Frequency of Administration

Frequency of Administration -
Testosterone & Nandrolone
by Michael Mooney
from Volume 1 Issue No. 4 (Updated with link to studies May, 2001)

Frequency of Administration - Testosterone Cypionate/Enanthate

Testosterone is most commonly used in the United States as the cypionate and the enanthate esters. Doctors often administer both forms of testosterone as infrequently as every two weeks and in some cases every month because of misinformation about the frequency of administration in the Physician's Desk Reference.

I have consistently heard people who are given these forms of testosterone complain of a large decrease in energy, libido, clarity of thought, and mood, by the time the two or four week administration occurs. An analysis of the published literature that details the pharmacokinetics of these drugs show that this is inappropriate if the most consistent blood-levels of the drugs are desired. 

One study stated that 140 mg. of testosterone cypionate and testosterone enanthate produced similar blood levels after injection, and stated that heightened blood levels decreased to basal levels by day ten.1 With higher doses the duration appears to increase a little as another study stated that with an injection of 200 mg. of testosterone cypionate blood levels reached basal levels by days 13 to 14.2

Looking at the chart, it is easy to see why a person would feel a large decline in energy, libido, stamina, mood, and overall quality of life with two or three week dosing, so I urge the physician to consider adjusting dosing strategies. I consistently see people experience the greatest quality of life improvement when testosterone cypionate or enanthate are administered once every seven days.

Source: Schulte-Beerbuhl, 1980

There are forms of testosterone that are not available in the United States that are designed to provide longer duration of release. These products, which include Sustanon and Durateston, are typically blends of longer and shorter acting testosterone esters that release more gradually. They provide a more consistent release with less peak/trough effect than cypionate/enanthate.

Frequency of Administration - Nandrolone Decanoate (Deca Durabolin)

Pharmacokinetic studies with nandrolone decanoate also show that it is more desirable to administer it on a weekly basis rather than bi-weekly or monthly if the most consistent blood levels of the steroid are desired. 

While blood levels of nandrolone rise in several hours, the mean half-life of the nandrolone decanoate is approximately 20 percent longer than testosterone cypionate. 

Note that dosing information in the package insert for nandrolone decanoate recommends weekly administration. The package inserts for testosterone cypionate and testosterone enanthate should be updated, as these forms of testosterone have an even shorter lifespan in the body than nandrolone.

Note that with oil-based steroids like the testosterones and nandrolone there can be a pool of the drug that accumulates in the injection site area that lengthens the decline in blood levels somewhat after several injections. Still, after watching many people over the last several years, I have seen that for most consistent blood level of the drug and best overall patient quality of life, weekly administrations work best.


  1. Schulte-Beerbuhl M et al., Comparison of testosterone, dihydrotestosterone, luteinizing hormone, and follicle-stimulating hormone in serum after injection of testosterone enanthate or testosterone cypionate. Fertility and Sterility (1980) 33.2 : 201-203.

  2. Nankin HR, Hormone kinetics after intramuscular testosterone cypionate. Fertility and Sterility (1987) Jun; 47.6 : 1004-1009.

  3. Wijnand HP et al., Pharmacokinetic parameters of nandrolone decanoate to healthy volunteers. Acta Endocrinol Suppl (Copenh) (1985) 271 : 19-30.

If your doctor won't consider prescribing weekly testosterone injections, print this article and the contents of this link out and share it with your doctor.

Disclaimer: This article is provided for educational purposes only, and is in no way a substitute for the advice of a qualified medical doctor or a recommendation to do other than your doctor determines is best for you. You should present this information to your doctor for their analysis because appropriate medical therapy and the use of pharmaceutical compounds like anabolic steroids should be tailored by a knowledgeable doctor for the individual as no two individuals are alike. I do not recommend self-medicating with any pharmaceutical drug as you should consult with a qualified medical doctor who can determine your individual situation. If you use the information I present without the approval of your doctor, you do so strictly at your own risk and no responsibility is implied or intended on my part.

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