If I give myself a shot of 1000 mg of testosterone; what is the active dosage amount after 10 days? The general answer everyone will state; is 500 mg. Thus we agree that the active ingredient diminishes daily. But the real question is; what is the active amount the day after the shot or even two or three days after? To answer this question we need to understand how half-life works in relation to pharmacology.

I’ve seen lots of talk about half-lives in different forums. I like to give my interpretation of how half-lives work when building a cycle. The popular understanding of how a half-life works is simply that if I were to give myself one injection of 1000 mg of testosterone enthenate then in approximately 10 to 10 ½ days it will be 500 mg active on my receptors. This would be entirely true if I were to give myself this one and only shot. But this is not how cycles are done we do not give ourselves one shot only, what we do typically is split the dosage up into two shots per week, this is relevant mathematically.

There is a mathematical principle called the law of half’s. This principle states that if you were to divide something in half and then divide it again and again you would never diminish it to zero. On a graph the line would be asymptotic never actually touching zero. Now don’t get caught up in the details of understanding this principle, what’s important is understanding that you will get close to zero and therefore it is understood that zero can be attained. Another way of looking at it is, if I’m standing in the middle of a room and I walked halfway to the wall and then half of that length and then half of that length I will never actually reach the wall. Now physiologically this is untrue we all know we can actually touch the wall but in chemistry and in pharmacology the dosage amount never actually reaches zero.

For the purposes of understanding I’m going to use round numbers and basic figures that we would actually use for a simple test cycle. I’m going to use a 10 day half-life and a five-day interval. An interval is the time period between shots. Most people use a Monday Thursday shot schedule. I believe this is not the most effective way and I will explain why. How does this relate to what I described above? The answer is simply that if I give myself a shot schedule of 500 every 10 days that I would take 250 mg every five days. Based on the mathematical principle of a Law of Halves I can expect that five days from my first injection the active amount to be 177 mg, now add to this 250 mg for the next injection day and the new amount is 427 mg. Five days later the active amount would be 302 mg add to that another 250 mg and we are now at 552 mg and so on and so forth. What’s going on is that each day we are dividing the amount that is actually in our system so the day after our first injection we are no longer dividing the amount of 250 we are actually dividing something like 235 and therefore the amount we are dividing five days after the first injection is 177 not 250. I think it’s best to divide the interval of shots into how much you want to actually have in your system based on the half-life you are using. What I’m saying is if you give yourself a shot on Monday then another one two days later on Thursday then wait three days later till Monday again you will not have a steady rise to the peak of your cycle. In my opinion it would be better to space your injections out by days and not days of the week. For example the five-day interval I used above which happens to be exactly half of the half-life. I’m not saying use a five-day interval what I’m saying is use the principle. Inject every three days or every four days but be consistent. And understand that by changing your interval spacing you change the amount that’s being divided on a daily basis. This is nominally understood by those who choose to inject a short ester on a daily basis or every other day. Obviously they realize that their strength gains and other side effects occur much quicker the closer their intervals are. But this is also a double-edged sword for those who frontload with too high of a dosage as the amount you think you have in your system can actually be much higher. This could result in a short rise to a peak followed by a plateau then drop to a lower plateau for the duration of the cycle until taper.

For those who want to research this themselves you start by looking up the term pharmacokinetics. The mathematics I used to formulate this model in Excel is as follows:
The elimination rate constant which is the rate at which drugs are removed from the body (ke)
ke = ln(2)/t1/2.

The elimination half-life is the time required for the concentration of the drug to reach half of its original value (t1/2)
T1/2 = ln(2)/ke

The loading dose abbreviated as D is the design parameter in this case 250 mg for the first shot.

The volume of distribution abbreviated as Vd is the volume in which a drug is distributed for all intent and purposes 6 L of blood.

When I design my cycles I chart them using these principles I shoot for the greatest peak in the longest plateau at that peak giving me the greatest area under the curve also known as AUC. To reach the largest peak it typically takes 4 to 5 half-life cycles before our bodies are in what is considered a maintenance dose. (This is why test takes 4 to 5 weeks to kick in). Soon I will post pictures of these graphs and their corresponding values. I will also post another topic on what an area under the curve is and why it is valuable to me in my cycles. I know this can be confusing and overcomplicated but I like to see how my cycles compare to my blood tests. It is my intent upon completion of my current cycle and PCT to report my numbers and their relationship to this model.

To sum up when pharmaceutical companies are developing new products they use mathematical models developed using pharmacokinetics. These models are based on the idea that the body has approximately 7 compartments. These compartments are the different vital organs that eliminate the drug in use at different rates. An even simpler model has only two compartments however, for our purposes we all use only one compartment model. We assume the entire body eliminates the gear we take at the same rate. The importance of these models is to calculate as close as possible proper dosage amounts for the drugs to be used before experimenting on human subjects.

I welcome any thoughts on this paper and how it pertains to the things we do on this site.
http://en.wikipedia.org/wiki/Pharmacokinetics