This is a question that comes up occasionally from thyroid patients.
If someone is on one type of T3 (or even NDT), and it is being taken in several divided doses per day, but the patient needs to change brands for whatever reason, what is the best way to go about this?
Well, do not wait until one type of medication runs out before ever trying out the new brand. You definitely need to avoid accumulating any of the new brand without testing it to see if it is going to work well. Also, swapping all doses at once is not advisable, as the brands may have different strengths and may even have unwanted side effects.
This advice I always give to thyroid patients is to pick the last dose of the day and swap to the equivalent dose size in the new brand. Try this for a week or two and if all ok then swap your other doses to the new brand and assess them. Assess this over a few weeks. If all ok, and if you have plenty of your original brand left, switching back to the original brand and using the older medication first is sensible (thus keeping the newer medication with the longer expiry dates for later when your original medication runs out).
It is possible however, that the new medication might not work as well as the original same way. So giving it at least a few weeks to assess it, and adjust the new dose strength in tiny amounts in order to make it work in the same way as the previous brand.
At the end of this last-dose-adjustment-process, you will know the equivalent strength of the new brand compared to the old brand. Plus you’ll know if there is some fundamental issue with the new brand (perhaps due to a binder or filler). If you find a problem, then go back to your pharmacist or doctor and tell them quickly so they can give you a different brand. This is why it is essential to begin testing any new brand quickly, even though you may have plenty of the original brand left. Waiting and using up the original whilst accumulating some of the newer brand of medication is not sensible and would likely make your doctor and pharmacist upset if you have to take back a lot of the new brand because you had delayed testing it.
You can now safely adjust one of the other doses and fine-tune if you need to.
Proceed in this way until all the doses have been switched over and thoroughly tested. Once you are confident all is ok then you can go back and use up all of your original brand with the shorter expiry dates before switching to the new brand.
The main thing to do is to start early, well before your old brand has run out.
I hope this helps.
Best wishes,
Paul
