Risk Mitigation of Plunger-Stopper Displacement Under Low Atmospheric Pressure by Establishing Design Space for Filling-Stoppering Process of Prefilled Syringes: A Design of Experiment (DoE) Approach.

There is a concern that low atmospheric pressure typically encountered during shipment could result in plunger-stopper displacement in prefilled syringes impacting sterility and container closure integrity (CCI) of drug product.1 In this work, following DoE principles we first investigated the impact of filling and stoppering operating parameters on creation of bubble height as performance parameters among others in nominal 1 mL and 2.25 mL Type I glass prefilled syringes (PFSs) with staked needle and rigid needle shield (RNS). Bubble height ranging from <2.0 mm to >15.0 mm were produced in syringes by filling water and vacuum stoppering at operating vacuum pressure ranging from 400 mbar to 950 mbar using a pilot scale filling-stoppering machine. We found that for a particular nominal fill volume in prefilled syringe, as the stoppering vacuum pressure increased, bubble height decreased resulting in plunger-stopper placed closer to the fill level. Subsequently, syringes with varying bubble size were exposed to reduced atmospheric pressure ranging from 628 Torr to 293 Torr bracketing the low pressure recommended by ASTM D4169 standard to qualify shipping containers for transportation of drug products. We found inverse linear correlation between bubble height and plunger-stopper displacement under low atmospheric pressure. However, plunger-stopper displacement increased exponentially as atmospheric pressure decreased. The results suggest that air bubble size in filled glass syringes should be minimized in order to mitigate sterility and container closure integrity (CCI) risk to drug product in prefilled syringes.

Use of a Predictive Regression Model for Estimating Hold-Up Volume for Biologic Drug Product Presentations.

A drug delivery system is designed to administer a therapeutic dose according to its label claim. Upon delivery of a parenteral drug product, the volume remaining inside the container that cannot be extracted at the end of drug administration is called the hold-up volume (HUV) and is primarily considered product wastage. To meet the label claim, every drug product container is filled with a slight excess volume. For early-stage products in clinical phase, for which material availability is often a limitation, excess volume in drug product containers has to be determined experimentally using several grams of product. In such scenarios, established models that can predict HUV in primary drug product containers would be valuable for product development. The objective of this study was to determine HUV with 95% confidence intervals across various container closures and drug delivery systems by using aqueous PEG 400 solution mimicking the viscosity of biologic drug products. ISO 2R, 6R, and 10R vials and single-use hypodermic syringes attached to a Luer lock needle (25 gauge, 1½ in.) were used to mimic parenteral drug product container and delivery systems for determination of HUV. Glass prefilled syringes in 1 mL and 2.25 mL configurations were also used to determine HUV with 95% confidence intervals. A linear regression model was developed for determination of HUV as a function of viscosity and as a function of container closure and a needle-based delivery system. This model predicting HUV was confirmed by using monoclonal antibodies of varying formulations and viscosities for container closure and delivery systems tested in this study. The model provided here can be used to determine HUV for a particular container closure for a drug solution with known viscosity that can subsequently be used to evaluate fill volume specifications and label claim for a dosage form.

Effect of protein cryoconcentration and processing conditions on kinetics of dimer formation for a monoclonal antibody: A case study on bioprocessing.

Monoclonal antibodies (mAbs) may be prone to self-association leading to formation of dimers, trimers, or other high molecular weight species during bio-processing. In order to implement appropriate manufacturing control strategies during bio-processing, it is important to understand various real life bio-processing conditions where such self-associations may manifest. One such case study is presented here of increase in dimer content for an mAb during scale-up bio-processing and the approach taken to understand the under-lying mechanism. In this example, a therapeutic mAb demonstrated a consistently higher dimer values (~0.5% higher) in the drug product (DP) during release when compared to the same value measured in the corresponding drug substance (DS) lot. This observation was interesting since the DS was supplied frozen, and the DS and DP share the same formulation composition and therefore investigation of this dimer change was the scope of the characterization study. Variable path length spectroscopy and size exclusion chromatography was used for protein quantification and to monitor %dimer respectively during characterization of fill-finish unit operations. At the start of DP manufacturing process, immediately after thaw of bulk DS, a protein concentration gradient was observed and the concentration ranged from 90 mg/mL (top of container) to 210 mg/mL (bottom of container). The dimerization kinetics in the same DS container was dependent on concentration with higher concentrations demonstrating higher rates of dimerization. After the bulk DS was mixed for further processing, %dimer in purified bulk DS was quantitated to be approximately 1.4% which is identical to levels observed during scale-up manufacturing of DP. After each unit operation, the in-process samples tested for %dimer showed a gradual increase in dimer as a function of time over the next 7 days accumulating to 1.8% dimer at the end of DP manufacturing process. Samples subjected to static incubation at 2-8°C and room temperature (RT; 15-25°C) showed a gradual increase in dimer over the same time frame; however, the rate of increase in dimer at RT was higher compared to samples stored at 2-8°C. The results from this demonstrate two important key findings: self-association kinetics of mAbs could be exacerbated by protein cryoconcentration and temperature conditions during bioprocessing. Since these two parameters are commonly encountered during manufacturing, the proposed mitigation strategy is to ensure homogeneity of the bulk DP during processing. The temperature dependent self-association kinetics of mAb could be mitigated by processing at lower temperature (e.g., 2-8°C) and by storing the finished DP at lower temperature after manufacturing. The results from this study also highlight the criticality of setting slightly wider specifications for DP compared to DS following ICH Q6B guidelines.

Evaluation of a Biologic Formulation Using Customized Design of Experiment and Novel Multidimensional Robustness Diagrams.

Formulation development includes selection of appropriate excipients to stabilize the active pharmaceutical ingredient throughout its recommended shelf life, against potential excursions in its life cycle and sometimes to aid in the delivery of therapeutics into the patient. Identity and quantity of every ingredient in a therapeutic formulation are critical to achieve their intended purpose. Deviations from a target composition can result in manufacturing, safety, and efficacy challenges. It is mandatory to establish robustness of a formulation for the expected changes in its composition arising from the qualified "process variability" of the impacting process steps during manufacture. The approach for carrying out a robustness study evolved through improved understanding of a therapeutic stability and exploration of new tools, including the quality by design elements strongly recommended by regulatory agencies. An approach is presented here to study formulation robustness in multidimensional space using a customized experimental design and novel multidimensional diagrams, which present a unique way of identifying robustness limits. The concept is universally applicable to any multivariate analysis and such diagrams would be useful to comprehend the outcome on all variables at a glance. Interpretation of these diagrams is discussed, some of which are applicable in general to any statistical design of experiment.