Lyophilization PDF - PR5217 Past Paper

PR5217: Lyophilization Associate Professor Matthias G. Wacker, PhD Department of Pharmacy | Faculty of Science [email protected] © Copyright National University of Singapore. All Rights Reserved. © Copyright National University of Singapore. All Rig...

PR5217: Lyophilization Associate Professor Matthias G. Wacker, PhD Department of Pharmacy | Faculty of Science [email protected] © Copyright National University of Singapore. All Rights Reserved. © Copyright National University of Singapore. All Rights Reserved.  Written Questions in PR5217 © Copyright National University of Singapore. All Rights Reserved.  Learing Objectives What exactly is freeze-drying and how is it applied in pharmaceutics? Which dosage forms are typically prepared by freeze drying? How is a freeze dryer designed? Which excipients are typically used for a freeze-dried product? What is PAT and how can it be used during freeze drying? How to optimize a freeze drying process? © Copyright National University of Singapore. All Rights Reserved.  Lyophilization Freeze-drying is a technique preserving the stability and activity of drug substances during the drying process. The liquid phase undergoes a solid- to-gas transition (sublimation). Drying and vacuum sealing process with a lowered risk of microbiological contamination. Solid cake can be reconsituted quickly and easily because of the forming pore structure. Chemical integrity of complex molecules can be maintained. © Copyright National University of Singapore. All Rights Reserved. 4  Powder for injections or infusions Powders for injections or infusions are solid, sterile substances distributed in their final containers and which, when shaken […], rapidly form either clear and practically particle-free solutions or uniform suspensions. Manufactured by freeze-drying. Contain additional excipients to facilitate the drying process. © Copyright National University of Singapore. All Rights Reserved.  Phase diagram Pressure and temperature define whether sublimation Liquid or evaporation occur. Successful drying requires Solid both parameters to be controlled. Gas © Copyright National University of Singapore. All Rights Reserved.  Process © Copyright National University of Singapore. All Rights Reserved. Source: Merivaara et al. 2021, J. Control. Rel. (https://doi.org/10.1016/j.jconrel.2021.06.042)  Freezing Freezing refers to the crystallization of water at reduced temperature. Commonly, the product temperature (TP) should remain below the glass transition temperature (TG) or eutectic temperature (Teu). Industry-scale freeze driers typically come with active cooling while research models combine external freezing (in the freezer with) evaporation energy cooling. © Copyright National University of Singapore. All Rights Reserved.  Freezing Important temperatures The eutectic or glass transition temperatures determine the maximum temperature that the product can withstand during primary drying without loss of structure. Name Description Eutectic temperature The eutectic temperature is the temperature at which two or more crystalline species melt together like a single, pure substance Glass transition temperature The glass transition temperature is the temperature at which there is a transition of amorphous substances from a solid into the liquid state. © Copyright National University of Singapore. All Rights Reserved.  Drying Evaporation at low pressure leads to a drastic expansion of the volume. Without a process reducing this volume, the pressure cannot be controlled. p Gas pressure Pa 105 Pa = 1 bar V Volume m³ p * V = m * Rm * T = const. M Rm Mass Ideal gas constant Kg J/mol*K R=8,314 J/mol*K M Mass per mol g/mol H2O=18 g/mol T Temperature K © Copyright National University of Singapore. All Rights Reserved. 