There is a degree of variability in absorption - in fact according to the paper I read the variation was as much as 10 fold - that is - in the eventual total blood levels of estradiol achieved. I don't know how that translates into how much is absorbed over the 3.5 day interval - but yes patches are designed to deliver the dose consistently and this declines gradually over 7 days. I don't think the patch does not actually run out of oestrogen as such because it contains way more than is actually absorbed. If you google SPC (Summary of Product Characteristics) then you can see the amount for each patch. eg Evorel 50 mcg contains 3.2 mg estradiol. Some of the differences will be due to how well they stick to each woman and skin types and coming a bit unstuck too - I notice my estradot patch is not so well stuck when I come to change it (approx 3.5 days). If it "feels" as though it's running out before the allotted time, then a higher dose is probably needed - but if you are peri-menopausal then you can't definitively say the patch is the reason as your own hormones will be fluctuating. Some women change their patches every 3 days but changing too often is also counterproductive as it takes about 12 hours to build up to steady state after applying it.
Hurdity x
