Half life math question?

[BamBam54]

If a product has say a 24 hour half life, what happens with levels over time if you take the same dose at the same time every day? I keep hearing two different versions of what happens...


Do the "halfs" steadily build to ever increasing levels over time, or is each "half" replaced to stay at the same level over time?

 

[Renew1]

If a product has say a 24 hour half life, what happens with levels over time if you take the same dose at the same time every day? I keep hearing two different versions of what happens...


Do the "halfs" steadily build to ever increasing levels over time, or is each "half" replaced to stay at the same level over time?

At the end of the half-life (in this case, 24 hours), the amount of the compound is cut in half. And then at the end of 48 hours that HALF would be cut in half. ...and so on.

In order to figure how it is building up in your body, you would need to apply this to each dose, and keep track of the whole, the half, the half-halfs, and so on.
But for most of us (for most compounds) we don't find this necessary. We just select the compound we want to run, the dose we want to run, and look at the half-life only to determine how often we should dose. (Normally).

 

[BamBam54]

So if I have his right, a 24hr half life dosed every day will mean you are soon carrying double the starting dose for the duration, but not continuing to escalate beyond that to unlimited crazy levels. See attached spreadsheet

 

[Renew1]

Yep, but keep in mind... All of these thousands of posts from guys reporting upon the results, effects, and side effects .... They are all reporting based upon the dosages they are taking, not the amount that has built up in their bodies.
I just think you are probably making this more complicated for yourself than you have to.

 

[SouthPawSD]

So if I have his right, a 24hr half life dosed every day will mean you are soon carrying double the starting dose for the duration, but not continuing to escalate beyond that to unlimited crazy levels. See attached spreadsheet

Yes that would be correct math. Like states the only reasons I have ever seen is to know how often to dose in order to maintain and steady levels as possible, or in some cases for drug testing to get a rough estimate of when the compound would be undetected. Also now that I think about it this is where front loading would come into play I would assume.

Just curious what made you ask this question? It always interests me what Sparks questions for others. For me it was to avoid detection times in this question ha.

 

[HIT4ME]

Just FYI - half life is not a reliable means of avoiding detection times. A lot of tests look for metabolites which can remain in your system loooong after the parent compound has been metabized.

The math is essentially correct - if dosing 1x per half life (1x every 6 hours for a compound that has a 6 hr half life or in this case 1x every 24 hours with a 24 hour half life) will yield peak levels that eventually equal twice the dose, assuming instant and complete absorption.

The key here is that you get to a point where the amount you burn in between doses is equal to the dose you are taking. Or in this case, you have to have 2x the dose to burn through half of it in between doses - if that makes sense.

If you are dosing at a rate other than 1x half life (like 3x per half life or 0.66x per half life) the math gets more interesting.

For instance, there is a drug that can't be mentioned on this site that is rumored to have a half life of 36 hours, with 1x per day dosing usually. It is typical to have steady state levels of approx. 3x the dose in that scenario.

And the pharmacodynamics can slightly change things as well. If something absorbs over time, you may start metabolising a certain amount of it and then digest more, increasing the amount in the system which also increases the burn rate. But this gets more complex than I think you really need for most compounds.

So, short answer - your math is accurate and you seem to get it.

 

[SouthPawSD]

Just FYI - half life is not a reliable means of avoiding detection times. A lot of tests look for metabolites which can remain in your system loooong after the parent compound has been metabized.

The math is essentially correct - if dosing 1x per half life (1x every 6 hours for a compound that has a 6 hr half life or in this case 1x every 24 hours with a 24 hour half life) will yield peak levels that eventually equal twice the dose, assuming instant and complete absorption.

The key here is that you get to a point where the amount you burn in between doses is equal to the dose you are taking. Or in this case, you have to have 2x the dose to burn through half of it in between doses - if that makes sense.

If you are dosing at a rate other than 1x half life (like 3x per half life or 0.66x per half life) the math gets more interesting.

For instance, there is a drug that can't be mentioned on this site that is rumored to have a half life of 36 hours, with 1x per day dosing usually. It is typical to have steady state levels of approx. 3x the dose in that scenario.

And the pharmacodynamics can slightly change things as well. If something absorbs over time, you may start metabolising a certain amount of it and then digest more, increasing the amount in the system which also increases the burn rate. But this gets more complex than I think you really need for most compounds.

So, short answer - your math is accurate and you seem to get it.

Oh yes good point on the detection times. I didn't finish my thought on that but you did for me. Ya I was so confused at how people failed with short detection times then learned about metabolites.

Lol @ "drug that can't be mentioned"

 

[BamBam54]

The reason I initially asked was because I had concerns that due to the half life I was steadily increasing accumulated dose to dangerous levels in a longer cycle - ie 12 weeks vs 8 weeks. But turns out in my case it never gets beyond 2x initial daily dose, so good news there.