We are performing autoclave re qualification (parameters are 121 degree sterilization temperature and holding time is 15 minutes) the autoclave is dedicated for media preparation.
During heat distribution study (empty chamber) results are okay but in penetration study (full load) the sterilization time is not achieved.
We did many trials and get finally 15 minutes sterilization time inside the bottles but the autoclave program is modified to 25 minutes sterilization time.
is this acceptable or we need to re-program our autoclave to 15 minutes and try to verify it.
Reprogram the autoclave and reverify once you have performed an investigation (verify the critical parts…). It is not unusual for ‘older’ autoclaves to miss their acceptance criteria.
This is common. Getting 15 minutes of “Lethality” can take longer hold time. That is why you do engineering studies to determine how long the autoclave cycle should be. Also, there are new requirements for ramp up time. Make sure you follow those as well.
in penetration study, some load can’t reach the expected temperature and thus the the sterilization time is not achieved. So you should find the “cold spot” and change the cycle in order to these spot can achieve the sterilization time and temperature. Using Fo calculation and Bio indications to prove the changed cycle meets all sterilization requirements.