That article is from 2004 so a bit out of date but the potency issue is the problem with expired thyroxine. My thyroxine (Eutroxsig) states to be stored at 2°C to 8°C but my expiry date is still 12 months from when I picked up the prescription.
I live in Australia and I found the potency of the medication reduced drastically when not refridgerated and symptoms of hypothyroidism showed up badly again.
This is some info from Australian Prescriber - Taking Care Of Thyroxine...
"Thyroxine is stable in dry air, but unstable in the presence of light, heat and humidity. In some cases overseas, thyroxine tablets have been unstable even at room temperature, and storage temperatures of 8°C to 15°C were required to maintain potency. In the USA, the Food and Drug Administration has determined that stability and potency problems with oral thyroxine preparations could potentially have adverse effects on health. It is therefore very important that thyroxine tablets should be kept in their original container and stored out of sunlight in a cool dry place.1
The expiry date for Australian manufactured thyroxine tablets is one year from the date of manufacture. There are 200 tablets in a bottle, so it is possible that patients on half tablet doses will not finish the bottle before the stock expires. The expiry date should be emphasised to the patient to ensure they do not continue taking a thyroxine preparation that may be waning in potency. However, stock with a shelf-life of 18 months will soon be available. This formulation will require refrigeration at all times."
Thank you, very helpful indeed :)
I can't imagine any adverse effects. Note the info in this link. It is a response to a similar question related to Armour Thyroid.
http://www.medhelp.org/posts/Thyroid-Disorders/Expired-Armour-Thyroid/show/2720988