Thyroxine, also known as T4 or levothyroxine, is indicated for thyroid hormone deficiency and to suppress thyrotropin (TSH)-responsive tumours.

Storage conditions can make it challenging to manage the administration of thyroxine to patients within healthcare facilities, as doses may be inadvertently missed due to the medicine being stored out of sight.

The Product Information for both available brands, Oroxine® and Eutroxsig®, states:

“Store at 2oC to 8oC. Refrigerate. Do not freeze…
A single blister strip can be removed from the carton and stored below 25oC for up to 14 days (two weeks). After 14 days (two weeks) of storage below 25oC, discard any remaining tablets.”

Both are packaged in boxes of 200 tablets, with doses of 50mcg and 75mcg presented in eight blister strips of 25 tablets, and 100mcg and 200mcg in ten strips of 20 tablets each. If a single blister strip is removed from the carton to store at room temperature and a patient takes one tablet daily, the expiry becomes limited to 14 days, resulting in wastage of up to 11 tablets.

A solution for this dilemma is to cut the blister strip, ensuring that no more than 14 days’ supply are stored at room temperature. However, hospital policy should be considered with regard to recording the batch number and expiry date on the section of the blister strip that does not have this information printed on it.

As the prescribed dose of thyroxine is highly variable, the quantity of tablets contained in one whole blister strip may not reflect the number of dosing days, such that a strip of 25 tablets will last for 50 days at a daily dose of ½ a tablet, and 16½ days at 1½ tablets. Hence, blister strips may need to be cut in different configurations.

Ideally, the whole box of thyroxine tablets should be stored in the fridge, and each tablet removed from the original packaging at the time of administration.

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