Defining An Agitation Model for Early-Stage, High Concentration Biologics Formulation Development

Siddhant Sojitra, Associate Scientist III, Injectable Drug Product Development, Alexion Pharmaceuticals, discusses the primary role played by scale-down agitation in the development of high-concentration biologics by simulating mechanical stress on drug products in this interview regarding the poster presentation “Defining a Scale-Down Agitation Model for Early-Stage High Concentration Biologics Formulation Development” at AAPS PharmSci 360 2025. This stress, often encountered as shaking and mixing, occurs throughout the drug product lifecycle, including during manufacturing, transportation, storage, and administration, Sojitra and colleagues explained in their poster presentation. Utilizing this model offers crucial insights into how varying levels of agitation impact drug products. Ultimately, the goal is to develop more stable formulations capable of sustaining these mechanical forces without compromising the drug's quality or effectiveness, he adds.

Mechanical stress testing is essential because constant agitation leads to significant negative impacts on product quality, primarily protein aggregation and particulates formation, Sojitra notes. The shaking can expose the protein’s hydrophobic patches, causing nucleation and aggregation, and may also unfold the protein structure. Aggregation severely compromises the protein’s potency, while the formation of particulates raises the risk of immunogenicity and can violate regulatory guidelines, the study team notes in their poster.

To assess the stability of biologic formulations against these stresses, quality attributes (QAs) are demonstrated through various testings, including analysis of appearance, turbidity, size/charge variance, aggregates formation, and particulates formation, says Sojitra. The researchers specifically utilized analytical methods, such as size-exclusion ultra-performance liquid chromatography, to measure high molecular-weight species (HMWS), micro flow imaging to detect subvisible particles (SVP), and optical density (OD) to assess turbidity.

The study systematically evaluated three physical agitation models: an orbital shaker, a multichannel vortexer, and a bench-top shipping simulator (VR5500). Comparisons showed that both the orbital shaker (at 200 RPM) and the vortexer (at 1200 RPM) subjected samples to more severe mechanical stress than the VR5500, making them suitable for robust formulation development studies. A key finding was that the different models impacted distinct QAs. The orbital shaker was found to predominantly promote the formation of HMWS, whereas the vortexer was more likely to induce the generation of SVP.

Based on the study's findings, the optimal, scientifically justified agitation model for early-stage formulation development was defined. Recognizing the need for smaller sizes due to material constraints in early development, the standard configuration selected was the 2R vial. The data support using the 2R vials with a minimum fill volume of 1 mL, positioned in a horizontal placement, and subjected to orbital shaker agitation at ambient temperatures for up to 24 hours. This setup provides a reliable and consistent method to assess the impact of mechanical stress, thereby helping to identify stable formulations early in the development pipeline, Sojitra and team stated.

Check out Sojitra’s take on the roles and barriers to AI and digital technology in biologics, our summary of his research team’s study, and access all our AAPS PharmSci 360 coverage!

Transcript

*Editor’s Note: This transcript is a direct, unedited rendering of the original audio/video content. It may contain errors, informal language, or omissions as spoken in the original recording.

I am Siddhant Sojitra. I work as an associate scientist three in drug injectable drug product development team at Alexion, AstraZeneca. I have three plus years of working experience in the pharmaceutical industry now. My specialization includes biologics drug product formulation development, especially high concentration monoclonal antibody-based formulations.

I have an engineering background. I did my masters in chemical engineering from Northeastern University of Boston.

So the primary role of scale-down agitation model is to simulate agitation stress on drug products. This mechanical stress is in the form of agitation, which means drug products are getting exposed to shaking, mixing, and this is often encountered during manufacturing, transportation, storage, administration.

So that's where the scale-down agitation model comes in. Having this model gives us crucial insights about how different label of agitation impacts drug products, and can also help us to develop formulations much more stable version of drug products, which can sustain all this shaking without compromising its quality and effectiveness.

The major impact on drug product quality are protein aggregation and particulates formation. So because of this constant shaking and agitation, proteins often get exposed to its hydrophobic patches, which can nucleate segregation. It can also unfold protein, and because of this aggregation, it impacts protein's potency, and particulates formation increases immunogenicity risk, and it can also violate guidelines.

Drug products’ quality attributes are demonstrated by various testings, such as appearance and turbidity, measuring size and charge variance, aggregates formation, particulates formation. This is how the drug products quality attributes are demonstrated.

So for early-stage stress testing, we are keeping material constraints in mind. We focused on smaller size vials, which are widely used and our data shows that at least 1 mL in 2R vials when shaken horizontally, using an orbital shaker up to 24 hours, provides a reliable approach to study early-stage stress testing.

Following mechanical stress, there are various testings done, which includes appearance, turbidity, particulate formation, using microflow imaging techniques or light obscuration techniques, aggregates formation using size-exclusion chromatography. And this gives us an idea how drug product is behaving and how the impact of agitation is on drug product.