kenny345king
New member
PCT - Half lifes
hi everyone
im sure you all know roughy what the half life is of your favorite testosterone esters, and when to start post cycle therapy (pct) after your last jab.
Seen some important infomation about post cycle therapy (pct) start times, and I would like to know what you guys think whats your opinions on this?
Half-lives, AIs and post cycle therapy (pct)
--------------------------------------------------------------------------------
There has been recent discussion on this topic, and I thought more might be beneficial. The biological half-life or elimination half life of a substance is the time it takes for a substance (for example a metabolite, drug, signalling molecule, radioactive nuclide, or other substance) to lose half of its pharmacologic, physiologic, or radiologic activity, as per the MeSH definition. In a medical context, half-life may also describe the time it takes for the blood plasma concentration of a substance to halve ("plasma half-life") its steady-state. The relationship between the biological and plasma half-lives of a substance can be complex, due to factors including accumulation in tissues, active metabolites, and receptor interactions.
Let's say that the half-life of Testosterone Enanthate is 14 days. (It may or may not be). This means that if you injected 500mg, then 14 days later, you would still have 250mg. It does not mean that 14 days after that you would have 0mg.
Imagine that you have a 1 liter container. You fill it with 500ml orange juice and 500ml water. You make a very small hole in the bottom, so that over the course of 14 days 500ml leaks out. At the end of 14 days, there will be 250ml each of water and juice. Add 500ml water and wait 14 days. Now you will have 125ml juice and 275ml water. Add 500ml water and wait 14 days. Now you will have 62.5ml juice and 437.5ml water. Add 500ml water and wait 14 days. You will now have 31.25ml juice and 467.75ml water. Top off with 500ml water and wait 14 days. Now after 5 half-lives, or 70 days, you are down to 15.625ml juice.
So after one 1/2, you are down to 50%, after 2x1/2, 25%. Then 12-1/2%, 6-1/4%. So it take 4 half-lives to be 94% clear. After 5 half-lives, you are 97% clear and this is when your blood and urine are considered "clean. So you can see that it also takes 4 or 5 half-lives to achieve a "steady-state" concentration. That is, for it to be eliminated as fast as it is building up.
I am going to present a simplistic model, close enough for illustrative purposes. Lets say 500 mg week Test E and a two week half-life, with once a week injections.
After one week you will inject 500mg (Injection #2), still having 375mg left from Injection#1(#1). After two weeks you will inject 500mg (#3), still having 250mg from (#1), and 375 from (#2). Three weeks = 500mg (#4) + 375mg (#3), 250mg (#2), 188mg (#1). Four weeks = 500mg (#5) + 375 (#4)+250(#3)+188(#2)+125(#1). So you see, after 2 half-lives, Injection #1 is @ 25%. By the time we get to week 10, or 5 half-lives we have 500+375+250+188+125+93+62+46+31+24+16(or 15.625 actually). You now have 1,710mg and will keep this "steady state" as long as you continue this dosing. You can see why the long esters start to "kick in" after several weeks. (You could always front-load with a couple grams a week the first two weeks.)
So, whenever you stop, you will have 1,710mg in your body. two weeks after that you will have 855mg. After 4 weeks, 427.25mg. After 6 weeks, 214mg test still hanging around. After two months you will still have over 100mg test E and this is more than "normal".
I hope this makes it more clear as to why an Aromatase inhibitor (AI) ran during post cycle therapy (pct) makes sense. And why merely blocking all this estrogen with a SERM such as nolva could conceivably lead to a rebound if discontinued too soon, and why some folks get gyno post-cycle. Personally, I feel the half-life of test E is probably closer to 10 days, but that would just mean it takes 50 days instead of 70 to build up to the steady state, and 50 days instead of 70 to be 97% clear. Either way, you're still talking supra-physiological levels well into post cycle therapy (pct) and beyond.
It also suggests to me that one could continue to sustain a higher volume training-wise, if that's what they were doing on-cycle, as you will still have considerable cortisol blockage for a good 3-4 weeks post-cycle with a long ester. After that I would decrease training volume to avoid a cortisol rebound eating at your gains.
hi everyone
im sure you all know roughy what the half life is of your favorite testosterone esters, and when to start post cycle therapy (pct) after your last jab.
