Half Life and Esters


There are several different esters associated with testosterone. The two that we will discuss are cypionate and enanthate, which are two of the most popular in TRT and bodybuilding. The half life of cypionate is 12 days, and Enanthate's half life is 10.5 days.
The half life concept might seem a hard thing to understand, but it is very simple. Let's take as an example the cypionate ester with a 12 day half life. It means that if you inject 500 milligrams (mgs) of the hormone, 12 days later half of this particular injection will be leftover in your blood system, which is 250mg; furthermore, in another 12 days half of that will be gone away, leaving just 125mg, and so on.
Doctors typically use testosterone cypionate when prescribing TRT because of its slightly longer half life, which allows the user do injections less frequently. It is quite logical because many patients have a hard time handling injections every day or every couple of days.


Use as a base Steroid in cycles


Many bodybuilders like to use testosterone cypionate or enanthate as a base for their cycles, and stack additional steroids on top. An example of this is stacking 500mgs of testosterone a week with trenbolone, deca durabolin, equipoise, anavar, dianabol, etc. It is important to remember that more hormones means more side effects, and that if you stack testosterone with another aromatizing compound you will experience a greater estrogen increase. Hence, it is important to use an aromatase inhibitor (AI), like Aromasin or Arimidex, to prevent any estrogen related complications. Contrary to popular opinion, you do not always need to run testosterone as your base in a cycle.


Dosages


The typical moderate testosterone dosage on a steroid cycle is 500mgs per week, with some users going up to a gram or more. Both cypionate and enanthate are usually injected every 5-6 days or so. Those on TRT will run around 150-200mgs per week because, for them, the goal is to get their testosterone levels within the normal range.


Which ester is better?


Aside from slightly different half lives, with cypionate half life being slightly longer (by 2.5days), the differences aren't that great.