A letter to the British Medical Journal in 1978 said:
SIR, -- We write to suggest that thyroid extract (Thyroid, BP) be removed from the British Pharmacopoeia and that its manufacture be abolished.
We continue to see patients who have been diagnosed as having myxoedema and who are being treated with apparently adequate doses of thyroid extract but who are clinically and biochemically hypothyroid. They have subsequently responded to thyroxine.
Although it is never to be certain that drugs prescribed are being taken, there is good evidence the potency of thyroid extract is variable and its shelf-life dated. As both active constituents. thyroxine and triiodothyronine, have been available for many years we see no reason for the retention of thyroid extract, which we consider to be dangerous.
W van't Hoff G M Besser
R Hoffenberg J S Staffurth
D R London David C Anderson
R Hall J Jenkins
G F Joplin R L Himsworth
Br Med J 1978; 2 doi: doi.org/10.1136/bmj.2.6131.... (Published 15 July 1978) Cite this as: Br Med J 1978;2:200
The letter to the BMJ, which appears to have hammered the nail into the coffin of Thyroid BP, puts forward three arguments against the product:
It is variable.
That is fundamentally a manufacturing issue. We have seen remarkable variation across all thyroid hormone products even just in this century. We have also seen remarkable improvements in the ability to assay the products.
It is shelf-life dated.
This somewhat odd statement. In these days of advanced packaging technology, is there any reason to think the shelf-life is any more questionable than that of levothyroxine?
Thyroxine and triiodothyronine, have been available for many years.
Yes, I suppose they had, even then. And now, theoretically, they have been available for even more years! But effectively triiodothyronine (also known as liothyronine) is rapidly becoming unavailable. So, unless something is done to make it available again, this argument disappears.
Arguments not put forward:
Patients don’t need any T3/liothyronine medicines;
Patients prefer levothyroxine;
We tried increasing the dose of Thyroid, BP but that didn’t help;
[Note: So far as I can tell, the UK Thyroid, BP product was half the potency of the USA products. Some papers seem not to recognise this important difference.]