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[Hurdity]

I've been puzzling recently about the general priniciple usually touted in favour of the Mirena, that systemic absorption is minimal. This seemed at odds with the reports that some women (intolerant to synthetic progestogens) react badly to it (while others love it!). How could this be if there is almost no systemic absorption? How could such a device have such a powerful local effect – that it can stop periods way before menopause and yet be barely absorbed into the body? Also because I know from papers that I've read, that more actual progesterone (ie Utrogestan) is absorbed systemically (as shown by higher blood serum levels) when used vaginally than orally at the same dose - I decided to have a look at how much progestogen was actually absorbed from the Mirena.

When looking at the information on the company's website I was reminded that this product was of course developed primarily as a contraceptive and not for HRT initially. Therefore compared for example to the oral combined contraceptive pill – eg Microgynon 30 (150 mcg levonorgestrel) -  absorption (from Mirena) is of course minimal! With the latter (the Pill) the maximum serum concentration is approx 10 times that of Mirena (after 1 year of Mirena – can't find info about max from the start).  The CCP is approx 3-4 times more concentrated (in terms of systemic levels) than the levo mini pill eg Norgeston.

However I was surprised to find – but perhaps not so since I was pondering the above seeming anomaly - that actually compared to Femseven much more is absorbed systemically from the Mirena than the HRT patch. After 4 years the Mirena (on average) is still giving higher levels than Femseven.

There is also a complicated relationship with SHBG (Sex Hormone Binding Globulin) which I don't yet understand sufficiently so have only vaguely got the gist of it - but SHBG is affected by levo and levo binds to it and somehow alters the systemic levels of levo – but it also depends on how much levo is ingested.... aaagh!

However – the major advantage of the Mirena is that it provides contraception as well as endometrial protection, sorts out the heavy bleeding of peri-menopause, and in addition you can add in whatever oestrogen dose you like – so it is very flexible which Femseven sequi is not – it only comes as one 50 mcg dose and those damn Femseven patches don't seem to stick that well for some women as they need to be on for a week (I've never used this type!).

Absorption goes CCP>Mini Pill>Mirena>Femseven sequi/conti. I can upload the actual figures but they're not strictly comparable although when there is an order of magnitude difference it is obvious!

So – compared to the CCP levels of levo (from the Mirena) are much much lower, but if you are post-meno and only want or are happy on a medium dose HRT,  are a bit sensitive to some synthetic progestogens, and have no problems with fibroids then maybe you'd be better off with Femseven..... and of course most women probably are completely unaffected by any of it and oblivious to the detailed scrutiny given to this topic by some of us

I got all the info from  the Mirena website, and the Mirena and Femseven sequi/conti SPCs' ( “Summary of  Product Charatceristics”) – my go to info (section 5.2) for the pharmacokinetics of the hormone ( this being what happens to the hormone over time after it is taken into the body and how long it takes to break down), as well as the SPCs for Microgynon and Norgeston. I am hoping my understanding and interpretation is correct....

By the way this is not meant to put anyone off – but to clarify the whole issue around systemic absorption and not getting it from Mirena!!!

Hurdity x

[dahliagirl]

Hi Hurdity

I seem to have come to the same conclusions as you.

As you say, it is hard to directly compare preparations.  I said I used levenorgestrel on the Mirena thread,  and in hindsight, I also did it for norethisterone, and then cross-compared them.

I was looking to see whether I dared try mirena with my constipation issues and decided not to (hadn't realised how low the progestogen only pill was until I did this!).  I do wish I had written my ramblings and all the sites I visited down.

I have had microgynon/ovranette in the past and not had any issues (except with the constipation but I did not connect it then) with the progestogen - except spots.  This was so much better with the 3rd generation progestogens.  So I am on femoston.  Unfortunately the utrogestan seems beyond the scope of my gp practice but it would be interesting to see how that compares orally, and vaginally in blood levels.

Femseven might be worth a think for the future - if only it would stick

[peri]

Hurdity/dahlia girl this is such a good post and has helped put it all into perspective.  I'm fed up of having periods/withdrawal bleeds but am still anxious about the mirena in case my body reacts badly.  Both microgynon and cerazette left me feeling depressed, conversely I feel good on utrogestan for the first week before it builds in my system and becomes too much.  I think I'm going to risk the mirena and give it a go x

[dahliagirl]

I think it is a 'risk' whatever you do until you have tried it    You seem to have tried 2nd generation, 3rd generation and natural, so it is probably not the 'type' that is your problem.

Some people have trouble with contraceptives with that progestogen in and not Mirena, and vice-versa.

I chickened out.  Sometimes I wish I had gone for it when I had the chance as I still have to take movicol to keep my bowels moving, and the bleeding/dryness/trying to use tampons is annoying.

[Dana]

As much as I can see the attraction of the mirena, I  think I will continue to have a fear of the "unknown" with it. At least with patches and oral/vaginal application you can easily stop if problems arise.

For me, using Provera on a two monthly cycle has proved to be the most attractive. That will obviously become less attractive as time goes on so I think I will probably head towards a continuous method with it. I am aware of the slight concerns of doing that, but nothing in life is ever completely risk free and it's a small risk I'm prepared to take.

I have tried the conti patches in the past and it didn't go well, but I was also taking diazepam at the time, and benzos and progestogens are well known for not working well together. The benzo can magnify the effect of the prog.

Just a side note about the 7 day patches - I have recently tried the estrogen only type (due to a temporary low stock of Estradot) and I found it stuck really well, but the overall dose was definitely lower than Estradot,  and according to my pharmacist that is a common complaint. So might be something to keep in mind.