Reformulation of thyroxine tablets is not as easy as it looks

[diogenes]

The makers of Euthyrox T4 tablets decided to reformulate and put outa paper justifying this as being accurate as regards bioequivalence, The article is as below. I know well that many posters on TUK complain about practical non-equivalence of reformulated tablets. We have submitted a Letter to the Editor regarding the best mathematical/statistical way of analysing this data. When the data is properly statstically handled, the comparison at the individual level shows far from a close relationship (almost random). This should help other reformulators to consider the optimum statistical analysis in producing their results. The obvious solution is to keep to one formulation by one producer if at all possible.

Curr Med Res Opin. 2017 Feb;33(2):169-174. doi: 10.1080/03007995.2016.1246434. Epub 2016 Oct 21.

New levothyroxine formulation meeting 95-105% specification over the whole shelf-life: results from two pharmacokinetic trials.

[helvella]

I am holding my breath waiting to read your letter!

In that paper, it says:

The new formulation will enable patients to receive a dose fine tuned to their medical needs, contributing to improved safety in the use of L-T4.

ncbi.nlm.nih.gov/pubmed/277...

I cannot see what they could do to the product to improve the fine tuning of the dose that was not possible with the (claimed) bio-equivalent previous formulation.

If the products are 100% bio-equivalent, there would be absolutely NO change in how well tuned the dose.

It is only if they are NOT bio-equivalent that there would be any reason to mention the fine tuning of the dose.

[Nanaedake]

Oh, how I wish the NHS would recognise the need to stick to one formulation instead of dispensaries being allowed to switch 'brand' at the whim of the contracted pharmaceutical supplier!

I don't object to generics and I think the cost of essential drugs needs to be kept to a minimum. However, historically, different levothyroxines have been found to be unequivalent in potency effect once ingested.

[hjh88]

That’s so interesting. I just tried some Euthyrox last month for the first time, only for a couple of weeks, and became horribly hypo very quickly. I’d always read on here that folk got on with it quite well generally so was surprised when I didn’t but a reformulation would explain that. Such a shame as it seems to be a bit of a go to for those needing to self medicate!

[jgelliss]

Diogenes thank you for your heads up posts as always . It's very appreciated . This is unbelievable . The only thing that thyroid companies ought to do is to remove fillers that we can do without and dyes from the thyroid meds.

If it's Not Broke . Why Fix. The only reason I can read into their reformulating is to save more money for themselves . In my book that called *Greed*.I don't believe for one second that their fix is for our benefits . I'm very worried that when one thyroid brand changes the other brands will follow suit too. This happened all across with the NDT brands too. I for one I smell a rat . I don't want to be the lab rat for the thyroid companies. I hope something can be done to stop this from happening .

[Herhat]

I had been taking the original formulation of Euthyrox with the lactose base for over 10 years, but since I started on the new citric acid formulation in November 2019 I have not felt the same. My thyroid levels has been checked and are corect, but I just feel constantly washed out, exhausted. My specialist just tells me to give it time.