E-DRUG: Stability and administration of drugs at very low temperature (2)
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Dear colleagues
Medicines should be stored as recommended on the label. There are a number that
are unstable when stored at a cooler temperature than is recommended.
Some injectable solutions precipitate at low temperatures, such as fluorouracil
50mg/mL which is labelled 'Store between 8degC and 25degC' or similar. It
should not even be stored in a refrigerator. For some injectables,
reconstitution may be possible, but only if permitted by the prescribing
information because high temperature may lead to chemical instability.
Many insulins crystallize below 2degC and cannot be reconstituted into the slow
release form they were intended to be. Their instructions include 'Protect from
freezing' or similar.
While many (most) biological medicines are recommended for storage in a
refrigerator, some are unstable when frozen, such as heparin, trastuzumab and
erythropoietin. Read the label!
But this does not help pharmacists who have limited storage facilities. And
Seyfu has a point when he notes that IV fluids at low temperature may be
unhelpful for sick people. In the latter case, the pharmacist should notify the
physician of the problem.
Susan Walters
Australia
susanw@netspeed.com.au
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