Testosterone Suspension is an injectable consisting of pure testosterone micro-particles suspended in water.
It is considered the most potent injectable testosterone available.
Being non-esterified, it becomes active immediately upon injection, and its high testosterone content per 1mg makes it significantly more potent.
Esterified testosterones (e.g., Enanthate, Cypionate) require ester cleavage for activation, meaning it takes several weeks for their effects to manifest.
For example, while Enanthate typically shows muscle and strength gains around 4-5 weeks later, Testosterone Suspension can produce noticeable effects within the first week, with most benefits achieved within a 4-week cycle.
This means Testosterone Suspension is advantageous for rapid mass and strength gains due to its fast action and high efficiency.
Testosterone Suspension is the oldest anabolic steroid, first synthesized by German scientists in the 1930s, developed much earlier than esterified testosterones.
Despite more severe injection pain and a shorter half-life requiring daily injections compared to later-developed Testosterone Propionate (mid-1930s) and Enanthate (1950s), it remained very popular.
This formulation was widely sold under various brand names, primarily used for treating hypogonadism and male menopause, and rarely for female breast cancer.
However, after Steris Laboratories discontinued its production in 1998, it became a rare drug in the US prescription market and is now only available through veterinary or special order channels.
The advantage of Testosterone Suspension is that it contains no ester, providing rapid effects, and it is manufactured worldwide in various dosages and concentrations.
It is typically available in 1ml ampules or 10ml vials.
Chemical Properties of Testosterone Suspension
Testosterone Suspension is an injectable consisting of pure, unaltered free testosterone in a microcrystalline form suspended in water.
The absence of an ester bond results in a half-life of 2-4 hours (some studies report up to 24-39 hours).
This product contains no esterified carboxylic acid, meaning the testosterone content per injected 1mg is significantly higher than other formulations.
For example, 100mg of Testosterone Suspension delivers exactly 100mg of testosterone, whereas 100mg of Testosterone Enanthate yields only about 70mg of testosterone after ester removal.
Properties of Testosterone Suspension
Testosterone promotes nitrogen retention in muscle tissue, significantly increasing lean muscle mass and size, and elevates IGF-1 levels, enhancing muscle growth and strength.
It activates satellite cells to repair damaged muscle fibers, inhibits fat production, and increases the size of motor neurons.
Testosterone primarily exerts its muscle-building effects by interacting with androgen receptors located in muscle cells.
It also stimulates erythropoietin production, increasing red blood cell count and improving oxygen-carrying capacity, thereby enhancing endurance.
Testosterone is considered the most effective bulking agent, and Testosterone Suspension, in particular, provides rapid results.
Higher doses lead to greater muscle growth, and its versatile nature as an endogenous anabolic steroid allows for use in various goals.
Testosterone Suspension
| Chemical Name | 4-Androsten-3-one-17beta-ol, 17beta-Hydroxy-androst-4-en-3-one |
| Molecular Weight | 288.42 g/mol |
| Formula | C19H28O2 |
| Manufacturer | N/A |
| Half-Life | 2-4 hours (Some reports indicate up to 39 hours) |
| Detection Time | 1-3 days |
| Anabolic Rating | 100 |
| Androgenic Rating | 100 |
Testosterone Suspension Overview and History
Testosterone Suspension is an injectable consisting of pure testosterone, almost always in a microcrystalline form, suspended in water (hence the name Testosterone Suspension).
Within the bodybuilding and athletic communities, Testosterone Suspension is regarded as the most potent and highly efficacious form of injectable testosterone.
It is known to produce the fastest mass, strength, and physical changes of any injectable testosterone formulation.
There are several reasons for this.
The first reason is that it is the purest form of testosterone, unmodified and non-esterified, meaning it is active in the body the moment it is injected.
Furthermore, because the testosterone molecule lacks an attached ester, the total testosterone content per 1mg of Testosterone Suspension is greater, making it a much more potent product.
