Some results from my Depo-T Absorption Calculator

[ASaxon]

Determined to understand the dosing of Depo-T I created a absorption calculator in Excel that calculates the absorption levels of Depo-T over time and graphs the daily concentrations of Active T in the blood. I did this so I could see the difference between the various dosing possibilities. Id post the graphs but I dont have a location to host the charts so Im just including the summary numbers. It's interesting to see how doubling the first dose helps stablize T-levels very quickly as opposed to just starting the regular dose.

Note: These values are only after treatment on a dose for at least 45 days so that ramp up values are not evaluated. These calculations assume a Depo-T half-life of 8 days as published.

On 100mg every 7 days we have:
18.251 - Maximum Daily Concentration (mg)
14.244 - Average Daily Active Concentration (mg)
9.951 - Minimum Daily Concentration (mg)
8.300 - Change in Concentrations During Cycle (mg)

On 200mg every 14 days we have:
23.622 - Maximum Daily Concentration (mg)
14.257 - Average Daily Active Concentration (mg)
7.599 - Minimum Daily Concentration (mg)
16.023 - Change in Concentrations During Cycle (mg)

On 150mg every 7 days we have:
27.377 - Maximum Daily Concentration (mg)
21.366 - Average Daily Active Concentration (mg)
14.927 - Minimum Daily Concentration (mg)
12.449 - Change in Concentrations During Cycle (mg)

On 300mg every 14 days we have:
35.433 - Maximum Daily Concentration (mg)
21.385 - Average Daily Active Concentration (mg)
11.398 - Minimum Daily Concentration (mg)
24.035 - Change in Concentrations During Cycle (mg)

On 200mg every 7 days we have:
36.502 - Maximum Daily Concentration (mg)
28.488 - Average Daily Active Concentration (mg)
19.903 - Minimum Daily Concentration (mg)
16.599 - Change in Concentrations During Cycle (mg)

On 400mg every 14 days we have:
47.244 - Maximum Daily Concentration (mg)
28.514 - Average Daily Active Concentration (mg)
15.197 - Minimum Daily Concentration (mg)
32.047 - Change in Concentrations During Cycle (mg)

Just thought Id post this. Im still analyzing various dosing amounts and schedules but its interesting that my current dose of 400mg every 14 days has a swing in concentrations twice as much as 200mg every 7 days, which makes sense.

Scott

 

[ASaxon]

Oh and heres the dosing for a steroid user.

A dose of 1000mg every 7 days.
182.511 - Maximum Daily Concentration (mg)
142.440 - Average Daily Active Concentration (mg)
99.515 - Minimum Daily Concentration (mg)
82.996 - Change in Concentrations During Cycle (mg)

Interesting!

Scott

 

[wildfox]

Interesting. How about for smaller amounts more frequently?

WF

 

[ASaxon]

I posted some more frequent doses but something's screwy with the calculator when using less than a 7 day cycle. I'll figure it out and post the results.

UPDATE:

Figured it out.

I can only do whole day cycles so putting in a cycle of 3.5 days gives a 7 day cycle so I had to do a 3 day cycle and a 4 day cycle then average the results. Here’s what I got.

On 75mg every 3 days:
27.044 - Maximum Daily Concentration (mg)
24.605 - Average Daily Active Concentration (mg)
22.404 - Minimum Daily Concentration (mg)
4.640 - Change in Concentrations During Cycle (mg)

On 75mg every 4 days:
21.135 - Maximum Daily Concentration (mg)
18.562 - Average Daily Active Concentration (mg)
16.132 - Minimum Daily Concentration (mg)
5.003 - Change in Concentrations During Cycle (mg)

Averaging we get (for 75mg every 3.5 days):
24.090 - Maximum Daily Concentration (mg)
21.584 - Average Daily Active Concentration (mg)
19.268 - Minimum Daily Concentration (mg)
4.822 - Change in Concentrations During Cycle (mg)

Likewise, averaging 50mg every 3.5 days we get:
16.060 - Maximum Daily Concentration (mg)
14.389 - Average Daily Active Concentration (mg)
12.845 - Minimum Daily Concentration (mg)
3.214 - Change in Concentrations During Cycle (mg)

That you go.

