The reason that IPAC-RS would like to see a change of the draft guidances and the replacement with the PTIT is that because the PTIT is a more powerful test. It uses the data collected in a more efficient way and it does not have this penalty with increased testing. Another main reason is that many of the OINDPs cannot routinely meet expectations in the draft guidances, and this is demonstrated by the fact that for many products, there have been approved exceptions and deviations from the test and acceptance criteria in the published guidances.
The statistical design of the PTIT is built on previous work, mainly by Dr. Walter Hauck, but also work performed within the pharmacopoeias and especially the Japanese Pharmacopoeia, but it also incorporates some features of the FDA draft guidance test. The acceptance criteria were designed to match or exceed the statistical consumer protection implied by the published guidances.
Briefly, the batch quality definition is based on coverage, which is the proportion of doses in the batch are within a set target interval. This means that batches having the same coverage of a given target interval are