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[IPp] Insulin - loss of potency
> In a message dated 4/30/2003 7:10:43 AM Pacific Daylight Time,
> email @ redacted writes:
> > In fact, the labelling says in bold type
> > "THROW NOVOLOG AWAY IF IT HAS BEEN IN TEMPERATURES GREATER THAN 98.6
> > DEGREES F (37 DEGREES C)."
> > So that's why we change the insulin every two days.>>
This is from a letter I received from Eli Lilly and Co. Jan of 1998.
It was in response to a question about Humalog, but it is
generally applicable to all insulin and insulin-analog products.
....While it is agreed that refrigeration should be employed whenever
possible, we have found the loss of biological potency of insulin is
such a slow and gradual process that if one is careful to protect
insulin supplies from extremes of temperature, any decrease of
potency probably will not interfere in any way with the control of
All preparations of insulin are required by law to bear the
instruction on the labels: "Keep in a cold place--avoid freezing."
This is a requirement of the Food and Drug Administration (FDA)
concerning the storage of insulin. As defined in the United States
Pharmacopeia 23, cold specifies storage temperatures between 2 and 8
degrees C (36 to 46 F).
The United States Pharmacopeia Dispensing Information, -Sixteenth
Edition 1996 Advice for the Patient, Volume II has the following
information on insulin storage. "An unopened bottle of insulin should
be refrigerated until needed. It should never be frozen. Remove the
insulin for the refrigerator and allow it to reach room temperature
before injecting. An insulin bottle in use may be kept at room
temperature for up to 1 month. Insulin that has been kept at room
temperature for longer than a month should be thrown away." The USPNF
23 specifications for thermostatically controlled room temperature is
from 59 to 86 degrees F.
At elevated temperatures, insulin has been shown to lose potency.
This loss of potency is accelerated as the temperature increases. For
this reason, as stated earlier, and for reasons of consistent
temperature exposure, it is recommended that refrigeration be
employed whenever possible. As an example, a vial of insulin stored
at 86 F will lose approximately 1.7% of its potency over 30 days. In
contrast, insulin stored in a refrigerator will lose less than 0.1%
of its potency over 30 days.
This last bit is what is of interest. Basically, get it hotter and it
loses strength. Not all at once, but certainly a good percentage over
email @ redacted
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