I collected all of the available data on the number of estrogen patches that the studies have used, and plotted the measured serum estradiol level versus total milligrams of estrogen used every week.
I was pleasantly surprised when all five of the data points fell almost perfectly on a straight line! That rarely happens in prostate cancer research.
It makes sense, though, that the concentration of serum estradiol should increase proportionately as the dose of estrogen increases...you're feeding the body with estrogen. There is no sign of leveling off or non-linear behavior.
This plot will help doctors and clinicians pick the right estrogen dose ( # of patches) for their patients. I hope to be able to generate a similar plot for men who use estrogen gel, although that is less standardized. Some men may need to titrate (adjust) the number of patches in order to reach a desired amount of castration (for example, T < 10 ng/dL)
Low-dose estrogen (2 patches per week) can help manage hot flashes in men on ADT, while high-dose estrogen (4 patches, changed twice a week) can be used to chemically castrate men without having the bad side effects of Lupron ADT.
In this latter case, men should be able to simply replace Lupron ADT with high-dose transdermal estrogen (patches, gels, or IM shots).
Or, they can combine Lupron ADT + transdermal estrogen (either low-dose or high-dose). There would likely be a synergistic effect of combining the two, although this remains to be studied in the high-dose setting.
The ultimate goal for castrate-sensitive men is to get their testosterone down to < 10 ng/dL, and preferably less than 5 ng/dL. Some men on estrogen have gotten their T down to 3 ng/dL, which is a fantastic number!
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janebob99
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I use three .1 mg patches changed weekly . Is there a difference in absorption or efficacy between changing once weekly and twice weekly? I change once weekly for convenience and my T is <.3 and psa is <.1. If I reduced the number of patches say to two weekly do you think it would matter?
I'm not currently taking estrogen. I plan on doing it in 3-4 months, though, when I start my treatment plan.
My DHT is currently 166 pg/mL after 3 month on Dutasteride. It's bout a factor of 10X higher than I'd like it to be. I'd like to get down to about 10-20 pg/mL. It does take months for the DHT to respond to Dutasteride, so I expect it will continue to drop over the next 1-3 months. If it doesn't, then I will increase the Dutasteride dose to 2.5 mg/day (I'm currently taking 0.5 mg/day).
My PSA dropped from 10.0 down to 3.3 after taking Dutasteride for 3 months. (a 70% drop). I expect PSA to continue dropping to about 1-2 over the next 1-3 months, as the prostate and (hopefully the tumor) continue to shrink.
Here is plot of Estradiol concentration vs time for changing 2 patches twice each week (total = 4 patches per week).
[For reference, the PATCH study used four (100 microgram) patches, changed twice weekly (total of 8 patches per week, for a total weekly dose of 800 micrograms (0.8 mg).]
To answer your question, applying, for example, 4 patches once per week or 2 patches twice per week will give the same total weekly E2 dose, and the long-term, average serum estradiol concentration will be roughly the same either way (after a startup period of 4-6 weeks has been completed).
The PATCH study changed patches twice every week. You may want to do the same.
I've attached a graph showing a schematic example of twice-weekly dosing (2 patches every 3.5 days) for a 100 microgram/day E2 dose for a single patch. This is taken from Langley (2008). You can see that the time to reach the peak concentration is about 20 hours, and that the half-life is also about 20 hours. It should the take about 1-2 months of multiple 3.5 day cycles to reach pseudo, steady-state, equilibrium concentrations (so, the first month's measurement may be artificially low because equilibrium hasn't yet been achieved).
Blood lab measurements should be taken at the exact same time in the weekly dosing cycle, preferably at the trough, in the afternoon, just before applying a new patch the next morning.
Note that the half-life varies considerably between different manufacturers. Some can be as long as 100 hours. Having a longer half-life will affect the steady-state serum estradiol levels. so, it may be necessary to titrate the number and frequency of patches until the desired level of serum estradiol, and testosterone nadir level, is reached. A desirable goal for T nadir is a sub-castrate level (< 10 ng/dL, and preferably 1-3 ng/dL), which is achievable with high-dose transdermal estrogen (TDE).
To convert 1 pg/mol to pg/mL multiply 1 pg/mol by 0.29 to get pg/mL. So, 800 pmol/L would equate to 232 pg/mL (the peak of the second cycle in this plot).
For reference, the high end of the normal range of estradiol for a pre-menopausal woman is about 400 pg/mL. To achieve effective chemical castration with high-dose transdermal estrogen (patch or gel), the steady-state (equilibrium) Estradiol concentration should be in the range of 250 - 400 pg/mL (equivalent to a pre-menopausal woman). The normal range of estradiol for men is 10-40 pg/mL, for reference.
I Have found it best to be consistent use the same brand as different absorption rates may occur depending on multiple factors for instance Manufacturers proprietary ingredients and the individuals physical reaction to them. Also consistancy of application (same time of day same day of the week)
I get mine at Krogers Pharmacy. Was getting them from CVS prior. My urologist game me 36 renewals! But I get one months worth at a time or 12 patches, four to a box. I had been getting a thin translucent patch from CVS but pain to scrape off the adhesive. The ones from Kroger are thicker and easier to put on and remove.
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Gynecomastia from ADT - how much?
Estrogen & PC 
