Testosterone Cypionate and Testosterone Enanthate: The Real Facts

Posted by Dr. Michael White, Updated on May 15th, 2024
Reading Time: 7 minutes

If you are considering giving injectable testosterone a try, you need to know as much as possible before plunging in and taking that first step.

Keep reading.

This brief article will provide you with the basics: a look at the science as to how testosterone works, the difference between Cypionate and Enanthate, recommended dosages, and potential side effects.






Testosterone Esters

Much of the testosterone prescribed for testosterone replacement therapy is in the form of testosterone "esters."

An ester is merely a name for a chemical compound that forms from a reaction between a carboxylic acid and alcohol.

A simple chemical diagram of this result is shown below in Figure A.

Figure B shows the chemical structure of free testosterone (chemical formula C19H28O2) as well as two different esters of testosterone (testosterone cypionate and testosterone enanthate).

There are many different esters of testosterone, but here we will only be discussing two of the most commonly prescribed injectables: testosterone enanthate and testosterone cypionate.

Each of these various esters is a molecular chain composed of carbon, hydrogen, and oxygen atoms.

The main difference between the different esters is how many carbon and hydrogen atoms make up the chain.

For example, the propionate ester is composed of 3 carbons, six hydrogens, and two oxygens, whereas the cypionate ester consists of 8 carbons, 14 hydrogens, and two oxygens.

To improve the solubility of testosterone in oil, the substance undergoes a process called esterification, which also slows the release of the testosterone from the injection site.

Testosterone, in its free, non-esterified form, has poor solubility in either oil or water, though it can be suspended in water.

Non-esterified testosterone is available in an aqueous injectable form with the drug name "Aquaviron."

However, this type of testosterone only stays active in the body for a brief period (a matter of hours).

Because of this, it must be injected daily to maintain a continuous level of testosterone in the blood.

Therefore it is rarely used for testosterone replacement therapy as an injectable.

Once you have added an ester group to testosterone, it becomes even less soluble in water and more soluble in oil.

Usually, the more carbon atoms there are in an ester, the more soluble the ester is in oil.

For example, testosterone propionate (with three carbon atoms in the ester group) is less soluble in oil than testosterone cypionate (with eight carbon atoms in the ester group).

However, this is a general rule; the solubility of a molecule depends on structural factors that are beyond the scope of this article.

So generally, the more carbons the ester group has, it becomes more soluble in oil and less soluble in water.

The term for this ratio between oil and water solubility is called the "partition coefficient," that is, the higher the solubility in oil, the higher the partition coefficient.

Why is this important?

Because the partial coefficient affects how long the drug itself stays in the system.

If the testosterone transfers too quickly from the oil to the blood, the result is a sudden spike in testosterone which then rapidly drops once the dose has been used up. This is not the desired result.

The slower-acting testosterone is, the better.

Testosterone cypionate has a high partition coefficient.

When injected, the drug remains in its esterified form once it enters the muscle tissue.

From there, it will slowly enter the circulation as it is picked up in small quantities by the blood.

Once the esterified testosterone is brought into the bloodstream, "esterase enzymes" tear off the ester chain in a process known as "hydrolyzation."

This leaves the testosterone in its free form to execute its different actions and effects.

When a particular testosterone ester is "fast-acting" or "slow-acting," it usually refers to the partition coefficient/solubility in oil.

As described above, esters with more carbon atoms will be more soluble in oil; they are often referred to as "slow-acting" esters (they stay active in the system longer).

Esters that are less soluble in oil are often referred to as "fast-acting" forms of testosterone, referring to the fact that they are more quickly available and used up in the bloodstream.

For men who are using injectable testosterone, slow-acting esters tend to be preferred, as fewer injections are needed as time passes to keep the blood levels of testosterone reasonably constant.

Testosterone enanthate (7 carbons) and testosterone cypionate (8 carbons) both take about 8-10 days to be fully released into the system and so they are typically injected once every 7-14 days.

Testosterone propionate (3 carbons) takes about 3-4 days to be fully released in the system and must be injected in smaller doses at least weekly if not twice weekly.

Dosage Amount and Frequency

The dosage amount and timing for injectable testosterone will depend mainly upon which ester is used, as well as the individual's response to the hormone. In general, dosages will vary between 50 mg and 300 mg per injection, depending on the ester and the dosing regimen.