10  Freeze Dryer Key components Drying chamber with heating Condenser Active cooling Pump Vacuum pump © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Freeze Dryer Design Chamber With vials Cascade Condenser compressor window © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Freeze Dryer Condenser design Intermediate valve Sublimation (Endothermic) Condensation (exothermic) Optimal vapor transport  Large valve (large opening)  Condenser close to chamber (small distance) © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Freeze Drying Risks and challenges Transitions of the product into the liquid state: Insufficient cooling Increasing amounts of ions and small molecules (melting point reached at lower temperature, e.g., -20 °C instead of 0°C). Secondary drying process before complete evaporation. Incomplete drying: Drying interval too short. Vacuum not stable due to a too rapid evaporation. Vapor transfer insufficient. © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Freeze Drying Cycle Vacuum [mbar] Shelf temperature [°C] Condenser temperature [°C] © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH Sublimation © Copyright National University of Singapore. All Rights Reserved. Source: Merivaara et al. 2021, J. Control. Rel. (https://doi.org/10.1016/j.jconrel.2021.06.042)  Limiting Factors Mass transfer Product resistance pore size, capillaries, height, excipient concentration and compactness. Stopper resistance Stopper geometry. Size of opening. Chamber resistance Distance of shelves to the ice condenser. Location and capacity of the ice condenser. Geometry of the freeze-dryer. Loading of the freeze-dryer Ice condenser capacity determines maximum loading. © Copyright National University of Singapore. All Rights Reserved.  Limiting Factors Heat transfer Heat may enter your product through: Conduction Convection Radiation Heat-transfer is affected by Shelf temperature Vial geometry (thickness of the vial, bottom of the vial) Geometry of the freeze-dryer Loading of the freeze-dryer © Copyright National University of Singapore. All Rights Reserved.  Layer Thickness Filling volume and vial type Drying time 10 mm – approx. 24 hours drying time 20 mm – approx. 48-60 hours drying time Pre-freezing takes place in: In vials, dishes ( = static pre-freezing ) in cold air (deep freezer) or with contact cold (directly on shelves of the freeze dryer). At walls of rotating flasks ( dynamic pre-freezing ), the liquid is frozen onto the inner wall of the vessel through constant rotation (shell- or spin-freezing) © Copyright National University of Singapore. All Rights Reserved.  Common Urban Myths More lyoprotectant is better for the freeze dried product. Lyoprotectants stabilize by replacing water but melting point is reached at lower temperature (e.g., -39°C instead of 0°C) – deeper cooling required. Deep vacuum improves the drying. Condenser capacity is limited and the generation of a high gas volume at once leads to unstable vacuum. © Copyright National University of Singapore. All Rights Reserved.  Excipients © Copyright National University of Singapore. All Rights Reserved.  Freeze Drying Changes in the product microenvironment © Copyright National University of Singapore. All Rights Reserved. Source: Merivaara et al. 2021, J. Control. Rel. (https://doi.org/10.1016/j.jconrel.2021.06.042)  Steps and Effects Freezing Shift in pH and high osmotic pressure during freezing increase the risk of agglomeration. Phosphate buffer Histidine buffer © Copyright National University of Singapore. All Rights Reserved. Zuo et al. 2021, J Control Rel (https://doi.org/10.1016/j.jconrel.2021.06.038) Source: Kohle et al. 2009, Biotechnol. Prog. (https://doi.org/10.1002/btpr.377)  Steps and Effects Annealing Ice crystal size affects the drying rate, mostly due to the heterogeneity after rapid freezing and reduced mass transfer. Annealing can be achieved by operating in temperature cycles below Tg’ and is used to increase ice crystal size. Crystal growth also reduces the stability of biological samples, hence annealing promotes rapid drying at the expense of a more stressed product. © Copyright National University of Singapore. All Rights Reserved. Source: Searles et al. 2001, J. Pharm. Sci. (https://doi.org/10.1002/jps.1040)  Cryoprotectants Inhibition of crystal growth Glycerol DMSO Steric stabilizer and mechanical support Surfactants (e.g., polysorbate, Cremophor®) Polyethylene glycol Polyvinyl pyrrolidone Dextran Albumin © Copyright National University of Singapore. All Rights Reserved.  