The recent review of treatment for hypothyroidism recommended further research to look at combination therapy. A group in Iran have done the following trial looking at sustained release combination T4/T3. Fascinating…… it suggests that daily sustained release capsules can deliver a stable T3 level over 24 hours without the significant peaks and troughs and looks at different ratios for treatment.
I assume you have a prescription for liothyronine and so were able to get it from Roseway.
This study doesn't look at the pharmacodynamic properties as claimed in its title.
Pharmacokinetics look at 'what the body does to the drug' - how the body absorbs and eliminates a drug.
Pharmacodynamics look at 'what the drug does to the body' - for example how it affects weight or heartbeat. Apart from the effect on TSH the study doesn't look at pharmacokinetics.
I'm being pedantic because all endocrinologists are bogged down in liothyronine pharmacokinetics. They tell you is has a 'very short half-life' because half of it disappears from the blood in a day. Not as short as a glass of water!
What matters is pharmacodynamics, how it affects things like heart rate. My experience from when I was on 80 mcg LT3 was that my overnight pulse was steady, there were no peaks.
We might expect TSH to respond quite quickly to variations in fT3, as quick as most organs. Celi doi.org/10.1210/jc.2011-1329 found that ordinary liothyronine given three times a day produced no variations in TSH. T3 in moderate doses does not cause dangerous peaks in thyroid hormone action, fT3 may peak but its effects do not.
I find this whole subject really interesting. Essentially there is very little good research that gives us definitive answers. My personal experience is that I get some palpitations a couple of hours after taking my T3, especially when I have increased the dose. This is less when I split the dose into 3 or 4 smaller amounts. I also wake almost every night around 3 am when I assume my T3 level is at its lowest.
Tania Sona Smith has said that she thinks that TSH suppression is greater when there are peaks of T3 and spreading the dosage out can help to raise it. ( Something my endocrinologist is keen on!)
I have tried taking 4 doses of 5 mcg a day and found it white inconvenient. I am quite busy looking after toddler grandchildren and often miss it or take it late. I am on Roma capsules, currently 10 and 5 and they are not easy to split. I don’t want the NHS to pay £220 a month for 4 capsules a day so thought I would give the sustained release a go……. It may not work, may not help me sleep and may not increase my TSH but I have to hope! 🤞🤞
I suppose we are all different and know that some people can take very large doses once a day and be totally fine. That’s why I feel so strongly that we should all be able to do what is right for ourselves and why I am so grateful for you fighting the “authorities”
I find it strange that they didn't think to base their ' thinking ' on the original treatment for hypothyroidism which has been used successfully for over 100 years -
Desiccated Thyroid / NDT - where the ratio is stated as 1/4.22 T3/T4 :
Though if the main reason was to keep the TSH in the range - I guess I've answered my own question.
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
Finally, a sustained release T3 going into Phase I trials
Slow release t3 experience 
Slow-release T3 online?
Time released thyroid hormone T4 and T3