An average injectable dose is about 200-250 mg every two weeks, though many men inject 100 mg every week or every ten days, or other variations depending on their own bodies' needs and sensitivities.

Again, the exact dosage required will vary from person to person, and health and well-being should be carefully monitored while determining an individual's ideal dose.

Testosterone esters are typically suspended in either cottonseed oil or sesame seed oil.

Some people find that they may have an allergic or skin reaction to one of the oils.

Individual brand-name testosterone esters are mass-produced using one oil or the other (as noted below), but by using a compounding pharmacy, you can have any testosterone ester suspended in your choice of oil (with a proper prescription).

As always, discuss this with your prescribing physician.

Testosterone Enanthate: Chemical formula C26H40O3

Testosterone enanthate is one of the primary forms of testosterone prescribed to men in the United States.

It is a slow-acting ester with a release time of 8-10 days.

The name-brand of testosterone enanthate available in the United States is called "Delatestryl," which is suspended in sesame oil.

Testosterone enanthate is typically injected anywhere between once every week to once every two weeks.

Generic testosterone enanthate can also be obtained through a compounding pharmacy; such stores can mix testosterone enanthate in sesame, cottonseed, or any other appropriate oil.

Some physicians combine individual esters for patients since this may give better blood level distribution, although no studies have been done in the United States using ester blends.

Testosterone Cypionate: Chemical formula C27H40O3.

Testosterone cypionate is the other primary injectable form of testosterone prescribed to men in the United States.

It is a slow-acting ester with a release time between 8-10 days, similar to that of enanthate.

The name-brand of testosterone cypionate available in the United States is called "Depo-Testosterone," which is suspended in cottonseed oil.

Testosterone cypionate is typically injected anywhere between once every week to once every two weeks.

Like testosterone enanthate, testosterone cypionate can also be obtained through a compounding pharmacy; such stores can mix testosterone cypionate in sesame, cottonseed, or any other appropriate oil.

Some doctors like to prescribe 300 mg every three weeks, but many believe that this amount accentuates the peaks and valleys of testosterone blood levels a lot more than the most commonly used dose of 100 or 200 mg every two weeks.

Cypionate is the drug of choice for many men, especially athletes and bodybuilders.

This is due to its quick anabolic (muscle-building) action. It is capable of giving increases in size and strength and doing it quickly.

In the worlds of powerlifting and football, it is not uncommon for athletes to use as much as 2000-4000 mg per week!

This can lead to aberrant and aggressive behavior.

Most of the men using these mega-doses are only concerned about increasing their size and strength, not their health. Also, they don't mind being aggressive jerks.

At this mega-dose level, users can be a danger, not only to themselves but everyone else as well.

These high doses can also result in many nasty side effects: hypertension, baldness, acne, and liver damage.

It is only moderately toxic to the liver, but when abused it can wreak havoc on the body's endogenous production of testosterone.

One would think that even the stupidest athletes know this, but they just don't care. They want strength, and the consequences are ignored.

However, when used correctly, under the direct care and supervision of a physician that is knowledgeable about testosterone, this should not be a problem.

Follow the instructions of your doctor, and do not exceed the dosage on your own!

Which form of testosterone should I use?

It's not a big deal.

Some users say that enanthate lacks the power of cypionate, but most men cannot differentiate between the two.

They are both usually injected in the same time frame, and unless you have a known sensitivity to water retaining drugs, they are indistinguishable.

If you do keep water, enanthate would be the best choice. Discuss this with your physician.

A warning about increasing your T dosage

When beginning TRT, some men may feel impatient while waiting for changes to happen.

Some even consider doubling or tripling their dose, mistakenly thinking this will speed up the process. As previously mentioned, DO NOT DO THIS!

In fact, increasing your dose might have the effect of slowing your changes. This is because excess testosterone in your body can be converted into estrogen by an enzyme called "aromatase."

This conversion is part of the body's natural feedback system: if there is an abundance of testosterone in the body, it is converted ("aromatized") to estrogen to maintain a "normal" hormonal balance.

Therefore, taking massive doses of testosterone is not the road to go. Testosterone replacement, when done correctly, is a long-term project.

And that is precisely how our clinic approaches testosterone therapy. We will ensure that your testosterone therapy is done safely and correctly. Contact us.


Beyond testosterone cypionate: evidence behind the use of nandrolone in male health and wellness.


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