Anti thyroid medicine 3 times or all at once?

[MAB5]

Tapazole, 3 tabs by mouth daily. My question all 3 at once or 1 tablet 3 times a day? Finally seen a specialist, medicine changed, blood work results soon, another blood test in 6 weeks. Graves disease, she thinks.

[helvella Administrator Thyroid UK]

MAB5,

In the UK we usually see Carbimazole (rather than Tapazole - which is Methimazole). I think the biochemistry is pretty much the same as Carbimazole is converted into Methimazole.

Carbimazole has a short half-life. If you only take it once a day, the levels can drop far enough to allow your thyroid to produce thyroid hormone again. Therefore, the advice is very often to take it twice a day. If, however, you take it three times a day, I don't think that would matter in the least.

When people have their dose reduced to a low, long-term maintenance dose, it is often acceptable to take that once a day. But consistency is important.

Your profile doesn't say which country you are in!

[MAB5 in reply to helvella]

Thank you, Helvella, I am in US. I am to take 3 tablets and I assumed 1 tablet 3 times a day but the bottle just says take 3 tablets daily. I was unsure, my meds were changed and the other was 2 x daily. I was feeling rather bad around mid to late afternoon. I was taking all 3 at 7pm.

[Valarian in reply to MAB5]

Usual advice with Carbimazole seems to be to split the dose at first, then take the whole lot at once as thyroid levels improve and the dose is reduced. I was on 40 mg/day to start with, which came in 2x 20 mg tablets, so I took one dose in the morning, and one in the evening. I think methimazole has a similar half-life, so the the approach is likely to be similar. My endo was more concerned that I got the full dose than whether I split it or not, so if you struggle to remember the second tablet , maybe take it all at once. Best plan would be to check with your endo or pharmacist . Note that I’m only taking anti-thyroids - I’m not sure what is advised if you are taking thyroid replacement at the same time (ie 'block and replace').

You say your meds were changed, was this from something other than methimazole, or from one brand to another ? In the UK, we can only get carbimazole in 20mg or 5mg tablets, and this tends to govern how we take them throughout the day.

[MAB5 in reply to Valarian]

Thank you, Valarian, for your response. I was given at first Propyl-Thyracil or PTU, ( bad for liver ) then switched to 30mg a day of methimazole, and I take a beta blocker twice a day. I think I need to take it every 8 hours because I just felt bad after lunch to mid afternoon. I think that my dr was not concerned as well or she would have stressed when to take it. After taking the 3 pills all at once I had nausea and stomach cramps, so I will switch to 3 doses.

[Valarian in reply to MAB5]

MAB5 - splitting the dose over a day shouldn’t make things any worse, and as you suggest may help with nausea. I never suffered from that, I had hives instead, but they cleared up after a month or so, and could be managed with antihistamine.

Interesting that you were prescribed PTU initially - carbi is generally first choice here (except, I think, in cases of pregnancy).