Seen some important infomation about post cycle therapy (pct) start times, and I would like to know what you guys think whats your opinions on this?
Half-lives, AIs and post cycle therapy (pct)
--------------------------------------------------------------------------------
There has been recent discussion on this topic, and I thought more might be beneficial. The biological half-life or elimination half life of a substance is the time it takes for a substance (for example a metabolite, drug, signalling molecule, radioactive nuclide, or other substance) to lose half of its pharmacologic, physiologic, or radiologic activity, as per the MeSH definition. In a medical context, half-life may also describe the time it takes for the blood plasma concentration of a substance to halve ("plasma half-life") its steady-state. The relationship between the biological and plasma half-lives of a substance can be complex, due to factors including accumulation in tissues, active metabolites, and receptor interactions.
Let's say that the half-life of Testosterone Enanthate is 14 days. (It may or may not be). This means that if you injected 500mg, then 14 days later, you would still have 250mg. It does not mean that 14 days after that you would have 0mg.
Imagine that you have a 1 liter container. You fill it with 500ml orange juice and 500ml water. You make a very small hole in the bottom, so that over the course of 14 days 500ml leaks out. At the end of 14 days, there will be 250ml each of water and juice. Add 500ml water and wait 14 days. Now you will have 125ml juice and 275ml water. Add 500ml water and wait 14 days. Now you will have 62.5ml juice and 437.5ml water. Add 500ml water and wait 14 days. You will now have 31.25ml juice and 467.75ml water. Top off with 500ml water and wait 14 days. Now after 5 half-lives, or 70 days, you are down to 15.625ml juice.
So after one 1/2, you are down to 50%, after 2x1/2, 25%. Then 12-1/2%, 6-1/4%. So it take 4 half-lives to be 94% clear. After 5 half-lives, you are 97% clear and this is when your blood and urine are considered "clean. So you can see that it also takes 4 or 5 half-lives to achieve a "steady-state" concentration. That is, for it to be eliminated as fast as it is building up.
I am going to present a simplistic model, close enough for illustrative purposes. Lets say 500 mg week Test E and a two week half-life, with once a week injections.
After one week you will inject 500mg (Injection #2), still having 375mg left from Injection#1(#1). After two weeks you will inject 500mg (#3), still having 250mg from (#1), and 375 from (#2). Three weeks = 500mg (#4) + 375mg (#3), 250mg (#2), 188mg (#1). Four weeks = 500mg (#5) + 375 (#4)+250(#3)+188(#2)+125(#1). So you see, after 2 half-lives, Injection #1 is @ 25%. By the time we get to week 10, or 5 half-lives we have 500+375+250+188+125+93+62+46+31+24+16(or 15.625 actually). You now have 1,710mg and will keep this "steady state" as long as you continue this dosing. You can see why the long esters start to "kick in" after several weeks. (You could always front-load with a couple grams a week the first two weeks.)
So, whenever you stop, you will have 1,710mg in your body. two weeks after that you will have 855mg. After 4 weeks, 427.25mg. After 6 weeks, 214mg test still hanging around. After two months you will still have over 100mg test E and this is more than "normal".
I hope this makes it more clear as to why an Aromatase inhibitor (AI) ran during post cycle therapy (pct) makes sense. And why merely blocking all this estrogen with a SERM such as nolva could conceivably lead to a rebound if discontinued too soon, and why some folks get gyno post-cycle. Personally, I feel the half-life of test E is probably closer to 10 days, but that would just mean it takes 50 days instead of 70 to build up to the steady state, and 50 days instead of 70 to be 97% clear. Either way, you're still talking supra-physiological levels well into post cycle therapy (pct) and beyond.
It also suggests to me that one could continue to sustain a higher volume training-wise, if that's what they were doing on-cycle, as you will still have considerable cortisol blockage for a good 3-4 weeks post-cycle with a long ester. After that I would decrease training volume to avoid a cortisol rebound eating at your gains.
