Akers et al discuss the equation for estimating the F0 value in a steam sterilizer. This can help validate the sterilization of parenteral solutions as part of good manufacturing practices.


Test set-up: A thermocouple or other temperature measuring devices is embedded within a sample undergoing sterilization. The temperature is recorded constantly throughout the sterilization cycle.


F0 in minutes =

= (time interval for monitoring in minutes) * SUM(10^(((temperature recorded for time interval) - 121) / (Z value)))



• The Z value is the number of degrees Celsius associated with a decrease of 1 LOG10 decrease in organisms. This usually is 10°C.

• 121°C is the maximum temperature in the standard steam sterilizer.



• For large volume parenterals the target F0 for the process is usually > 8 minutes.

• The target F0 for a process depends on (a) resistance of micro-organism to thermal sterilization, (b) initial organism load, (c) desired level of organisms after sterilization.


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