T Nation

Steady Levels... Is It Worth It?

Your body produces different levels of testosterone at different times of day and it’s not the exact same amount on a day to day basis depending on sleep , alcohol consumption etc …

So why is it the golden rule to inject the same amount , at the same time , each time (whether it’s daily , 3.5 or once a week ) you inject for 6 weeks ??

That’s not how we naturally produce testosterone …

When you are injecting T-cypionate you are essentially using a medicine which has a half life, cypionate has a half life of 7-8 days, you don’t have access to all inject T right away, only a small portion of it.

The rest become available later and as you inject into the coming weeks, that which was not previously available is at 6 weeks because you are stacking the half lives on top of each other and now you have twice the medicine in your system than you have at the start.

It would be no different if on an SSRI, we are still dealing with half lives. Naturally produce testosterone has a very short half life (10 to 20 minutes) and is bioavailable immediately, that’s how levels can be high in the morning and lower at 12 noon.

A stable state is reach when there is a consistent dosage injected for at least 6 weeks. If T-cypionate has a half life of 10-20 minutes, you would have to inject every 10-20 minutes.

It still fluctuates, but you are trying to control he range with consistent timing.

My thing is if you inject 90 mgs one day and 100 mgs 3.5 days later etc for 6 weeks is one really not gonna have stable levels ?

Injecting T is not natural in any way. You can not mimic your natural production. T cyp takes 40 days to reach a steady state in your blood it really doesn’t make any difference if you inject 30 one day 50 the next.


T cyp and T enant have an average half life of 3.5 to 4 days (high intersubject variability. Its a general concept in pharmacology that in multidosing steady state levels are reached after 4 to 6 half life of the molecule, ie for T cyp and enant its about 3 weeks. But thats reaching constant serum levels and it should not be confused with the pharmacodynamic response (the action oc the molecule, ie also how you feel).

Yes its correct thaf T levels fluctuate quite substantially over the day (diurnal variability), thats why - purely from a PK perspective - dermal T best mimics the natural fluctuation… With T enant or cyp mimicing this variability during the day iy not possible due to the half life. It different with T prop, but you have to inject more frequently.
Interestingly this diurnal variability gets weeker as you age.

regarding PK read Behre et al., 2006 Pharmacology of testosterone preparations

So one person says half life if 7-8 days other says 3-4 days … which is it ?

A quick google search says 8 days , so where u coming up with 3-4 days ?

@straightnasty Thats why if you inject ED you dont bother with that

Reality is, most guys do just fine on weekly or twice weekly. Some guys do alot better on EOD or ED but this comes down to the individual.

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it’s about 4 days according to scientific studies. Read the above mentioned literature and you will get the answer.

You can also take a look at Figure 14.8 from the link below which show the PK profiles of T enant and cyp

If you don’t have access at least look it up on Wikipedia

For reference, testosterone enanthate has an elimination half-life of 4.5 days and a mean residence time of 8.5 days and requires frequent administration of approximately once per week.[14] Large fluctuations in testosterone levels result with it, with levels initially being elevated and supraphysiological.[14] The pharmacokinetics of testosterone cypionate have been studied and reported.[15]

Is that what your doing now ?

I can read many different studies , some say 8 days some say 4 days …

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Again lol

Show me a single scientific PK study that resulted in an average half life of T enant or cyp of 8 days. Evidence please and not just plain statements followed by …

Here is one from the FDA. Test C half life = ~8 days.

And yes, it is a pharmacokinetics study.

BTW, this is the first I have heard 3-4 days. Be careful reading one study. I have heard 10 days and 7-8 days.

Thank you !!!

There ya go Johann777 , take your lol shit somewhere else clown

You will accomplish nothing, it’s not going to provide the results you are looking for and just complicates your protocol. It’s a small change in ones protocol plus or minus 10mg difference and I just don’t see how your body is going reap any benefit.

Because you are on synthetic and the body cannot create T when it needs it. So we try to keep levels as stable as possible so the body always has what it needs. It’s also harder for new trt patients to find relief if their levels are fluxing too much.

We peak 1-2 days after injection. Depending on Ester there is T available for use right away. The rest is slowly released. You don’t want the half life of one shot. You want to know how many days it takes to stabilize and keep the stability of serum levels.

When you inject 200mg ast once the body was not built to utilize that and that’s why it’s usually easier to do daily for most. Unless you compensate with ai and etc. even then some folks have zero issues once weekly.

I’m a bit lost as to why this matters. You can not compare synthetic T with natural t production. Therefore you give the body a consistent amount.

Daily injection with a long ester only has the effect of tight control on how much Free is hitting short term, it reduces spikes, but long term your levels are going to be your levels as it accumulates over half-lives. You’re not mimicking anything, you’re limiting how high you spike post injection. Really not the best use of a long ester. If you want or need that spike control, you really should be on cream or test prop.


Dude thats the patient leaflet. Show me the original data. A study published in a peer reviewed medical journal. I will collect all the availabke PK data and post it later, there is plenty of it.