|
Term
|
Description
|
| Manifold Freeze Drying |
Drying in containers attached to a manifold such that the product receives heat from the room |
| Manometric Temperature Measurement |
(MTM) A procedure to measure the product temperature at the sublimation interface during primary drying by quickly isolating the freeze-drying chamber from the condenser for a short time and by subsequent analysis of the pressure rise during this period. Allows the computation of the resistivity of the freeze dried section of the cake |
| Mass |
The amount of matter in a body |
| Matrix |
A frozen matrix: A system of ice crystal (the ice phase) and other solids that characterized the frozen product. A freeze dried matrix: a cake structure created by and retained after freeze drying. |
| Mean Free Path |
The average distance a molecule can travel as a gas before it collides with another molecule |
| Mechanical Vacuum Pump |
The mechanical system most often employed to lower the pressure in the chamber to facilitate freeze drying |
| Meltback |
One of a number of terms traditionally employed to describe "collapse" or a collapsed product |
| Melting |
The process of changing from a solid to a liquid |
| Melting Point |
The temperature at which a crystalline solid and a liquid can exist in equilibrium at standard atmospheric pressure. The temperature at which a solid changes into a liquid |
| Melting Temperature |
The temperature where mobile water first becomes evident in a frozen system (either by casual observation or by instrumental determination) |
| Microbar |
A unit of pressure used in the freeze drying or lyophilization process. One microbar (a pressure of one millionth of a bar) equals 0.75 millitorr |
| Micron |
(See Torr). A unit of pressure used in the freeze drying/lyophilization process. One micron (the pressure that supports a column of mercury to one millionth of a meter high) is also equal to 1.33 microbar |
| N.I.S.T |
National Institute of Standards and Technology. A US agency, formerly the National Bureau of Standards (NBS) |
| Non-Aqueous Freeze Drying |
Any freeze drying process in which the solvent or solvent system contains no water, but in which the solvent can be crystallized by cooling and vacuum allows sublimation. |
| Noncondensable |
Gases such as hydrogen, helium, neon, nitrogen, oxygen and argon. They may be drawn into a vacuum system through leaks. Their presence may reduce the operating efficiency of the freeze dryer |
| NPT |
National Pipe Thread. May be FNPT for female national pipe thread or MNPT for male national pipe thread |
| Nucleation |
The initiation of the crystallization process. Nucleation may be heterogeneous or homogenous |
| Oil Mist Filter |
(Oil Mist Eliminator). A filter attached to the discharge port of an oil-sealed rotary vane pump to eliminate most of the aerosol and often times, return it to the pump |
| Oil Sealed Rotary Vane Vacuum Pump |
A standard type of mechanical vacuum pump used in a majority of freeze drying application |
| Oil Separator |
Separates the oil from the compressor discharge gas and returns the oil through the oil float trap and piping to the compressor crankcase |
| On/Off Control |
Control of temperature about a set point by turning the output full on below set point and full off above set point in the heat mode (and vice versa in the cooling mode) |
| Operating Variables |
All factors, including control parameters that may potentially affect process state of control and/or fitness for use of the end product |
| Operational Qualification |
(OQ) Documented verification that the system or subsystem performs as intended through all anticipated operating ranges |
| Overshoot |
Condition where temperature exceeds set point due to initial power up or process changes |
| Parenteral Drug |
Injected, infused or implanted medicinal product |
| Part Aqueous Freeze Drying |
Any freeze drying or lyophilization in which the solvent system is partly aqueous (i.e. contains water, among other solvents) |
| Partial Pressure |
In a mixture of gases or vapors or both, the pressure exerted by any one of the species independently of the others |
| Phase Diagram |
A graphical representation that describes the physical state of a system as a function of composition and temperature |
| Phase Transition |
A change of physical state which can include, i.e.., crystallization, melting and dissolution (each of which is called a first order transition). Second order phase transitions include glass transitions (conversions from i.e. brittle to elastic amorphous states to viscous fluid states) |
| PID |
Proportional Integral Derivative. Type of control incorporating the three control strategies. |
| Pirani Gauge |
An instrument, named after the inventor, for measuring total gas pressure in a vacuum system in which the temperature of a heated filament (or the power to heat the filament) allows the quantification of the pressure. Commonly used in freeze dryers but provides erroneously high readings in the presence of water |
| Pressure |
Force per unit area |
| Primary Drying |
That part of the freeze drying process that involves the sublimation of ice or that part of the freeze drying process allocated to the sublimation of ice |
| Process Analytical Technology |
(PAT) A mechanism to design, analyze, and control pharmaceutical manufacturing processes through the measurement of critical process parameters. |
| Process Development |
Establishing evidence that all process control parameters and all control parameter ranges are validated and optimized |
| Process Validation |
The documentation of evidence that a process does what it purports to do |
| Process Variable |
A system element to be regulated, such as time, temperature, pressure, relative humidity…. |
| Product |
Material prepared for freezing and/or freeze drying or the same material after freezing and freeze drying |
| Proportional Band |
Span of temperature about the set point where time proportional control action takes place |
| Prospective Validation |
Establishing documented evidence that a system does what is purports to do based on a preplanned protocol |
| Protocol Supplement |
A document that explains a change to the original protocol, including reasons for its need |
| Proven Acceptable Range |
(PAR)All values of a given control parameter that fall between proven high and low worst-case conditions |
| PSI |
Pounds per Square Inch |
| Puffing |
One of a number of terms applied to describe freeze drying in which product exhibits a gross expansion as it freeze drys, generally at too high a freeze drying temperature and more specifically abov4e a threshold collapse temperature). |