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Patricia Van Arnum was executive editor of Pharmaceutical Technology
Applying quality-by-design and process analytical technology facilitates process understanding and control of various operations in lyophilization.
When FDA announced in 2002 a new initiative, Pharmaceutical Current Good Manufacturing Practices (CGMPs) for the 21st Century, and later issued its report, Pharmaceutical CGMPs for the 21st Century—A Risk-Based Approach, in 2004, it began an effort to enhance product quality and modernize pharmaceutical manufacturing through a science- and risk-based approach under quality-by-design (QbD) principles (1). That effort was further encouraged by the issuance of guidance on process analytical technology (PAT) in 2004 to facilitate new technologies that would enhance process understanding and assist in identifying and controlling critical points in a process (2). These technologies include: appropriate measurement devices, which can be placed at-, in-, or on-line; statistical and information technology tools; and a scientific-systems approach for data analysis to control processes to ensure production of in-process materials and final products of desired quality (1–4). Lyophilization is one specific application of QbD and PAT in parenteral drug manufacturing, and a review of recent literature shows several developments in this field.
In applying QbD to the lyophilization process, the first task is to define the parameters that have the potential to affect process performance and product quality attributes (5). Key points include the freeze-drying process operating parameters, formulation parameters, equipment, and component preparation and devices (5). PAT may be applied through sensors at various stages in freeze-drying, which may include using temperature sensors, pressure-rise analysis, manometric temperature measurements, calorimetry, microscopy, and spectroscopic techniques, such as near-infrared (NIR), Raman, and infrared spectroscopy (6).
An established approach for PAT in lyophilization is offered by SP Scientific's SMART freeze-dryer technology, which is used to optimize the freeze drying cycle. The SMART technology was developed by the University of Connecticut and Purdue University through the Center for Pharmaceutical Processing Research and licensed to SP Scientific. The technology relies on the use of manometric temperature measurement, which calculates the product temperature at the sublimation interface without having to place thermocouples or other temperature sensors in product vials (7). The SMART freeze-dryer technology is used on SP Scientific's Lyostar 3 development freezer. The SMART technology uses information, such as the number of vials, fill volume, fill weight, freezedryer chamber volume, and critical formulation temperature to optimize a cycle (8). It contributes to several key points in lyophilization: selects an optimum freezing cycle based on whether the formulation is crystalline or amorphous; selects the optimum chamber pressure; determines the target temperature of the product; and adjusts the shelf drying during primary drying to keep the product at a predetermined target temperature (8).
SP Scientific has partnered with the industrial-gas company Praxair for another PAT-based tool for lyophilization, Praxair's ControLyo Nucleation on Demand Technology, used to control the nucleation of the product solution in the freeze dryer. The companies first partnered in 2010, which gave SP the exclusive, global rights to commercialize the technology on development lyophilzers. In 2012, the companies expanded their collaboration to allow SP Scientific to equip its clinical, pilot, and production dryers with the ControLyo Technology and to transfer the technology to allow SP to retrofit existing pilot and production units.
IQ Mobil Solutions, based in Holzkirchen, Germany, offers wireless and battery-free temperature sensors (Temperature Remote Interrogation System, TEMPRIS) as a PAT tool for lyophilization. In a recent study, the TEMPRIS system was assessed for measurement accuracy, capability of accurate endpoint detection, and effect of positioning by using product runs with sucrose, mannitol and trehalose (9). Data were compared noninvasive temperature measurement from manometric temperature measurements. The results showed that the TEMPRIS temperature profiles agreed with thermocouple data when sensors were placed center bottom in a vial. In addition, TEMPRIS sensors revealed reliable temperature profiles and endpoint indications relative to thermocouple data when vials in the edge position were monitored (9).
