I've just has a look at the product details for Utrogestan - because I was wondering why it is not completely continuous ie 100 mg for 25 days out of 28 days cycle, and this is what it says:
"Alternatively 100 mg can be given at bedtime from day 1 to day 25 of each therapeutic cycle, withdrawal bleeding being less with this treatment schedule."
So it is not quite a conti - in that there might be a small bleed, and presumably also there may be some symptoms on withdrawal - for those who are negatively affected. Maybe as the dose is low this might not be as severe as with 200 mg?
The other interesting point was that studies showed quite large individual variations in plasma progesterone levels after taking it orally - but that the individual responses stayed the same over several months, "indicating predictable responses to the drug". ie if you absorb a lot of it and reach a high concentration then you will most likely continue to do so each month. Presumably that is one of the reasons why some women find it works for them and others have bad side effects - maybe levels are too high. Again a reason for being able to prescribe the right amount for each individual!!
http://www.medicines.org.uk/emc/medicine/19895/SPC/Utrogestan%20100mg%20CapsulesIt also means that for those who still have heavy bleeds on sequi HRT this might be a good compromise - because the more or less continuous prog prevents the womb lining building up so much - but what does build up is still shed.
Hope that makes sense? I am thinking aloud with all this and still trying to work it out.... and as you say jaycee I wouldn't have even thought about it had it not been for Candy's earlier posts.
Hurdity x