Bill 2008-09-19 23:40:18
In general, some drugs say they need to be refrigerated and/or stored at
What happens if this is not done?
Do some drugs loose their potency?
Or is it a “packaging thing” and the gelatin capsules will tend to “melt” if
placed in a high temperature situation, but the drug itself is fine?
Gregory poon 2008-09-19 23:40:33
Do you have some specific drug in mind? Generally speaking, drugs and
substances used in making their dosage form degrade in some sense (e.g.,
in terms a loss of potency) at some measurable rate, and this rate
depends on temperature. In most cases, the higher the temperature, the
higher the rate. The stated expiry assumes that the drug is being
stored under the specified conditions. So the expiry stated on a vial
of insulin is only valid when it is refrigerated at 4 C. If it is
stored at room temperature, it will degrade (in this case lose potency)
in (at most) 28 days. If it’s subjected to greater heat, it’ll go even
more quickly. If it’s hot enough, the insulin will become almost
instantly useless, as well as dangerous: heat-denatured insulin
aggregate and precipitate out of solution (i.e., becomes cloudy), which
is extremely dangerous if it is to be used intravenously.
As you alluded to with the gelatin capsule example, drugs and dosage
forms also degrade in other ways, but that is not generally related to
the stated expiry date.
Rod 2008-09-19 23:41:03
Having read the OP, I was reminded of the threads about levothyroxine.
Though the instructions state that it should not be stored above 25 C,
even the manufacturers/distributors are unable or unwilling to provide
information of what the effects would be of storing at, say, 30 C.
I doubt that every store room of every pharmacy is air-conditioned all
day and all night, so I strongly suspect that at least some is stored
above 25 C for extended periods prior to dispensing.
In this case, I am wondering exactly what the breakdown products would be.
Sipho 2008-09-19 23:41:08
In addition to answer your question there are some active ingredients
that are unstable in heat and therefore a certain temperatures e.g.
below 25 C are essential for the active to remain in a stable state.
Some active ingredits can also change form if placed in in very high
temperatures and then cooled again. For example certain syrups can
crystalize after being heated above 25 C and then being cooled. This
might lead to some drug content being lost.
Gregory poon 2008-09-19 23:41:11
Stability testing is usually done under accelerated conditions,
typically high temperatures, and then extrapolated back to the intended
storage temperature (say between 15 to 25 C). The expiry date given on
the packaging is therefore calculated for that storage temperature. The
devil is in the details, but generally speaking, storage at some higher
temperature will accelerate expiry (for example in terms of loss of
“potency”). Every drug is its own molecule; the identity of the
breakdown products will depend on the particular item in question.
A responsible pharmacy will have reasonable temperature controls in the
dispensary. It’s not just about being air-conditioned all day and all
night, but also having adequate heating in very cold weather.