With the proviso that you are not operating in one of the high
temperature climate zones the answer is quite simple. Read ICH
guidance but the bottom line is that the real justification is
stability at the real storage conditions. Accelerated conditions
allow you to claim a real storage shelf life that is longer than the
accelerated conditions.
CPMP states
"At the accelerated storage condition, a minimum of three points,
including the initial and final
time points (e.g., 0, 3, and 6 months), from a 6-month study is
recommended. Where an
expectation (based on development experience) exists that results
from accelerated testing are
likely to approach significant change criteria, increased testing
should be conducted either by
adding samples at the final time point or by including a fourth time
point in the study design.
When testing at the intermediate storage condition is called for as a
result of significant
change at the accelerated storage condition, a minimum of four time
points, including the
initial and final time points (e.g., 0, 6, 9, 12 months), from a
12-month study is recommended"
Malcolm Ross
Generapharm-training and consultancy
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