WHO publishes New Version of the Draft on "Hold-Time" Studies

The 2nd revision for comment was published already in February this year (we reported). Now, a 3rd version is available - also for comment. The document describes the design of hold-time studies for the determination of time limits which have to be determined according to the generally applicable intermediate and bulk products. This should avoid that the storage of intermediate or bulk products from having any negative influence on their quality or the quality of a finished before processing to the next stage.

Chapter 2 which defines what intermediate and bulk products are has been added. It is now explicitly pointed out that hold-time investigations are part of the process validation. In turn, the reference to retrospective observation has been removed from the current version as well as - fortunately - the incomprehensible paragraph on the ‚most probable / worst case approach'.

Still, the different stages of production are explained with the example of solid forms. A flow chart for better understanding has been newly added.

The second part of the last chapter has been completely revised. In the second version, it contained proposals for hold-times of different process materials (in contradiction with the statement according to which data have to be collected for the determination). The quite vague information about cumulated hold-times has also been removed. Instead, the new version now contains a table with proposals of stages and respective tests that may be considered to certain study times.

Revision 3 of the draft can be found in the Members Area.