Testosterone enanthate
[CAS# 315-37-7]

Identification

• Classification: API >> Hormone and endocrine-regulating drugs >> Androgen and anabolic hormone drugs
• Name: Testosterone enanthate
• Synonyms: Testosterone heptanoate; 17b-Hydroxyandrost-4-en-3-one-17-ethanate
• Molecular Formula: C₂₆H₄₀O₃
• Molecular Weight: 400.60
• CAS Registry Number: 315-37-7
• EC Number: 206-253-5
• SMILES: CCCCCCC(=O)O[C@H]1CC[C@@H]2[C@@]1(CC[C@H]3[C@H]2CCC4=CC(=O)CC[C@]34C)C

Properties

• Density: 1.1±0.1 g/cm³ Calc.^*
• Melting point: 34-39 °C (Expl.)
• Boiling point: 503.9±50.0 °C 760 mmHg (Calc.)^*
• Flash point: 214.2±30.2 °C (Calc.)^*
• Index of refraction: 1.529 (Calc.)^*
• Alpha: 77 ° (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07;GHS08 Danger
• Risk Statements: H302-H312-H332-H350-H351-H360-H361
• Safety Statements: P203-P261-P264-P270-P271-P280-P301+P317-P302+P352-P304+P340-P317-P318-P321-P330-P362+P364-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Carcinogenicity	Carc.	1B	H350
Reproductive toxicity	Repr.	2	H361
Carcinogenicity	Carc.	2	H351
Reproductive toxicity	Repr.	1B	H360
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312
Reproductive toxicity	Lact.	-	H362
Reproductive toxicity	Repr.	1A	H360
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Specific target organ toxicity - repeated exposure	STOT RE	1	H372

Discovery and Applications

Testosterone enanthate is a synthetic ester of the naturally occurring androgen hormone testosterone. Chemically, it is the testosterone molecule chemically bonded to enanthic acid (heptanoic acid) via an ester linkage at the 17-beta hydroxyl group. This modification significantly prolongs the hormone's half-life and duration of action when administered, making testosterone enanthate a widely used androgen and anabolic steroid in medicine and sports.

The compound appears as a white or off-white crystalline powder and is practically insoluble in water but soluble in oils and organic solvents, which allows it to be formulated as an oil-based injectable preparation. After intramuscular injection, testosterone enanthate is slowly hydrolyzed by esterases in the body, releasing active free testosterone gradually into the bloodstream over several days to weeks.

Testosterone enanthate was first introduced in the mid-20th century as a treatment for male hypogonadism—a condition where the body produces insufficient testosterone. It has since been widely used for testosterone replacement therapy to restore normal serum testosterone levels, thereby alleviating symptoms such as decreased libido, fatigue, muscle wasting, and osteoporosis. It is also prescribed for delayed puberty in males, certain types of breast cancer in women, and other clinical conditions requiring androgen supplementation.

In medical practice, testosterone enanthate is administered via intramuscular injection, typically every one to four weeks, depending on the patient's condition and response. Its extended release profile reduces the frequency of injections compared to non-esterified testosterone. Blood testosterone levels peak within 24 to 48 hours post-injection and decline gradually over approximately two to three weeks.

The pharmacological effects of testosterone enanthate mirror those of endogenous testosterone, including promotion of male secondary sexual characteristics, increased muscle mass and strength, stimulation of erythropoiesis, and maintenance of libido and mood. It acts through androgen receptors to regulate gene expression in target tissues.

Testosterone enanthate has also been used illicitly as a performance-enhancing drug in sports due to its anabolic effects. Its use in competitive sports is banned by most sporting organizations. Abuse of testosterone enanthate can lead to adverse effects such as cardiovascular issues, hormonal imbalances, liver toxicity, and behavioral changes.

Pharmacokinetically, the esterification with enanthate prolongs the half-life of testosterone in the body to approximately 4.5 days, allowing for sustained physiological levels with less frequent dosing. The compound is metabolized primarily in the liver and excreted via the urine.

Side effects may include acne, fluid retention, gynecomastia, changes in cholesterol levels, and suppression of natural testosterone production due to feedback inhibition of the hypothalamic-pituitary-gonadal axis. Careful medical supervision is required during therapy to monitor hormone levels and mitigate risks.

In summary, testosterone enanthate is a long-acting testosterone ester extensively used in androgen replacement therapy. Its design enhances the pharmacokinetic profile of testosterone, providing sustained hormone release and improved patient compliance. Despite its medical benefits, it requires careful management due to potential side effects and regulatory controls on its use.

References

2021. Cardiovascular risk and testosterone - from subclinical atherosclerosis to lipoprotein function to heart failure. Reviews in Endocrine and Metabolic Disorders, 22(2).
DOI: 10.1007/s11154-021-09628-2

2020. How the love of muscle can break a heart: Impact of anabolic androgenic steroids on skeletal muscle hypertrophy, metabolic and cardiovascular health. Reviews in Endocrine and Metabolic Disorders, 22(2).
DOI: 10.1007/s11154-020-09616-y

2010. Testosterone replacement in male hypogonadism. Clinical pharmacology : advances and applications, 2.
DOI: 10.2147/cpaa.s11940