T Nation

Half Life Calculations

Yeah absolutely you can graph this stuff. My point still is the graph is only accurate if you have an accurate assessment of what the half-life is.

ya, i would go with the carbon length by 0.7 too… i remembered you mentioning the equation, and i was very intrigued but for the life of me couldnt remember it! i only got my numbers from:

http://www.muscletalk.co.uk/article-steroid-half-life.aspx

and i never expected a programmer to pop in and make some database from it! lol!

Tell you what, i really CANNOT be bothered to write up a new one, even though a 2 day HL would be easier…!

JJ

That muscletalk link says that the half-life of TA is 3 days. Common wisdom around here says to pin TA every day. Is that wisdom based on anecdotal evidence?

[quote]kansas wrote:
That muscletalk link says that the half-life of TA is 3 days. Common wisdom around here says to pin TA every day. Is that wisdom based on anecdotal evidence? [/quote]

Yeah I was wondering about this. I strongly suspect that their site is simply wrong.

Using the .7 calculation, Tren A has 2 carbon atoms so the half life is 1.4 days therefore ED injections are required to maintain a reasonable level.

No idea where they’ve got 3 days from.

[quote]saps wrote:
Sentinal wrote:
Or am i just confusing myself?

No you’re confusing me too :wink:
If you shoot 100mg [forgetting the ester weight] of whatever and it has a four day half life lets say than after 4 days you’d have 50mg left and after 8 days you’d have 25mg left and so on and so forth[/quote]

My point is that without carrying out a controlled experement where in-vivo test concentrations are measured at least daily, the concentration of a compound that obeys first order rate kinetics (most biologically active compounds) can only be accurately measured in divisions of its half life.

This would mean that from a one-off injection of test e, with a theoretical half life of 5 days, you could calculate the amount of remaining compound on days 0,5,10,15 etc, but not on any other day without knowing the the value of K i talked about in my prevoius post.

Someone please correct me if i’m wrong!

[quote]Sentinal wrote:
My point is that without carrying out a controlled experement where in-vivo test concentrations are measured at least daily, the concentration of a compound that obeys first order rate kinetics (most biologically active compounds) can only be accurately measured in divisions of its half life.

This would mean that from a one-off injection of test e, with a theoretical half life of 5 days, you could calculate the amount of remaining compound on days 0,5,10,15 etc, but not on any other day without knowing the the value of K i talked about in my prevoius post.

Someone please correct me if i’m wrong![/quote]

Sentinal - you are right. The concentration of AAS on any given day between half life divisions is not exactly a division of that half life.

100mg of a 4 day half life ester will indeed be at 50mg on day 4, but at day 1 it will not be at exactly 1/4 of the difference between day 1 and 4. If a graph was drawn using daily tests of drug level in the blood it would be curved.

So by using this block method we end up with a curved graph made up of straight lines in 4 day blocks (or whatever the half life is).

Programatically this gives me a couple of problems.

1 - It’s not very accurate (but is it accurate enough?)

2 - If I use this block method then for very short esters (acetate specifically) I’m going to have to calculate in blocks of half days as it would make the results too inacurate to round the half life up or down to a single day. This again comes down to accuracy - can I round the acetate ester to 1.5 days even though it’s actually 1.4? In this case I suspect that it would be close enough.

If I use this method then I’ll calculate all esters in half days as it would be daft to write extra code to handle half life values for whole days.

It’s either that or calculate the curve of the decay of the ester given the half life length. This would be more accurate I suspect but would it be worth it? I’m tempted to say no - if for no other reason than my brain hurts trying to figure out the math behind it.

Sentinel - If you can help me out with an equation…?

No, that isnt far off (i havent done saps equation mind you but…) ED makes sure the blood levels is kept steady, EOD is ok too… if the half life is 3 days you would want to inject on a more frequent basis than 3 days correct?

So assuming 3 days is correct, then ED or EOD injections is what is required.

JJ

maybe here…

this one says 1-2 days but that isnt measured (anec.)

mesomorphosis.com/steroid-profiles/trenbolone.htm

I think that one os by shudder A.Roberts…

Lol!

[quote]Renton wrote:

Sentinel - If you can help me out with an equation…?
[/quote]

Assuming the decay of test in the body follows a first order reaction then:

(ln)A = -KT+(ln)Ao

where K is the rate constant
(ln)A = ln concentration
(ln)Ao = ln initial concentration

Therefore a plot of ln[A] vs. time t gives a straight line with a slope of - k.

Knowing K allows you to find the concentration of your compound at any value of t.

But yes, your method of using given half lives to construct a suitable curve would be accurate enough for longer estered test variants.

[quote]Sentinal wrote:
Renton wrote:

Sentinel - If you can help me out with an equation…?

Assuming the decay of test in the body follows a first order reaction then:

(ln)A = -KT+(ln)Ao

where K is the rate constant
(ln)A = ln concentration
(ln)Ao = ln initial concentration

Therefore a plot of ln[A] vs. time t gives a straight line with a slope of - k.

Knowing K allows you to find the concentration of your compound at any value of t.

But yes, your method of using given half lives to construct a suitable curve would be accurate enough for longer estered test variants. [/quote]

Cheers Sentinel - I’ll have a play around with that.

Hope this shows up Ok. Here’s a 4 day half life ester using the 1/2 day block method graphed out.

[edit] Click it for a slightly larger image - you can make out the linear 4 day blocks that go to make up the curve.

[quote]Renton wrote:
Hope this shows up Ok. Here’s a 4 day half life ester using the 1/2 day block method graphed out.

[edit] Click it for a slightly larger image - you can make out the linear 4 day blocks that go to make up the curve.[/quote]

Are you sure the half life isn’t 7 days?

[quote]Sentinal wrote:
Renton wrote:
Hope this shows up Ok. Here’s a 4 day half life ester using the 1/2 day block method graphed out.

[edit] Click it for a slightly larger image - you can make out the linear 4 day blocks that go to make up the curve.

Are you sure the half life isn’t 7 days?[/quote]

Sentinel - Sorry I missed your post - The graph was generated from some test data and the axis turn out to be a bit screwed. The curve and dose is for a 4 day half life ester though.

Update:

I’ve completed quite a bit of the code to do a block style calculation - enough in fact to test in a live environment.

The system produces either a standard (day / peak level) list or a verbose (day / peak (peak calculation)) table.

I’m just working on uploading it and setting up the online database of ester half lifes then I’ll post up the URL.

Ok - Here we go - Beta 1.

It’s a bit rough but it seems to work. I’ve not done any manual testing but the calculations look about right so far.

I’ll do some tests tomorrow but in the mean time if anybody else would like to check out my math and see if it adds up it would be appreciated.

http://www.jmit.co.uk/PeakAASCalculator/tabid/64/Default.aspx

Lotta leg work Rents nicely done. I do like the ability to change the values around

[quote]saps wrote:
Lotta leg work Rents nicely done. I do like the ability to change the values around[/quote]

Cheers Saps.

I’m going to find some time to properly test it (although from initial tests it gives the correct results). I want to make sure though.

Once that’s done I’ll get it to generate a graph too and maybe do some sort of export facilities.

I used the half life values from other sites too so I want to check on those. The .7 method is very useful for this but to be able to do the calculation in blocks I’ve had to restrict half life values to whole or half day increments.

Close enough for this purpose I suspect.

Its ok like I said you can totally change the values to whatever you want. For instance you select Enanthate as your ester and you get 10.5 days. I just change that to 5 and went on my way

Looking real good so far, Rents.

I only played with it for a few minutes, but haven’t found any incorrect values.