I’m pretty sure these are correct but if you notice anything strange let me know.

Scott

 

[pmgamer18]

I am not sure what your doing but it looks like every 3 or 4 days is better not so high so less E2 problems. If I am wrong tell me.

 

[Ruper]

I'd really like to know the time to the peak (I assume an exponential decay after the peak).

I guess I could just calculate it from your numbers, but it would be easier to ask. (EDIT - I'm guessing the peak is ~24 hours after injection?)

Also do you ramp linearly to the peak, or use some other function?

Any idea (anyone) on the range of extra T 250IU of hCG will give for someone who is secondary - or is that just a huge variation.

 

[Ruper]

Just thought I’d post this. I’m still analyzing various dosing amounts and schedules but it’s interesting that my current dose of 400mg every 14 days has a swing in concentrations twice as much as 200mg every 7 days, which makes sense.

Scott

Yes, it's easy to come to the conclusion that if you have to exceed 100mg every week by much, then you might be better off doing less every 3-4 days instead.

 

[chap]

How about the concept that the published 8 day half life is completely wrong.
Also the concept that the absorption of a steroid ester is not linear.

Interesting exercise in spreadsheet skills, but I think the real life application of the data is not useful.

 

[ASaxon]

I'd really like to know the time to the peak (I assume an exponential decay after the peak).

I guess I could just calculate it from your numbers, but it would be easier to ask. (EDIT - I'm guessing the peak is ~24 hours after injection?)

Also do you ramp linearly to the peak, or use some other function?

Any idea (anyone) on the range of extra T 250IU of hCG will give for someone who is secondary - or is that just a huge variation.

My calcs are based on how much Depo-T is absorbed into the body. The formula to calculate how much Depo-T remains in the body from a single injection is:

y=(original dose) * 1 / 2 ^ ((Day number after inject)/(half life in days))

Note: the ^ symbol means raised to the power of.

I see no point in putting in 24 or 48 hour ramp up curve at the beginning of this as after you reach peak you will just decay as if the peak was immediate. There would be a small difference as the amount of Depo-T present at a peak 48-hours after injection would be slightly less than the injected amount but I don’t think by that much. Plus, I just want to get a accurate estimate not an actual 100% accurate model.

So if you wanted to find out how much Depo-T (with a half life of 8 days) was left form a 100mg injection after 5 days you’d calculate it as:

y = 100 * 1 / 2 ^ ( 5 / 8 )

y = 100 * 0.6484

y = 64.84 mg

So after 5 days a 100mg injection roughly has 64.84mg of Depo-T that has not been activated via enzyme activity. This also means that 35.16 mg has been activated over that 5 day period.

You also have to remember that if someone was to inject another 100mg at 5 days the total Depo-T in their system would then be 100 + 64.84 = 164.84 mg just waiting to be cleaved by enzyme action into active T. As we all know this means that injections overlap in their absorption into the body so figuring out the actual absorption of all Depo-T in the body form all active injections is the process by which we can determine how much actual Depo-T we absorb and activate on any one day.

The calculator I created looks at the overlapped dosing to get the total absorbed from day to day.

Scott

 

[ASaxon]

How about the concept that the published 8 day half life is completely wrong.
Also the concept that the absorption of a steroid ester is not linear.

Interesting exercise in spreadsheet skills, but I think the real life application of the data is not useful.

Pfizer states in there Depo-T patient information sheet that:

The half-life of testosterone cypionate when injected intramuscularly is approximately eight days. (source: http://www.pfizer.com/pfizer/download/uspi_depo_testosterone.pdf)

And the decay I use is not linearsorry!!!

 

[1cc]

www.roidcalc.com

 

[chap]

I know that the pfizer data sheet states that, but it is commonly accepted amongst many experts that that data is wrong, and the formula you are using assumes a rigid half life decay as if you were talking about radioactive isotopes, whereas the biochemical pharmacokinetics are not even close to a true "half life" decay pattern that that describes.

The data makes a good conversation piece, but I believe in real life that it does not even come close to a true description of blood levels of hormone on a day to day basis.

