Fachberichte - Feststoffanalytik - Biotechnologie - Chemical Imaging - Düngemittel - Gefahrstoffe - Lebensmittel - PAT - Pharma - Recycling - RFA - Umwelt

The conclusions of this paper are like this :

NIR for fermentation and lyophilisation processes

Fermentation and cell culture applications

• NIR useful at multiple stages of fermentation-related processes
  
• Upstream: raw materials qualification
• In-process: real-time monitoring of matrix condition and product titer
• Downstream:
  • Qualitative analysis of column material + real time monitoring of the purification process
  • Real-time monitoring of modification process
• Key aspects:
  • Proper preliminary matrix categorisation
  • Increasing availability of papers related to manufacturing implementations

Lyophilisation

• Technology potential: achieve true QbD as alternative to QC testing
• Main challenge: in-line analyser interfacing to freeze-dryer

Generell Aspects in the Biomanufacturing Industry

The biomanufacturing industry still shows some resistance to the implementation of process NIR technology :

Three hurdles can mainly be classified :

• Regulatory absence : biotech companies have been slow to embark on the Process Analytical Technology (PAT) and Quality by Design (QbD) journey in particular due to the absence of a guidance by FDA on the use of PAT for biologics.
• The economic relevance of analytical in-line implementation is not always easy to justify.
• Technological : The applicability of NIR technology is largely dependent on the complexity of the matrix.

The complexity of biologicals

• Proteins can be extremely heterogeneous and have complex structure
• Characterization not easy
• Fermentation media contain multiple ingredients and possible interferents
• Variability of raw materials and seed inoculum
• Broad dynamic range in product titers (mg/l to g/l)
• Biological products are heat sensitive and susceptible to microbial contamination
• Need for aseptic equipments and principles from initial manufacturing steps in contrast
  to most conventional drugs.
• Culture yield very sensitive to process parameters variations (temperature, aeration,
  agitation)

Monitoring of the fermentation process

• Cell density and biomass content
• Example: determination of biomass growth by correlation of FT-NIR spectra with cell
  density during very-high-gravity corn mash fermentation (NCSU-BTEC)
• Determination of fermentation analytes concentration (nutrients, metabolites, byproducts)
• Example: monitoring of total sugars and ethanol from FT-NIR spectra during very-highgravity corn mash fermentation (NCSU-BTEC)

Monitoring of downstream purification process

• Monitor the elution process and fraction collection to reduce loss of API through ionic exchange column (alternative to assay that takes 10 minutes
• Example: Use of FT-NIR to control chromatography column gradient mixing in a
  protein purification process (NNE Pharmaplan)

Data evaluation and Chemometrics

• Spectral region optimisation (exclude C-H combination region below
  4800 cm-1 and strong water band at 5100 cm-1)
• Full spectra algorithms preferred to extract complex matrix information
• Incorporate temperature fluctuations in model
• Consider time-segmented calibrations to handle fast matrix changes
• Use of spectral preprocessing
• Effect of agitation rate, gas flow rates and biomass variations on scattered light variations
• Baseline shifts
• Use process trajectories to detect culture contaminations
• Use on-the-fly statistical evaluation of model applicability to detect extrapolation conditions where model robustness can be challenged
  (e.g. F-ratios)

PAT sensors for lyophilisation processes

Objectives for lyophilisation

• Real-time monitoring of moisture content for end-point determination of freeze-drying process
• 
  Achieve real time feedback control to achieve “right first rime” quality

At-line methods

• Loss on drying (IR) lack of repeatability, destructive, can not distinguish free/bonded water
• Karl-Fischer titration destructive, slow, requires skilled operators

Some PAT sensors

• Temperature / conductivity probes inserted in vials :
  • Potential crystallisation points during freeze-drying
  • Sterility issues
  • Non-representative information
• Mass spectroscopy (Headspace measurement on vaporised water) :
  • No process interference
  • Provides overall process end-point information
  • No direct measurement of CQA
  • Requires constant leak rate frequent leak tests required

Technical challenges – Probe-related aspects

• Availability of sampling points
  • Not possible to retrofit legacy equipment
  • Collaboration with freeze dryer supplier required early in project
  • Ideally have sampling points coupled with windows
• Positioning of sampling points
  • Usually only external vials accessible due to tray design with silicon oil circulation
  between shelves

  Monitoring only (cycle-time reduction) OK
  Feedback control or parametric release Requires careful validation to demonstrate representativity of measurements (drying usually not homogeneous)

  • Reproducibility of probe alignment in front of vial can be challenging (automated tray
  loading, possibly different vial diameters depending on products) Possibility to visually preposition retractable non-contact probe after tray loading and manually fine tune probe positioning by using XYZ 3-D stage and maximising reflectance signal after
  water sublimated (powder), or early in process by focusing beam on stopper.

• Specifications
  • Probe with aseptic design that sustain P and T conditions, including SIP cycle
  temperature gradient
  • Vacuum-tight flange seal

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