime as an Indicator of Protein Stability in Pharmaceutical Preparations,” presented at the Biophysical and Biomolecular Symposium: Current Challenges in Protein Formulations, American Chemical Society National Meeting, Philadelphia, PA, Aug. 18, 2008.