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Prescribing
Storage temperatures
CPD
The Society
The Journal
Letters to the Editor
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Storage temperatures
Confusion remains over drug stability to heat
From Mr C. Polwart, MRPharmS
The news article “Hot weather no risk to medicine stocks” (PJ,
16 August, p195) was misleading and provided little valuable help to
pharmacists, leaving more questions unanswered than it actually addressed.
It is hardly helpful to reassure pharmacists that unnamed pharmaceutics
experts say “most medicines are tested to meet the requirements
of the International Conference on Harmonisation of Technical Requirements
for Registration of Pharmaceuticals for Human Use” (ICH). Most
pharmacists will already be aware that there is unlikely to be any major
effect from short-term exposure to temperatures greater than 25C for
most of their stock. The problem remains that there will be a minority
of stock that can not withstand this exposure.
The difficulty for pharmacists is identifying which drugs will be affected
in order that they can be protected in the first place, or if necessary
destroyed. The ICH website provides details regarding the testing but
no indication of which products have been tested, and as the Association
of the British Pharmaceutical Industry spokeswoman points out, medicines
should be stored as listed in their product licence. Are we to call the
manufacturer for every item stocked in our pharmacies to check if they
have stability data at higher temperatures? Even if manufacturers do
have data they will always be at pains to stress that the use of a product
that has been stored outside its licensed storage conditions is no longer
licensed and the user takes legal responsibility.
Although the ICH standard dictates that refrigerator lines should be
able to withstand exposure at 25C for six months a brief review of data
held on the Guy’s and St Thomas’ NHS Refrigeration Database,
suggests that for many refrigerated products this is not the case, which
leads me to wonder what proportion of tablets tested to ICH also fail
to meet the standard. Is there an easy way to identify which products
fail to meet the ICH standard?
Much of the article concentrated on the storage of tablets and topical
products, it failed to consider the storage of liquids and injections,
where the risk of hydrolysis is much greater and where the effects of
temperature accelerate the reaction. Additionally temperatures above
30C, which have been recorded for a number of days in some parts of the
country, provide ideal conditions for incubation of microbiological contamination
in opened containers of liquids and suspensions.
Is it now time for the Society’s Code of Ethics to incorporate
a requirement for validation of temperatures for drugs stored at room
temperature as well as for drugs stored in refrigerators, rather than
the current statement? Such a requirement is necessary for pharmaceutical
wholesalers, licensed through the MHRA.1 There is an easier way for pharmacies
to avoid concerns about drug storage — install air conditioning.
Many pharmacies already have air conditioning and many others will be
able to maintain temperatures below 30C throughout the year without the
need to install air conditioning. For the remainder, where temperatures
regularly rise above 25C and often peak at over 30C, how sure can we
be that every one of the products on our shelves remains within its limits
throughout its use? Or will it be legitimate to cite the news article
in The Journal, as evidence that the products are safe when exposed to
temperatures of 40C?
Perhaps the most burning question that arises from this article is why
the PJ chose to publish an article entitled “Hot weather no risk
to medicine stocks” the same week that the Society published a
press release to patients warning them “the summer heat could damage
their medicines”? Who are we to believe — the PJ or the Society?
Calum Polwart
Durham
References
1. Taylor J. Recommendations on the control and monitoring of storage
and transportation temperatures of medicinal products. Pharm J 2001;267:128–31
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