Key Definitions
The following are a list of key definitions that will assist
you in the understanding the operation of the CMA, the drying process in a PAT
drying oven for elastomer closures used to protect lyophilized or freeze dried
products.
Dielectric
Constant - The dielectric constant of a material (such as an elastomer
closure) is the ratio of the capacitance of the material to the that found in a
vacuum having the same configuration as that of the material.
FDA Definition of PAT -A system for designing, analyzing and
controlling manufacturing through timely measurements (i.e., during process) of
critical quality and performance attributes of raw and in-process materials and
processes , with the goal of ensuring final product quality. Pharmaceutical
CGMPs September 2000
Freeze Drying -
Freeze drying is a stabilizing process in which there is first crystallization
of the solvent to form a structure in the product and then the amount of
solvent is removed first by sublimation and then by desorption to values that
will no longer support biological growth or chemical reactions. ISL-FD PAT
COMMITTEE - September 4, 2006
Lyophilization - Lyophilization is a stabilizing
process in which the product is first frozen and then the solvent is removed
first by sublimation (primary drying) and then desorption (secondary drying) to
levels that will no longer support biological growth or chemical reactions
Outgassing of Moisture
from A Closure - Outgassing of water vapor occurs from a closure
when the rate of desorption of water vapor from a surface exceeds the rate of
adsorption of water vapor on the closure surface.