Since the weight of the ester must be included in the total weight of the substance, esterified forms of testosterone (or any hormone), such as Testosterone Propionate, Testosterone Enanthate, and Testosterone Cypionate, do not yield 100mg of testosterone from 100mg of the compound; for example, 100mg of Testosterone Enanthate does not produce 100mg of testosterone.
When the ester attached to the molecule is cleaved off in the body, the weight of the ester is removed, so, for instance, 100mg of Testosterone Enanthate actually contains only about 70mg of testosterone.
However, 100mg of Testosterone Suspension yields exactly 100mg of testosterone.
Esterified testosterone variants often take several weeks after use to reach optimal peak blood levels due to their long half-lives and the necessity for the ester to be cleaved (before pure testosterone is released).
In contrast, Testosterone Suspension often reaches optimal peak blood levels within hours.
For example, with long-acting testosterone esters like Testosterone Enanthate and Cypionate, increases in muscle mass and strength typically appear around 4-5 weeks (up to 6 weeks for some users) later.
However, effects from Testosterone Suspension commonly appear within the first week of use, and by the time a Testosterone Suspension cycle reaches 4 weeks, most of the gains have been achieved (whereas with long-acting testosterones, gains are just beginning to manifest over the same period).
Testosterone Suspension is the oldest anabolic steroid formulation, first isolated and synthesized by German scientists in the early 1930s.
Testosterone Suspension was the first testosterone formulation developed, predating esterified testosterones by several years.
Although Testosterone Propionate was developed in the mid-1930s and Testosterone Enanthate was released in the 1950s, Testosterone Suspension remained very popular during this period despite being widely perceived as a crude and inconvenient form of testosterone due to injection pain and its very short half-life requiring frequent injections.
In comparison, Testosterone Propionate required injection every other day or every 4 days, and Testosterone Enanthate required injection once or twice a week.
Testosterone Suspension required a minimum of daily, sometimes even multiple times per day, injections.
Testosterone Suspension is the longest-running testosterone product on the US and international prescription markets, having been sold in the US under various trade and brand names (e.g., Sterotate by Ulmer, Andronaq by Central, Aqua Suspension Testosterone by Pitman-Moore, Injectable Aqueous Testosterone by Arlongton-Funk, Virosterone by Endo, Testosterone Aqueous by National Drug Company, etc.).
Testosterone Suspension is the most widely used and manufactured in numerous quantities and brands, available both as generics and under brand names.
Of course, the clinical and medical applications of Testosterone Suspension are identical to all other testosterone products.
These have included the treatment of low libido (lack of sex drive), male impotence, hypogonadism and male menopause (inadequate testosterone production in males), delayed puberty in adolescent males, and even female breast cancer, among several other conditions.
From the late 1980s through the 1990s, the FDA revised and reduced the list of approved therapies for it, as with all other anabolic steroids.
Subsequently, Testosterone Suspension was determined to be a drug focused almost exclusively on the treatment of hypogonadism and male menopause, though it remains available today as a last resort for the treatment of breast cancer in women (a very rare occurrence considering the high incidence of virilization with testosterone in females).
In fact, Testosterone Suspension was used quite widely in the US prescription market until 1998.
In 1998, Testosterone Suspension was primarily manufactured in the US by Steris Laboratories, which was one of the last companies manufacturing the drug for medical use.
At that time, the FDA forced Steris to halt production of all Schedule III drugs (including Testosterone Suspension) due to minor issues related to the compounding of Schedule III drugs involving inventory report discrepancies.
A few years later, Steris had the opportunity to resume production of Testosterone Suspension but decided against it.
As a result, pharmaceutical-grade Testosterone Suspension is now only available in the US prescription drug market through private compounding pharmacies, having become a special order item that is difficult to find.
It is also still widely used in veterinary medicine.
Globally, Testosterone Suspension is highly varied and widely available, so the available dosages and concentrations differ greatly, with some products containing 100mg/ml or 50mg/ml (very common).
Testosterone Suspension is supplied in 1ml ampules or 10ml multi-use vials.
