Study: pharmacokinetics

All research was taken two ester nandrolone – decanoate and phenylpropionate. But the first took part in the experiment in two “hypostases”: the concentration of the active substance in a solution of 25 mg/ml and 100 mg/ml, although the amount of the active substance in all cases was introduced in the body is the same, 100 mg. Injections of the phenylpropionate (concentration 25 mg/ml), and the first “incarnation” was performed decanoate into the gluteal muscle, the second – and in the gluteus muscle and in the deltoid.

Original article in The Journal of Pharmacology was accompanied by a chart clearly showing the change in the concentration of nandrolone in the blood. I processed it a bit and let me quote here – I hope the authors will bear with me.

the graph shows that the concentration of nandrolone after injection of the phenylpropionate increases very sharply, reaching a peak of almost within a few hours.

NandroloneIndeed, those who used the “phenyl”, note that it starts working almost instantly. The maximum is reached, however, at the end of the day, then the concentration of nandrolone in the blood is on the decline.

Interestingly, in the case of nandrolone decanoate, the maximum concentration was achieved within a day after injection, although the growth here will be more fluid. But this happens only after the injection of the more concentrated solution, and only in the gluteal muscle. When injecting a less concentrated solution, and with injections in the deltoid muscle, the concentration is growing more slowly and the peak is reached only by the fourth day, and then at some later date.

the Peak after the injection in the case of phenylpropionate is very high – it exceeds the peak after the injection of decanoate is approximately 2 times. But to maintain this level of injection needs to be more frequent (about every 3-4 days), which will lead to a doubling of the weekly volume of nandrolone. At the same time, it is obvious that there is no point in giving injections of the phenylpropionate in a day, the more meaningless daily injections.


If the pharmacokinetics is the study of chemical transformations of drugs in the body, pharmacodynamics is the science about the mechanism of action of drugs on the body. In this case, the mechanism of action is meant the effect of nandrolone on the secretion of testosterone and inhibin – non-steroidal factor, suppressing the secretion of follicle stimulating hormone (FSH).

As can be seen from the graphs, nandrolone is highly suppressed secretion of endogenous testosterone, regardless of ester, concentration and site of injection. Recovery after a single injection (I emphasize – we are talking about a single injection, and a very small amount) took place relatively quickly – in the case of phenylpropionate testosterone came out at the same level of about 15-16 day of, in the case of decanoate is approximately thirty day.
Inhibin is also slightly reduced (most noticeable in the case of the injection solution of nandrolone decanoate with a high concentration of active substance in the gluteus muscle), but again thirty day returned almost to the previous level.

Some insights

First, the pharmacokinetics of nandrolone esters it is possible to move and esters other injectable AAS – testosterone, boldenone, etc. secondly, having data on the work of the phenylpropionate and decanoate, you can try to predict the behavior of other esters.

Phenylpropionate refers to the “short” esters (although essential chain and very heavy). In a similar way is acting propionate and cypionate – cyclopentylpropionate. But there are several features: concentration of drug in the blood after injection of propionate would fall more sharply after injection of cypionate curve first goes down, then stabiliziruemost and will stay at more or less the same level up to 7-8 days.

Behavior enanthate is very similar to the behavior decanoate, however, the peak will be slightly higher, but the drug will begin to leave the body.

In the end, it is immaterial which of the esters used in the long run you will get about the same level of drug in the blood. The peak concentration will be much higher in the case of “short” esters – the fact you can use either to pre-load, or making the injection a few hours before a workout (locally).

As local injections: the increase of the level of nandrolone in the blood when injected into the deltoid muscle was less rapid; peak concentration was the lowest.

Finally, you should pay attention to such interesting fact: the secretion of inhibin under the influence of nandrolone for some time reduced. Exactly the same was noted in other studies and in the case of testosterone. That is, small doses of AAS contribute to the normalization of spermatogenesis. This property is used in medicine to increase the level of FSH is often prescribed “Andriol” (testosterone undecanoate), “Proviron” (mesterolone), a small dose of testosterone enanthate or nandrolone decanoate. But that in small doses would be considered a drug, and their increase could easily turn into a poison.