On 30/1/2020 (Over 2 years ago),there was a recall : "Wockhardt UK Ltd. is recalling specific batches of Levothyroxine 100mcg/5ml oral solution from pharmacies and wholesalers as a precautionary measure due to notification of the impurity liothyronine exceeding the specification limit. Liothyronine is a degradant of Levothyroxine and can be used to treat the same conditions but with a faster onset and considered to be more potent than levothyroxine. This potency difference will result in pharmocodynamic effects for patients."
Further Information: "Liothyronine is a breakdown product that is present in Levothyroxine formulations.Liothyronine the synthetic form of the natural thyroid hormone tri-iodothyronine , can itself be used to treat an underactive thyroid but it is generally reserved to treat more severe forms of the condition. This is because liothyronine has a faster onset of action and is also more potent than levothyroxine. These differences in action mean there is a higher risk of adverse effects with increasing liothyronine content and is why this is controlled within strict limits within levothyroxine preparations."
It was Class2 Medicines Recall: Wockhardt UK Ltd, Levothyroxine 100micrograms/5ml Oral Solution EL(20)A/)4, that this came from.
Probably me being thick. Does this mean that levothyroxine liquid actually also contains liothyronine (T3)?
If so, it would follow that when McPammy was overmedicated by Zentiva which contains citric acid anhydrous, as opposed to the citric acid monohydrate most commonly used, (anhydrous is supposed to have a bigger impact), her TSH plummeted, and FT4&FT3 rose.
I probably have the wrong end of the stick. May be everybody knows this?
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For tablets, there is a 1% limit of liothyronine in levothyroxine - a 100 microgram tablet could contain up to 1 microgram of liothyronine.
However, I think the manufacturer would be asking questions way before it reached that level. They have to make it with an allowance for changes after it has been released.
Liothyronine will form, slowly, from pure levothyroxine (or, as is the case for all medicines, levothyroxine with whatever other excipients). Or a tiny bit might be present in the levothyroxine.
I don't think the hydrated/anhydrous issue is at all relevant.
I read something about levo having to generally be within something like 95% and 105 % or similar , of the stated potency. That in itself would make it entirely possible that the potency of even the same brand tablet or, I assume liquid, could be at least 10% different from potency expected, or previously prescribed. Hence, the recent Accord tablets which I think it may have been you and Red Apple had, could be sub potent by 10% lower than a previous batch, but still pass regulations. I know Red Apple felt it was a much more significant discrepancy in sub potency than this.
So you are saying that there is T3 in T4 , but likely as little as a hundredth ?
Levothyroxine tablets in the UK have to be within 90 to 105% of claimed potency - all the way from manufacture to expiry.
We'd hope that they would be well within that range so as to allow some leeway if, for example, they had been stored in less than optimal conditions.
I don't know if liquids have a different potency range.
Trouble is, a lot of people who should know better think of levothyroxine with the same mindset as, say, paracetamol. If a paracetamol tablet were up or down 20% - many of us would not notice any difference. I mean, we tend to take one or two tablets based on "how bad is my head".
The official requirements for paracetamol in the UK and the USA seem to be 90 to 110%.
I was meaning that even if they were way under or over, we as individuals might not notice. A contrast to levothyroxine where a much smaller variations can, and do, get noticed by patients.
I remember Wockhardt oral solution being withdrawn due to higher amounts of liothyronine in it. It is/was my named brand on my prescriptions. I was a bit perplexed to learn that it had liothyronine at all in its ingredients. I was taking 50mcg strength and 68mcg per day. During the recent stock out of liquid in England I was transferred to 125mcg strength and to take 2.5ml a day which I did. I was very surprised after getting my bloods done to see my TSH go suppressed and my T4 and T3 raise so much. I had been suffering since starting 125mcg strength with very stiff and aching muscles everywhere even my stomach muscles. I thought I was maybe under medicated but I was over medicated. Maybe the higher strength has higher concentrations of liothyronine in it??? As soon as I changed back to 50mcg strength I felt much better and remain so.
Recent T3 jump while on higher strength liquid levothyroxine medication.
The liothyronine isn't an intended ingredient - it is an impurity or breakdown product.