Steps and Effects Drying Sublimation effectively removes binding partners of the freeze-dried product. Example shows an assumed mechanism of water replacement for phospholipid headgroups in liposomes. Hydrophilic molecules (sugars and sugar alcohols) replace the binding partner water. © Copyright National University of Singapore. All Rights Reserved. Source: Chen et al. 2009, J. Control. Rel. (https://doi.org/10.1016/j.jconrel.2009.10.024)  Lyoprotectants Glass transition temperature of a freeze-concentrated solution (Tg’). Temperature must always remain below Tg’ to avoid melting of the sample. Rule of thumb: Product temperature should remain 2-3°C below Tg’ to avoid product collapse. © Copyright National University of Singapore. All Rights Reserved. Source: Meng-Lund et al. 2019, Int. J. Pharm. (https://doi.org/10.1016/j.ijpharm.2019.05.065)  Formulation Science Biosimilars Biosimilars should use the same dosage form and the excipients are widely identical. Small differences in certain excipients (e.g., human serum albumin) may not preclude a finding of biosimilarity if data and information provided show that the proposed product is highly similar to the reference product. © Copyright National University of Singapore. All Rights Reserved.  Process Analytical Technology © Copyright National University of Singapore. All Rights Reserved.  Process Analytical Technologies Measurement techniques that are integrated into a process to ensure so-called process monitoring. Important basis for quality monitoring in complex manufacturing environments. Where the highest quality is needed, PAT is usually indispensable today. © Copyright National University of Singapore. All Rights Reserved.  Steve Jobs and the MacFactory Manufacture of medicines requires high quality standards. For processes without "feedback loops" errors remain undetected. Identify the problem at your doorstep © Copyright National University of Singapore. All Rights Reserved.  PAT = Feedback Process Analytical Technology is used for the continuous monitoring of a manufacturing process. It assumes that certain process parameters indicate whether the process provides the desired product quality. Captures an important process parameter. High measuring speed. Robust and long-running instruments with long maintenance intervals. © Copyright National University of Singapore. All Rights Reserved.  Process understanding PAT is not only used for monitoring but also for understanding the process. Important objectives are: Understanding all processes that influence quality. Predicting quality issues. Respond before issues impact quality. © Copyright National University of Singapore. All Rights Reserved.  PAT Freezing point Temperature and conductivity curve The electrical conductivity of the product Freezing Point increases dramatically, when changing from solid to liquid phase. Stopper The freezing point can be indicated by Sensor recording temperature + resistivity Product curve. © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Single-Vial PAT Electrical resistance Monitoring electrical resistance is suitable to detect melting. The electrical resistance of products increases, when changing from liquid to solid phase. The freezing point can be indicated by recording temperature + electrical resistance. © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Single-Vial PAT Electrical resistance Product LyoRx= temperture Resistivity Resistivity and temperature curves meet at the melting point. Too aggressive heating during drying probably causes the melting. © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Single-Vial PAT Temperature © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Single-Vial PAT Handling single-vial sensors Conventional Sensor Unit Conventional wired sensors cause considerable handling problems (“cable spaghetti”) Accuracy max. ±1K Wireless Sensor Unit Simply wireless: WTMplus Exact sensor positioning Improved accuracy ±0.5K © Copyright National University of Singapore. All Rights Reserved.  Single-Vial or Batch PAT LyoBalance Function principle Electromagnetic force compensation Weight determination Via gripping arm, lifted in customer defined time cycles  Temperatures of -40°C to +40°C Application range  Resolution up to 30g vial weight: 0,001g  Integrated in LSCplus controller  weight loss / drying rate documented in process graphics Advantages  Direct measurement (no use of indirect parameter)  Can be placed onto every shelf position © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Batch PAT Vaccum Higher vacuum increases the sublimation rate but also requires a more rapid recondensation to reduce volume. Changes in the vacuum stability indicate issues with the mass transfer © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Batch PAT Mass spectrometry Tool for troubleshooting or method development rather than process monitoring. Measures gas composition (e.g., water content to determine the progress of freeze drying). More information on the effectiveness of drying at various temperatures. © Copyright National University of Singapore. All Rights Reserved.  