T Nation

Arimidex Timing Question

First post here but I have been reading for months and have to thank KSMan and all the other helpful people who share here. Canadian guy living in Korea who started TRT in April.
I just read a recent KSman reply to a post about taking AI timed with T injection. What I would like to know is why we don’t try to do it EOD? My reasoning being that arimidex had close to a 48 hour half life and by taking it every 2 days we should reach a steady state after a short time with consistent levels of AI in the system, no? Same goes with the T with 7-8 day half life where after 40 days I believe, we reach a steady state.

Are we saying that the T is not in fact released somewhat evenly over its half life and we have to attack it with the AI right away? Please help me understand.

Personally, my doc had no idea about using an AI for TRT. I started in April and just tested E2 for the first time at my request 2 weeks ago. Came in at 65 (way out of the ranges which I can post later). Anyhow, convinced her to prescribe me Arimidex at 1mg/week as per recommended in stickies. However, I cut it up into 4 and take EOD with the idea of getting into some consistent level based on half life.

Any feedback on how and why to time AI differently would be greatly appreciated. Thanks again for sharing your time and knowledge here.

Serum anastrozole needs to roughly match serum bio-available T levels, after all, it is a competitive drug.

For those injecting T twice a week, AI twice a week will have T and anastrozole levels roughly rising and falling together. T subq will be steadier than T IM.

Some do T, AI and hCG EOD with hCG driving EOD.
T twice a week is more convenient for some and seems to work well.

You can dissolve anastrozole in vodka or similar and dispense by the drop or volume.

Thanks KSMan. That is helpful. I had no problem cutting 1mg into 4 pieces so based on your answer,should be no harm in taking EOD even though T injection is twice a week.

As for blood test, I would really like to know if I am on the correct dose. How soon after starting AI can I test again to see if my 65 is approaching that ideal 22 level? I would think almost right away.

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Anastrozole is absorbed well and quickly. T–>E2 is reduced very soon. However, because of half-life effects, it takes a few days to establish steady state serum levels of anastrozole then blood levels of E2 take a few days to find a balance between reduced production and metabolization. You can expect to feel definite changes in 7-10 days. Some brain patterns will evolve over time depending on what changes were made by high E2 levels. In some cases, guys feel re-born.


Excellent. It has been two weeks for me. Some slight improvement but mood and wood were already pretty good. My main concern was despite intense exercise and good nutrition, I experienced basically no physical changes in musculature or body composition since starting. Some gains in strength. Anyhow, hoping E2 control will help with this as well.