We can't know if it was present in the original levothyroxine powder, or formed during manufacture and storage.
The Maillard reactions are what cause browning in most cooking! A reaction between sugar (esp. lactose) and primary amines.
The extract below
BP Update MC2(19)02
MONOGRAPHS
416 Levothyroxine Tablets (revised) MC2(19)03
A market survey had been completed by the BP Laboratory which was undertaken on behalf of the MHRA Licensing division and BP to understand the levels of the Maillard impurity seen in UK products and to support the revision of the Levothyroxine Tablets monograph to include a Related substances test.
Related substances – Maillard impurity (impurity 1) The market survey had shown that the drafted related substances method was suitable for controlling the Maillard impurity and that it was present in all UK marketed products formulated with lactose. The Secretariat reported that the Licensing division were working closely with manufacturers to determine an appropriate limit.
Related substances – other impurities The reports produced by the lab showed the method was suitable for the monograph. A secondary peak limit of 1.0% and a total impurity limit of 5.0%, excluding impurity 1, were proposed which took into account the results of the survey, the Ph Eur drug substance monograph, ICH guidelines and advice from Licensing, which members accepted subject to stakeholder comments.
what do i have to do to my NHS levo tablets to cause a maillard reaction and turn some of it into T3 then .. will putting them in some foil and waving my lighter underneath it while hiding in the bogs work ?........
i reckon i get stiff muscles if overmediated too, Mcpammy ~ including calf, stomach and bladder too. ( not that bladder is a muscle ?is it ... but whatever , it definitely felt 'tense' whan i was overmedicated)
Hi, McPammy. You say that you were told to take 2.5 ml to get your 68mcg usual dose. Unless I've worked it out wrong, and I may have, to get your dose of 68mcg , if you had taken 2.75ml, that would equate to 68.75mcg.
I think , as you can't measure 0.05ml with the syringe, that you should have dosed 2.7ml, which you can do as the syringe is marked out in tenths. 2.7ml would be a weeny ,wee bit out, but as near as dammit. You could still have taken it as a split dose, 1.3ml and 1.4ml.
I worked this out by saying that as 125mcg strength at 5ml is 125mg dose, then it follows that if you half that, a 62.5 mcg dose would be 2.5ml. By taking 2.5ml, I think you took a dose of 62.5mcg, instead of 68mcg. You were under-dosing , rather than over-dosing. It is still a possibility that Zentiva may have been stronger than it should have been. Maybe manufactured at the upper limits , rather than mid or lower limit. I then considered that if you take a tenth of 62.5, which is 0.625, and add it to 62.5, you get 68.75. Therefore, the 2.5ml dose that equates to 62.5 mcg, I added a tenth , 0.25, to. This means 2.5ml plus 0.25ml, equals 2.75ml. See what I mean?
You are absolutely correct. I should have been taking 2.75ml of 125mcg strength to equal 68mcg. Good job I didn’t take any more than 2.5ml though as I went over medicated. I couldn’t believe it really. I knew I was taking slightly less than my usual amount and thought I may have gone under medicated. But my TSH went suppressed and my T4 went higher. Much to my surprise was my increase in T3 level. I’ve read that liquid levo can have an amount of liothyronine in it.
If you knew that you were taking slightly less than your usual amount , why were you taking slightly less? Don't understand that. Did an Endo expect that 2.75ml from a 125mcg bottle would pack a bigger punch in that though it should have equalled 68mcg in theory it would not in practice? Did they know it would overmedicate you to take 2.75ml?
The reason I am asking is because I took 3ml of 125mcg strength to equal 75mcg.
Would an Endo have realised or believed this would result in a dose in excess of 75mcg? I'm confused.
I didn’t see an Endo or GP. I had to find the liquid myself. Hunt it down and get the correct prescription etc. it did take some doing. The pharmacist had no clue what my normal dose was. I just opted to do 2.5ml to see where I ended up to be honest. I’m glad I went slightly lower as I went over medicated quite quickly. All my muscles were so stiff and painful, even stomach muscles. I’m much better now on 50mcg strength and I’m doing my normal 68mcg now split into two doses 34 + 34 daily.
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