Thyroid UK
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MHRA Response on t3 licensing

Re: Liothyronine PL 10972/0033

Thank you for your recent enquiry to the Medicines and Healthcare Products Regulatory Agency.

1. The SPC is the approved prescribing information for this product and will include the medical conditions it is licensed for. According to our licensing records, Liothyronine Tablets 20mcg PL 10972/0033 is licensed to treat the following medical conditions (licensed indications):

Liothyronine sodium tablets are qualitatively similar in biological action to thyroxine but the effect develops in a few hours and lasts for 24 to 48 hours after stopping the treatment.

Used for the treatment of coma of myxedema, the management of severe chronic thyroid deficiency and hypothyroid states occurring in the treatment of thyrotoxicosis.

Liothyronine sodium can be used also in the treatment of thyrotoxicosis as an adjunct to carbimazole to prevent sub-clinical hypothyroidism developing during treatment.

Liothyronine sodium may be preferred for treating severe and acute hypothyroid states because of its rapid and more potent effect, but thyroxine sodium is normally the drug of choice for routine replacement therapy.

2. This product was previously licensed as PL 00039/0432 and PL 00004/5032R (Tertroxin Tablets 20mcg). The medical conditions it is licensed for have not changed.

3. The current licence holder is Mercury Pharma Group Limited, Capital House, 85 King Wiliam Street, London EC4N 7BL. The licence has been renewed and is valid indefinitely.

6 Replies

I am glad to see this clear statement:

The SPC is the approved prescribing information for this product and will include the medical conditions it is licensed for.

That means (at face value) that we just have to look at the SPC documents for medicines to find out the licensed conditions. :-) They are mostly available at (along with many Patient Information Leaflets).

Rather less pleasing is the statement the management of severe chronic thyroid deficiency. That is open to many questions. For example, it could be taken to imply that if your TSH isn't enormously high, it is not covered. Severity is not the issue, so far as I am aware. It is whether liothyronine, alone or in combination, makes your better - and is needed to make you better. Some people seem to do well on small doses along with levothyroxine (or desiccated thyroid).


Yes, it is very much open to interpretation and the definitions are beyond loose. Hopefully it will be helpful in countering those who say t3 is not licenced for hypothyroidism at all because it clearly is. However, much will depend on how hypothyroidism is defined, whether by symptoms or TSH.


I agree, home many of us on here will benefit? but what get's me is how much Mercury Pharma Group Limited think they can charge the NHS for this medication, I think that's another reason doctors won't prescribe it, It's criminal......


Some CCG's, in their analysis of what liothyronine is used for state "Liothyronine is available as licensed (and unlicensed) 20 microgram tablets and

unlicensed 5 microgram tablets" or similar.

I am unaware of the precise details but this fact does muddy the water somewhat. Perhaps it relates to the manufacturer.


That statement would appear to be referring to:

a) 20 microgram Mercury Pharma (licensed);

b) 20 microgram (Sanofi Deutschland) Henning Thybon and some other "foreign" makes (unlicensed);

c) 5 microgram Pfizer Cytomel, Perrigo, Mylan, Sigmapharm - all from the USA (unlicensed).

Very odd that they entirely ignore 25 microgram tablets (such as all the USA makes), 50 and 100 microgram, and other possibilities. There again, perhaps not so odd given the authors.


Sorry, should have been clearer. The FOI request was for the licence PL 10972/0033, 20 mcg liothyronine tablets as it is the only tablet licence in the UK

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