In biological formulation development, the main objective is to find the solution conditions that offer the greatest level of stabilization to support a molecule’s higher-order structure and which will therefore enable the highest proportion of bioactive, native protein to be delivered. Denatured proteins tend to be more susceptible to irreversible chemical processes such as proteolysis, oxidation, and deamidation, which in turn can lead to inactivation and the risk of aggregation, which may result in undesired immunogenic effects.
During formulation development, the biomolecule is exposed to a range of conditions, including:
- Different buffers, temperatures, shears, pH levels, and salt concentrations
- Various excipients that are used to help stabilize the protein, or aid in manufacturing or drug delivery
- High concentrations, to determine how far a drug candidate may be concentrated, in a range of buffers and additives, before protein aggregation occurs
Biophysical characterization techniques are used to determine the optimal formulation conditions and to select the best formulations for further development.
Biophysical characterization systems for formulation development
Long-term stability studies
Once a drug formulation enters clinical trials, it is subjected to long-term stability testing, including accelerated (forced) degradation studies. Extended submicron and subvisible particle characterization have important roles here in monitoring the constituents of the formulation over time. It is important to understand the origin and nature of particles and to determine whether they are inherent, intrinsic or extrinsic.
Biophysical characterization tools are used to monitor protein conformation, predict thermal stability, and measure aggregate formation in response to formulation and storage conditions. These tools include Differential Scanning Calorimetry (DSC), Dynamic Light Scattering (DLS), Size Exclusion Chromatography (SEC), and Nanoparticle Tracking Analysis (NTA).