The purpose of the stability study is to establish, based on testing a minimum
of the number of batches specifi ed in section 2.1.3, unless otherwise
justifi ed and authorized, of the API and evaluating the stability information
(including, as appropriate, results of the physical, chemical, biological and
microbiological tests), a re-test period applicable to all future batches of the
API manufactured under similar circumstances. The degree of variability of
individual batches affects the confi dence that a future production batch will
remain within specifi cation throughout the assigned re-test period.
The data may show so little degradation and so little variability that it is
apparent from looking at them that the requested re-test period will be
granted. Under these circumstances it is normally unnecessary to go through
the statistical analysis; providing a justifi cation for the omission should be
suffi cient.