A pharmacist turns detective

[Guest guest]

In The 'Prescriber' magazine this month, a pharmacist has

pointed out that a patient had complained that their packet of levothyroxine

tablets didn't work like their usual brand - so she turned to being a detective

to find out why. She sent the tablets of thyroxine off to the makers to ask for

them to be analysed. Eventually, the results came back. Manufacturers have to

keep back samples from the beginning, the middle and the end of each batch so

they can compare a particular sample with the rest of the batch.

The sample tablets from the beginning of the batch of her

patient's tablets came from contained 101,7ug levothyroxine - the sample from

the middle contained 101.5ug and the sample from the end 99.9ug - the

acceptable range being 92 - 110ug per tablet. To her surprise, her patient's

tablets contained only 81.5ug levothyroxine per tablet, a reduction of nearly

20%, which neatly explained why she had felt the symptoms of hypothyroidism.

The obvious conclusion for this was not that the

levothyroxine hadn't been put in the tablets in the first place, but that it

had, and had then degraded. Is this possible?

Yes it is!

First, Sherlock Holmes says that when you have excluded the

impossible, what remains, however improbable, must be true.

Second, the pharmacist found an interesting case report of a

patient who stored his levothyroxine tablets in a screw of newspaper and experienced

a lack of effect, a problem that was not observed when the tablets were stored

in the correct amber glass bottle.

In that case, the tablets were not tested for potency but

levothyroxine is notoriously unstable stuff, particularly when exposed to

conditions of high humidity, high temperature and light.

So, knowing this, where do we keep our medication? In

the medicine cabinet, in the bathroom. The most warm, humid room in the whole

house.

Learn a lesson from this folks.

Luv - Sheila