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kilomentor | 19 December, 2008 19:34
A pharmaceutical process that has been scaled-up is monitored using the results of in-process controls. These are tests that either conform or do not conform to a preset standard. If the test conforms, the operators proceed to the next instruction of the batch process, but if the result is nonconforming, the result is reported to the manager who decides what action to take next. For an in-process test, the actions to be taken are characteristically thought out in advance. If there is no possible corrective action for an out of specification result, the test is not a proper in-process test but rather just a datum that may be part of the analysis of the result when the final outcome is known.
When a process has been optimized it is taken for granted that it will operate within its control limits and no more testing than the in process ones will be required to guide the operators to a successful result.
Pilot Plant Experiments and Forensic Testing.
Although the chemical plant or kilo lab process can be modelled using a laboratory scale procedure, it cannot be optimized without results from representative samples from the scaled up process taken at critical decision points in the process.
The pilot plant runs are still experiments even if the equipment is handled by personnel who are not research chemists. Although the chemist may think that (s)he understands completely the experimental reaction and subsequent purifications steps being scaled up, at least for all practical purposes, this isat least immodest and usually foolish. The experimenter is wisest who anticipates the most potential problems and collects useful samples at every convenient sampling point every time the process is executed on scale. Taking many more samples than simply those, which are mandatory for in-process control. These extra samples we will call forensic samples because they are very often only analyzed when a result is unsatisfactory. When the result is unexpectedly disappointing in any respect. these samples can provide the evidence useful to determine what went wrong and how to correct it.
Forensic samples are carefully stored so they will not deteriorate. They are in addition to the process control samples Forensic samples are not analyzed during the time the process is running, but are for retrospective testing by the process chemists.
There is only one downside to the collection of forensic. If the process runs perfectly and gives a product of the exact same quality as the laboratory samples but with a lower yield, the question may arises whether taking samples might be predominantly responsible for the reduced yield. Most often the size of the samples or the mechanical losses that can occur when taking forensic samples cannot explain a noticeable reduced yield on scale. The samples are typically just not large enough compared to the size of the process.
In every other outcome the sampling will provide a great chance of understanding what has caused the deviation from the desired result.| « | December 2008 | » | ||||
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