Chemical Properties of Testosterone Suspension
Testosterone Suspension is an injectable testosterone product consisting of pure, unaltered free testosterone in a microcrystalline form suspended in water.
In this case, the testosterone molecule lacks an ester bond, which drastically reduces its half-life to 2-4 hours (some studies have reported up to 24-39 hours).[1]
Again, it is important to understand that because Testosterone Suspension contains no esterified carboxylic acid, the user receives significantly more testosterone per 1mg injected than with other forms of testosterone.
100mg of Testosterone Suspension yields 100mg of testosterone.
Conversely, 100mg of Testosterone Enanthate yields only 70mg of testosterone (the Enanthate ester is removed by the body’s enzymes, leaving free testosterone).
Properties of Testosterone Suspension
Research has shown that testosterone is known to promote significant nitrogen retention in muscle tissue, greatly increasing lean muscle mass and muscle size.[2]
Testosterone is also well-known for significantly increasing IGF-1 (Insulin-like Growth Factor 1) levels in muscle tissue, greatly enhancing muscle size and strength.[3]
Research into the action of testosterone within muscle tissue has shown that it works primarily by activating satellite cells in muscle tissue, which are crucial for repairing damaged muscle fibers.[4]
The same research indicates that testosterone also has the ability to inhibit fat production (fat storage) and increase motor neuron size.
Testosterone has been found to achieve its muscle growth and strength-enhancing effects primarily through interaction with androgen receptors located in muscle cells.[5]
Furthermore, androgens like testosterone stimulate erythropoietin production in the kidneys, increasing red blood cell count, which improves oxygen transport throughout the body and enhances an athlete’s endurance.[6]
Generally, testosterone is considered one of the top mass-building and bulking agents.
Individuals seeking to bulk up can expect faster results with Testosterone Suspension than with any other form of testosterone.
It has also been found that there is a relationship between the dose used and the amount of muscle growth, with higher doses yielding greater gains.[7]
Testosterone can be considered the original anabolic steroid, produced naturally and endogenously in all humans and most animal species.
Being the most versatile anabolic steroid, Testosterone Suspension can be utilized for any specific goal.
Testosterone Suspension References
[1] J Vet Pharmacol Ther. March 2, 2011. doi: 10.1111/j.1365-2885.2011.01277.x
[2] Testosterone replacement therapy increases lean body mass and muscle size in hypogonadal men.
Bhasin S, Storer TW, Berman N, Yarasheski KE, Clevenger B, Phillips J, Lee WP, Bunnell TJ, Casaburi R.
J Clin Endocrinol Metab. 1997 Feb;82(2):407-13.
[3] Testosterone administration improves muscle function in older men: molecular and physiological mechanisms.
Ferrando AA, Sheffield-Moore M, Yeckel CW, Gilkison C, Jiang J, Achacosa A, Lieberman SA, Tipton K, Wolfe RR, Urban RJ.
Am J Physiol Endocrinol Metab. 2002 Mar;282(3):E601-7.
[4] Testosterone action on skeletal muscle.
Herbst KL, Bhasin S.
Curr Opin Clin Nutr Metab Care. 2004 May;7(3):271-7.
[5] Strategies targeting steroid hormone receptor pathways in the treatment of hormone dependent cancers.
Ko YJ, Balk SP.
Curr Pharm Biotechnol. 2004 Oct;5(5):459-70.
[6] [Effect of androgen on erythropoietin in patients with hypogonadism].
Cui YG, Tong JS, Pan QQ, Di FS, Jia Y, Feng T, Liu Y, Wang XH, Zhang GY.
Zhonghua Nan Ke Xue. 2003;9(4):248-51.
[7] Testosterone dose-dependently increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension.
Storer TW, Magliano L, Woodhouse L, Lee ML, Dzekov C, Dzekov J, Casaburi R, Bhasin S.
J Clin Endocrinol Metab. 2003 Apr;88(4):1478-85.