 

[ASaxon]

Well I don't know what to say about that...making claims with no evidence or references is hard to argue against, or argue for, for that matter. I don't give much weight to opinions over that of scientific studies so I really can't see your point. But to each their own...I think it's a useful tool if only to approximate the physiological response to Depo-T injections. And anyhow, if I learned of a more reliable piece of data with a different half life Id just plug it into the calculator and it will adjust the calculations accordingly. Of course if you dont think any calculators are useful then you can always just ignore them.

 

[chap]

I'm going to have to search for some references, but from relatively current theories I've heard the first 'half-life' for cypionate approximates 4 or 5 days, and the succeeding ones are not linear in that the levels 'decay' to zero much more rapidly than a 1/2 by 1/2 by 1/2 by 1/2 .... kind of model, which makes a calculator difficult to adapt to the way a biological metabolism works.

I'll do some searching around to get some references.

 

[chap]

just quickly I found a more current product sheet on enanthate that claims a half life of 4.5 days for enanthate:

http://www.medsafe.govt.nz/profs/Datasheet/p/Primotestondepotinj.htm

I have seen other more specific on this subject, I'll keep on searching.

 

[chap]

here is a post I found on another board that is very learned, not exactly a reference but food for thought on the subject:

post by 'Body By Balco':

The problem with checking other boards for this type of information is that is the same misguided BS over there as well. A better rule of thumb is 0.7 X the number of carbons in the ester to apporximate the half life. On top of that the user needs to bear in mind that esters decay in a non linear manner. That is to say more ester is released form the depot (or fatty tissue in which it is dissolved) on injection day +1 then is released on injection day +2. Picture a sharply downward sloping curve on a graph, with release amont on the vertical axis and time on the horizontal axis, not a gentle curve.

Even with a long ester things are quite different on injection day +4 than on injection day +1. Massive amounts (in relation to the total amount injected) have already been released on injections days +1,+2 and +3. That 1.5 X the number of carbons in the ester half live approximation simply do not add up. No one has shown proof for ther validity of those estimates. I have shown my evidence for my 0.7 rule several times.

 

[ASaxon]

The eight day half-life I am referring to is for Depo-T testosterone cypionate not Primoteston Depot testosterone enanthate. Testosterone enanthate might very well have a 4.5 day half life.

<<Modified Post>>
I was thinking about this, I think I misunderstood what he was saying. He's looking at it from more of a chemical basis the physiological one.

<<Deleted Text>>

On top of that the user needs to bear in mind that esters decay in a non linear manner. That is to say more ester is released form the depot (or fatty tissue in which it is dissolved) on injection day +1 then is released on injection day +2.

This is true in standard half-life decay calculations as well just due to the larger concentration of what is being decayed or absorbed on day 1 than on day 4 or 10. I’d have to see the context of this post because it looks to me like this guy was arguing against the idea that linear decay means that the decay amount is the same every day. I’m not sure what point he’s contradicting here but I don’t think it was a standard half-life calculation. Half-life calculations do not decay the concentration linearly so I’m not sure what he’s referring to here..

 

[chap]

so you believe that cypionate has almost twice the "half life" of enanthate?

here is a reference to a study that shows that with testosterone cypionate or testosterone enanthate, the blood levels go from 0 (basal) back to 0 (basal) in 10 days! So that is not a half life of 10 days, that is the total 'life cycle' of the drug in the body.

attached is an important graph of the pharmacokinetics, and the reference to the study:

Schulte-Beerbuhl M et al., Comparison of testosterone, dihydrotestosterone, luteinizing hormone, and follicle-stimulating hormone in serum after injection of testosterone enanthate or testosterone cypionate. Fertility and Sterility (1980) 33.2 : 201-203.

 

[ASaxon]

Yes, I believe that different esters have different absorption qualities. I think it’s incorrect to say that all esters have the same absorption properties. I’m just amazed that you’d be so quick to grab a graph from a post on a message board and use it as a reference over that of Pfizer who actually produce and test the product under FDA regulation.

I don’t get your rationale here.

 

[chap]

the graph is not from a message board, that is the reference to the peer reviewed study that produced that graph

My rationale comes from decades of my own use and also from coaching dozens of elite athletes and witnessing first hand the results of different dosing strategies. If the "half-life" of cypionate was indeed 8 days then what I have seen in the real world would not make sense, and obviously vice versa.