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Author Topic: Build up of Test Cyp from Half Life Process  (Read 21627 times)

Ken

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Build up of Test Cyp from Half Life Process
« on: February 26, 2013, 12:36:23 am »
I'm curious if Peak or someone can accurately explain how T-Cyp does not continuously build up to toxic levels if it has a given half-life (say 5 days for argument purposes) and someone continuously administers a weekly injection of a constant/fixed amount.  For example:

day 1: inject 100mg
day 5: 50mg left
day 7: 40mg (2/5 = 40% of 25 = 10.  50 - 10 = 40)

Now we inject 100mg again.

day 1 100mg + 40mg (leftover from previous shot): 140mg
day 5 : 70mg
day 7 : 56mg (2/5 = 40% of 35 = 14. 70 - 14 = 56)

Now we inject 100mg again.

Day1 100mg + 56mg = 156mg.

And so on ... and so on ....

I realize that a biological half life likely does not behave the same as a radioactive half life and I suspect this is where the confusion is.  But what this difference specifically is remains unclear to me.

So the question is: What keeps the T-Cyp from simply continuously building up while on never-ending HRT?

Thanks in Advance
Age: 52
Wt: 210lb
Ht: 6'1"
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JackAndy

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Re: Build up of Test Cyp from Half Life Process
« Reply #1 on: February 26, 2013, 04:19:52 am »
So the question is: What keeps the T-Cyp from simply continuously building up while on never-ending HRT?

Thanks in Advance

Your body consumes it. Specifically you piss it out because your kidneys filter it from your blood. Eventually an equilibrium is reached.
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Re: Build up of Test Cyp from Half Life Process
« Reply #1 on: February 26, 2013, 04:19:52 am »


PeakT

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Re: Build up of Test Cyp from Half Life Process
« Reply #2 on: February 26, 2013, 04:52:55 am »
http://www.steroidology.com/forum/anabolic-steroid-forum/81826-testosterone-almost-everything-you-could-possibly-want-know.html

"Testosterone is metabolized principally in the liver to various 17-ketosteroids via 2 different pathways. The major active metabolites of testosterone are estradiol and DHT. In many tissues, the activity of testosterone appears to depend on reduction to DHT, which binds to SHBG with greater affinity than does testosterone. Testosterone and its metabolites are excreted in urine and feces. Approximately 90% of an IM dose of testosterone is excreted in urine as glucuronic and sulfuric acid conjugates of the drug and its metabolites; approximately 6% of a dose is excreted in feces, principally as unconjugated drug."
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Ken

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Re: Build up of Test Cyp from Half Life Process
« Reply #3 on: February 26, 2013, 05:03:06 pm »
Thanks Peak,

My "engineer" brain is trying to get a handle on the math involved here.  When I hear "half-life" I think of radioactive isotopes and how they never truly reach zero.  From what I am hearing from you, together with my own looking around on-line, it seems the term half-life when stated with T-Cyp is a bit loosely used. 

It appears what happens is there is a half-life, where concentration levels drop to half of injection dose at 5 or 8 days (depending on your source), and instead of continuing on with the same half-life process, the process changes.  Perhaps there is point at which the active nature of T-Cyp ends, via removal from the body or metabolism as you stated.  So basically you would see an expected half life concentration at the first interval but then it begins to get eliminated from your system at a different non-linear rate reaching zero much quicker than a true half-life process.

Oh well, I was just curious and it appears there is no clear explanation anywhere online as to the exact curve (graph) that a concentration of T-Cyp follows as a function of time.  With such a curve (developed of course with an adequate number of subject data points and subjects) a mathematical model could easily be developed to really understand what concentration an individual has in his system on any given day of his HRT cycle. 

If you know of a curve like the one I just subscribed please refer me.