Batch PAT Pressure Rise Test © Copyright National University of Singapore. All Rights Reserved.  Batch PAT Pressure Rise Test Used for determination of process end. Pressure measurement inside drying chamber: comparison actual values vs. empty system Result is an "indication", no exact measurement "intermediate" valve closed for some seconds, display of vacuum increase © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  PAT summary Single-vial PAT: Batch PAT: Product temperature probes Vacuum sensors indicate measure temperature issues with mass transfer. changes. Pressure rise test is testing Resistance probe measure for residual water. conductivity changes. Mass spectrometry is testing Microbalance system gas composition. measure mass loss/transfer. … … © Copyright National University of Singapore. All Rights Reserved.  Check Process (without “fancy” equipment) Manual Pressure Rise Test (“Needle jump test”) Close valve manually and watch the pressure carefully. Increase in pressure (“jumping needle”) indicates incomplete drying. © Copyright National University of Singapore. All Rights Reserved. 45  Quality control (without “fancy” equipment) Finger test Grinding the dry sample, no "crumbs" should be sensed. A well-dried sample feels soft. Visual appearance Good appearance of the "cake" No melting (collapse) Redispersion Fast redispersion of the product without sonication or vortexing (drug products are commonly redispersed in hospitals and not labs) Source: Mohammed, Gosselin, Cournoyer 2021, American Pharmaceut Rev (Identifying Collapse in Freeze Dried Products Via NIR 46Spectroscopy) © Copyright National University of Singapore. All Rights Reserved. Martin Christ GmbH  Freeze drying process No Step Explanation Example Determination of the - DSC freezing point Teutectic point = -3°C 1 (eutectic point or glass - Freeze drying microscope - Literature transition temperature) Sample temperature will be defined according to vapour TMain drying = -3°C -10°C = -13°C 2 Setting of the drying vacuum pressure curve: TMain drying  TFreezing  pMain drying = 1.980mbar  TEutectic point. -10°C Evaporation without too-deep vaccum © Copyright National University of Singapore. All Rights Reserved.  Freeze Drying Process No Step / procedure Explanation Example At a filling hight of 0.7 mm in the vials, primary drying time Layer thickness of 24 h before increasing 3 Setting of the drying time  10 mm = 24 h temperature for secondary  20 mm = >24-72 h drying. Manual pressure rise test can be performed on almost every freeze dryer. Reachable vacuum depend Reduce vacuum to minimum on ice condenser (after pressure rise test) and temperature: 4 Initiating secondary drying observe for 5 min if the -55°C condenser: pressure remains stable. approx. 0.05 mbar -85°C condenser: approx.0.005 mbar © Copyright National University of Singapore. All Rights Reserved.  From R&D to Production Production Freeze Lab Freeze Dryers Pilot Freeze Dryers Dryers  2 to 24 kg  6 to 16 kg  25 to 500 kg  Routine-/Advanced  unit design similar to  1 to 40 m² shelf area  Application-oriented production units  Autoloading Systems accessories  Comprehensive range  Project Engineering of PAT-tools including System Integration and Qualification (IQ/OQ) © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Summary Freeze drying is a mild drying process through sublimation of water. Freeze dryers maintain the temperature through their condenser or active cooling and apply samples to reduced pressure. Risks are associated with freeze concentration and the related changes in the chemical or physical microenvironment. Increasing temperature can lead to melting. PAT enables improved process monitoring and involves among others conductivity, temperature and pressure monitoring. © Copyright National University of Singapore. All Rights Reserved.  Questions in PR5217 Answers provided twice a week © Copyright National University of Singapore. All Rights Reserved.  THANK YOU © Copyright National University of Singapore. All Rights Reserved.  Project Integration © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH  Project Integration © Copyright National University of Singapore. All Rights Reserved. Source: Martin Christ GmbH