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TCM herbs (Huang Lian - coptis chinensis...) drug interactions Methimazole

Hello people!

I am very concerned about this. I am currently taking 10mg of Methimazole due to Grave's disease (anti-thyroid drug). I take it at 8AM on empty stomach for about 3 months now. I am also visiting TCM doctor since January, who first prescribed EaseForm Plus (Yia Wei Xiao Jiao Pian) for 14 days and now I am continuting with Huang Lian (the purging herbal mix with Coptis chinensis included). So, I'm eating this 2 pills in the morning (not at 8AM with Methimazole) and 2 in the evening, resulting in about 640mg of Coptis chinensis. I am small and have 45 kilograms.

Now, my thyroid levels have got quite low, am about to fall in hypo state. I was at my endocrinologist this week and told her about the Chinese herbs, but she did not seem to pay attention to them much and said it's fine. She also said that they will put me on Block and release therapy (adding levothyroxine to methimazole, if my thyroid hormones will be too low - and NOT decrease from 10mg to 5mg, she said it's too early, they do this after 6 months MAYBE). I did not get my peace of mind so I started to investigate and found that HUANG LIAN herbal mixture COULD potentially affect drug absorbtion due to inhibiting certain Cytochrome P450 subtypes. There are plenty of researches done, although most are made on rats, with isolated phytochemicals such as berberine (which probably makes no sense to look at for me, because my mix contains whole flowers/roots, not extracts of isolated phytochemicals and therefore the effect might be completely different).

I also noticed that there is grapefruit mentioned in interaction with Methimazole, and it's inhibitor of the same cytochrome HUANG LIAN is supposed to inhibit - should I think from this that my hypo-state is a consenquence of taking HUANG LIAN (because it made methimazole have stronger effect?). Or this is not the case at all? I don't take them at the same time, I wait at least for 2 to 3 hours (or more), before taking HUANG LIAN.

I am just affraid we might be doing something wrong, while nobody knew - nor me, nor he TCM doctor, nor my endocrinologist (she probably does not have a huge knowledge in phytochemicals and pharmaceuticals in general). Concerning my Athyrazol (tiamazole) instructions, only a few drug interactions are mentioned: Wafarin and such (blood thinners), but nothing else, not even grapefruit (I found that information only online, for the American methimazole).

Can someone help me out?!

A.
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649848 tn?1534633700
COMMUNITY LEADER
I can't find anything regarding the coptis chinensis and its effect on thyroid hormones or how it might affect absorption of methimazole.  However, Berberine is a supplement that's used to lower blood glucose levels.  Both being endocrine organs, the thyroid and pancreas must work together to produce adequate hormones.  Berberine is also used as anti-bacterial and for digestive issues.

Grapefruit and grapefruit juice is contra-indicated while taking thyroid medications because it does affect their absorption.  Grapefruit slows the breakdown of methimazole in the body, which may cause overly high levels of the medication in the blood.  It has the opposite effect of replacement thyroid medications (levothyroxine, Synthroid, Levoxyl, etc) by inhibiting uptake transporters and reducing the drug's absorption.  

If you think the supplement is affecting the absorption of your methimazole, stop taking the supplement for a while and see if your thyroid hormone levels change.  Make sure you give plenty of time for the supplement to completely clear your system as it may take a while just as it takes some drugs time to be completely metabolized and out of your system.  I'm not familiar with the half-life of the supplement, but it could take days/weeks for to be completely gone from your blood.

As for the Block and Replace method of controlling your thyroid - that is used, but typically, at this point, the doctor would decrease your Methimazole dose to see if that would help.  Why not control your hyperthyroidism on a lower dose, if possible instead of becoming hypo and having to add another medication to control that?
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