Thanks Again!
Age: 52
Wt: 210lb
Ht: 6'1"
BF% 12.5

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Re: Build up of Test Cyp from Half Life Process
« Reply #3 on: February 26, 2013, 05:03:06 pm »


JackAndy

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Re: Build up of Test Cyp from Half Life Process
« Reply #4 on: February 26, 2013, 05:46:11 pm »
Well if you ever get tired of buying testosterone, we know where 90% of it is going now. hehehe
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PeakT

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Re: Build up of Test Cyp from Half Life Process
« Reply #5 on: February 26, 2013, 07:17:57 pm »
Thanks Peak,

My "engineer" brain is trying to get a handle on the math involved here.  When I hear "half-life" I think of radioactive isotopes and how they never truly reach zero.  From what I am hearing from you, together with my own looking around on-line, it seems the term half-life when stated with T-Cyp is a bit loosely used. 

It appears what happens is there is a half-life, where concentration levels drop to half of injection dose at 5 or 8 days (depending on your source), and instead of continuing on with the same half-life process, the process changes.  Perhaps there is point at which the active nature of T-Cyp ends, via removal from the body or metabolism as you stated.  So basically you would see an expected half life concentration at the first interval but then it begins to get eliminated from your system at a different non-linear rate reaching zero much quicker than a true half-life process.

Oh well, I was just curious and it appears there is no clear explanation anywhere online as to the exact curve (graph) that a concentration of T-Cyp follows as a function of time.  With such a curve (developed of course with an adequate number of subject data points and subjects) a mathematical model could easily be developed to really understand what concentration an individual has in his system on any given day of his HRT cycle. 

If you know of a curve like the one I just subscribed please refer me.

Thanks Again!

Well, you ask the same question with Cialis.  It has a half life of 36 hours I believe and many men are taking it daily or every other day.

I have not seen a graph either.  Again, I can tell with reasonable certainly that most men peak on about day 4 and you're pretty much down to zero at about day 10. 

But the "devils always in the details", eh?  The one thing that I know is true is that men reach a steady state condition and it holds there.  Furthermore, they reach this rather quickly.  This can modify slightly with factors like muscle gain, weight loss, HPA feedback, enzyme/receptor sensitivity modification, etc.  It's all quite complicated and I don't think anyone has ever studied in detail the tweaks that occur at day one, week one, month one, year one, etc.

But let me try to find out the standard thinking out there for you:  I've got a few pointy-headed people I can ask...
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If you are on medications or have a medical condition, always check with your doctor first before making any lifestyle changes or taking new supplements.  And low testosterone is a medical condition.

Quincy

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Re: Build up of Test Cyp from Half Life Process
« Reply #6 on: April 11, 2013, 10:15:52 pm »
Thanks Peak,

My "engineer" brain is trying to get a handle on the math involved here.  When I hear "half-life" I think of radioactive isotopes and how they never truly reach zero.  From what I am hearing from you, together with my own looking around on-line, it seems the term half-life when stated with T-Cyp is a bit loosely used. 

It appears what happens is there is a half-life, where concentration levels drop to half of injection dose at 5 or 8 days (depending on your source), and instead of continuing on with the same half-life process, the process changes.  Perhaps there is point at which the active nature of T-Cyp ends, via removal from the body or metabolism as you stated.  So basically you would see an expected half life concentration at the first interval but then it begins to get eliminated from your system at a different non-linear rate reaching zero much quicker than a true half-life process.

Oh well, I was just curious and it appears there is no clear explanation anywhere online as to the exact curve (graph) that a concentration of T-Cyp follows as a function of time.  With such a curve (developed of course with an adequate number of subject data points and subjects) a mathematical model could easily be developed to really understand what concentration an individual has in his system on any given day of his HRT cycle. 

If you know of a curve like the one I just subscribed please refer me.

Thanks Again!

Ken, the way I understand how the half life works is it continually breaks down in half cycle after cycle. So for example if the cypionate half life is 7 days and you inject 100mg every 7 days, you will ramp up with additional T (100mg weekly) while previous T will continue to half every 7 days. After a few months you will reach equilibrium with a high level of 200mg of T in the muscle tissue and by the end of the 7th day it will cycle down to 100mg in the muscle tissue. At that point it is just a weekly wave back and forth between 200mg and 100mg with your blood absorbing 100mg/weekly.