Researchers at Ghent University in Belgium used Raman and NIR spectroscopy as PAT tools in a freezedrying process (10). For the study, Raman and NIR probes were built in the freeze-dryer chamber to allow simultaneous process monitoring of a 5% (w/v) mannitol solution. Raman and NIR spectra were continuously collected during freeze-drying and analyzed using principal component analysis and multivariate curve resolution (10). Raman spectroscopy provided data about the mannitol solid state, the endpoint of freezing, and several physical and chemical conditions (e.g., onset of ice nucleation and onset of mannitol crystallisation). NIR spectroscopy monitored key points in drying, the endpoint of ice sublimation, and the release of hydrate water during storage (10). A later study further examined the use of in-line spectroscopic process analyzers (Raman, NIR, and plasma emission spectroscopy) (11).
Another recent study examined the use of tunable diode laser absorption spectroscopy (TDLAS) for monitoring secondary drying in laboratory-scale freezedrying with the purpose of targeting intermediate moisture contents in the product (12). An earlier study examined TDLAS to determine the average product temperature in primary drying (13).
Researchers recently implemented and evaluated an optical-fiber system as a process-monitoring tool during lyophilization. The study recorded temperature profiles of mannitol, sucrose, and trehalose using various prototypes of optical fiber sensors (OFSs) (14). The data were compared to data obtained with conventional thermocouples or Pirani/capacitance manometry with drying. The researchers reported that the data obtained with the OFS in contact with product were in good agreement with data obtained by thermocouples or Pirani/capacitance manometry. The OFSs showed higher sensitivity, faster response, and better resolution compared to thermocouples (14). Another study examined the use of a soft sensor for in-line monitoring of the primary drying step of a freeze-drying process in vials (15).
1. FDA, Pharmaceutical CGMPs for the 21st Century—Risk-Based Approach: Final Report (Rockville, MD, 2004).
2. FDA, Guidance for Industry: PAT—A Framework for Innovative Pharmaceutical Development, Manufacturing and Quality Assurance (Rockville, MD, 2004).
3. FDA, Progress Report on Process Analytical Technology,www.fda .gov/Drugs/DevelopmentApprovalProcess/Manufacturing/QuestionsandAnswerson CurrentGoodManufacturing PracticescGMPforDrugs/ucm072006.htm, accessed Feb. 13, 2013.
4. P. Van Arnum, Pharm. Technol. 36 (9), 38-40 (2012).
5. F. Jameel and W.J. Kessler, "Realtime Monitoring and Controlling of Lyophillization Process Parameters Through Process Analytical Technology Tools," in PAT Applied in Biopharmaceutical Process Development and Manufacturing: An Enabling Tool for Quality by Design, C. Undey et al., Eds. (CRC Press, Taylor & France, Boca Raton, FL, 2012), pp. 241-243.
6. R.B. Shah et al., "Scientific and Regulatory Overview of Process Analytical
Technology in BioProcesses," in PAT Applied in Biopharmaceutical Process Development and Manufacturing: An Enabling Tool for Quality by Design, C. Undey et al., Eds. (CRC Press, Taylor & France, Boca Raton, FL 2012), p. 5.
7. D. Sesholtz and L. Mather, "'Smart Freeze Drying," Innovation in Pharm. Technol., www.biopharma.co.uk/ wp-content/uploads/2010/07/Smart_ Freezedrying_article_2007, accessed Feb. 13, 2013.
8. M. Shon, "Optimization of Primary Freeze-Drying Cycle Times," Innovation in Pharm. Technol., www.iptonline.com/ pdf_viewarticle.asp?cat=7&article=887, accessed Feb. 13, 2013.
9. S.C. Schneid and H. Giessler, AAPS PhamSciTech. 9 (3), 729-739 (2008).
10. T.R.M. De Beer et al., J. Pharm. Sci. 98 (9),3430-3446 (2009).
11. T.R.M. De Beer et al., Talanta 83 (5), 1623-1633 (2011).
12. S.C. Schneid et al., AAPS PharmSciTech. 12 (1), 379-387 (2011).
13. S.C. Schneid et al., J. Pharm. Sci. 98 (9), 3406-3418 (2009).
14. J.C. Kasper et a l., Eur. J. Pharm. Biopharm. online, DOI 10.1016/j. ejpb.2012.10.009, 15 Nov. 2012.
15. S. Bosca, A.A. Barresi and D. Fissore, Pharm. Dev. Technol. online, DOI 10.3109/10837450.2012.757786, Jan. 22, 2013.