Check this spreadsheet out for the actual math behind it. You can download this SS and change the figures in it as they are my actual dosages since starting TRT.

https://www.box.com/s/4d8nmf7pc91d3kyx8qgv
56yo, Pre  T level 239
Previous dosage 180mg T.cypionate weekly BW @ 1056 on 7th day of cycle
Previous dosage 100mg T.cypionate weekly BW @   414 on 7th day of cycle

Current dosage  140mg T.cypionate weekly

Ken

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Re: Build up of Test Cyp from Half Life Process
« Reply #7 on: April 11, 2013, 11:12:02 pm »
Thanks Quincy,

I only had a chance to briefly look at the spreadsheet.  I will look closer at it tomorrow.  I see the standard equation for half life but I also see some numbers in the column for "amount per day" that appear to be calculated linearly versus the natural log that the equation implies.  Anyway, I only looked at quickly and I will try to look closer tomorrow.  Busy at work at the moment.
Age: 52
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PeakT

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Re: Build up of Test Cyp from Half Life Process
« Reply #8 on: April 12, 2013, 03:38:28 am »
Quincy,

You are exactly right!  I proved that with my own spreadsheet, although I did not use a true half life equation.  But, yes, of course it peaks after a few cycles and then stays constant!  Makes a lot of sense and I'll bet you this is the primary explanation.  I know that this will definitely cap the amount in your system.

There may be other physiological reasons of course such as JackAndy brought up, but at least this shows that you will not get a runaway effect.
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davie12

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Re: Build up of Test Cyp from Half Life Process
« Reply #9 on: April 12, 2013, 09:14:43 pm »
If you were combining HCG EOD, would one try to estimate the expected natural T production from the dose taken on those days and incorporate that into the spreadsheet? (I suppose that may not work, as the spreadsheet is in mg of test while HCG is a different unit of measure. I suppose the only way to do it would be to estimate what mg level corresponds to what total T level in another column.)
« Last Edit: April 12, 2013, 09:28:28 pm by davie12 »
Recovering from adrenal fatigue through Paleo diet+exercise+vitamins/supplements; formerly used HCG & Clomid at various dosages

Quincy

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Re: Build up of Test Cyp from Half Life Process
« Reply #10 on: April 13, 2013, 01:38:01 pm »
One thing that is a little confusing about the T levels in the spreadsheet is it is measuring the amount of exogenous T that is deposited into your muscle tissue... not your actual serum T level. I would love to know what that is but you would need a lot of data points of actually serum readings to correlate it with the T in your muscle tissue. And evidently that varies quite a bit between individuals.

As I continue to get BW done in the future, I will plug that info into the SS. Hopefully someday I will be able to create a reliable model of how it effects me.
56yo, Pre  T level 239
Previous dosage 180mg T.cypionate weekly BW @ 1056 on 7th day of cycle
Previous dosage 100mg T.cypionate weekly BW @   414 on 7th day of cycle

Current dosage  140mg T.cypionate weekly

Ken

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Re: Build up of Test Cyp from Half Life Process
« Reply #11 on: April 17, 2013, 10:23:28 pm »
Quincy,

I finally got a chance to look at this process properly and look at your spreadsheet.  The equation you are using is a bit different than the half-life equation I'm used to seeing for radioactive isotopes.  However, even if I substitute my equation for yours it still demonstrates that saturation is reached fairly quickly in somewhat of an asymptotic manner. The numbers become a bit lower with my equation but still follow the same curve shape as yours.  I think my brain was cramping when I started this thread.  After thinking back to college freshmen physics I remembered that this should indeed occur.  Now with all of that said:

I tried out of curiosity to alter the half-life values to see what results.  Perhaps you tried this as well.  It demonstrates nicely what the effect of half-life has in the buildup process.  For example, if I use my numbers of 150mg/week with a half-life of 7 days, I saturate at 300mg in about 4 to 5 weeks of injections.  However, if hypothetically you get get T in an ester that has a 21 day half-life, at my same dosage of 150mg I would saturate at 726 but it would take me about 25 weeks to get there.  Of course this is an extreme example just to demonstrate how longer half-life delivery has it's advantages.  The only disadvantage would be a longer time required to build up to saturation.

There continues to be some debate on exactly what the correct half-life is for T-cyp and T-enen.  It is suggested that T-cyp has about a 1 day longer half-life as a result of an extra carbon atom (or something like that).  You can read half-lifes for both of these anywhere between 5 and 12 days depending on your source.  7 days seems like a rational guestimate.  And of course the half-life for the same compound in one guy might be different than it is in the next guy due to different body chemistry's and how quickly they break the T from its ester.

Anyway, after all of this I am a fan of longer half-life now.

And thanks a lot for the replies and your spreadsheet.

Cheers

Age: 52
Wt: 210lb
Ht: 6'1"
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PeakT

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Re: Build up of Test Cyp from Half Life Process
« Reply #12 on: April 18, 2013, 12:41:24 am »
For example, if I use my numbers of 150mg/week with a half-life of 7 days, I saturate at 300mg in about 4 to 5 weeks of injections. 

Interestng post.

The half life from pretty reliable sources is 5-8 days for cypionate.  So there's likely a little variability with individuals obviously which might be why you read differeing values.

The half-life of cypionate when injected intramuscularly is 8 days straight from Pfizer itself.  (See below.) You will see out on the web 5-8 days quoted and 12 days as well for testosterone cypionate's half-life.

http://www.pfizer.com/files/products/uspi_depo_testosterone.pdf
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If you are on medications or have a medical condition, always check with your doctor first before making any lifestyle changes or taking new supplements.  And low testosterone is a medical condition.

Sam

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Re: Build up of Test Cyp from Half Life Process
« Reply #13 on: April 18, 2013, 01:37:21 am »
Sounds to me like half-life for the metabolism of a drug is a broad estimate.  It cannot be predicted as accurately as radioactive decay because radioactive decay is a physics issue.  Half-life is a biological system is an estimate based on the expected metabolism and natural excretion process.  Important to note that the human liver has a total amount of cytochrome p450 enzymes and some people have more of one than another.  For instance an alcoholic will have a higher amount of cytochrome p450j.  That's how you build up alcohol tolerance, you condition your body to get rid of it faster but can also cause your liver to not do other things as well.

http://en.wikipedia.org/wiki/Cytochrome_P450

It's also a major reason for bad drug interactions where one drug can inhibit the metabolism of another drug causing it to build up to dangerous levels.

Paracelsus, sometimes called the father of toxicology, wrote:
"All things are poison, and nothing is without poison; only the dose permits something not to be poisonous." - The does makes the poison

In other words what you are talking about is highly variable by person and really just a rough idea and the reason why a pharmaceutical dose is typically way below a toxic dose and drug companies have to do lots of research to figure all of this out for a broad population to ensure they are not killing people.

It's also why the field of companion diagnostics is growing so quickly so that doctors can know exactly how to treat a patient based on their particular make up.  Aka personalized medicine.   For those on TRT personalized medicine means continuously monitoring and adjusting based on an individuals symptoms and blood levels.   It's also important to note that other aspects of your lifestyle can impact how you respond or don't respond to t therapy.

I think this is right....
« Last Edit: April 18, 2013, 02:24:46 am by Samson1971 »

PeakT

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Re: Build up of Test Cyp from Half Life Process
« Reply #14 on: April 18, 2013, 03:15:00 am »
Yes, although there are other things that would slow down an intramuscular injection. 

Also, some docs are doing subQ now:

https://www.peaktestosterone.com/forum/index.php?topic=841.0
THE MOST COMPREHENSIVE BOOK ON TRT/TESTOSTERONE:
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And check out my New Peak Testosterone Program: http://www.peaktestosterone.com/peak_testosterone_program
If you are on medications or have a medical condition, always check with your doctor first before making any lifestyle changes or taking new supplements.  And low testosterone is a medical condition.

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Re: Build up of Test Cyp from Half Life Process
« Reply #14 on: April 18, 2013, 03:15:00 am »