Absorption, Distribution and Excretion
Testosterone propionate is an esterified anabolic steroid, giving it higher solubility in fats and thus a slower rate of release and absorption compared to its homologues. Following an intramuscular injection of 200 mg testosterone propionate, the mean peak plasma concentration (Cmax) reaches 1122 ng/dL, higher than the therapeutic concentration, occurring 4–5 days post-injection. After day 5, plasma testosterone propionate concentrations decrease, averaging 400 ng/dL. Approximately 90% of intramuscularly injected testosterone is excreted in the urine as glucuronic acid and sulfate conjugates, which are testosterone and its metabolites; approximately 6% is excreted in the feces, primarily in unconjugated form. The volume of distribution after intravenous injection of testosterone is approximately 1 L/kg. The clearance of intramuscularly injected testosterone propionate is lower compared to other testosterone analogues. Metabolism/Metabolites Testosterone propionate must be processed by enzymes in the blood to exert its effects. These enzymes break the bond between the propionate ester and testosterone. After separation, testosterone is metabolized into 17-ketosteroids via two distinct pathways. The main active metabolites are estradiol and dihydrotestosterone (DHT). Testosterone is metabolized to DHT by steroid 5α-reductase in the skin, liver, and urogenital tract. In reproductive tissues, DHT is further metabolized to androstenedione.

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Biological Half-Life
Testosterone propionate has one of the longest half-lives, approximately 8 days.

Protein Binding
After testosterone propionate is converted to testosterone, approximately 98% of it binds to sex hormone-binding globulin in the blood plasma.

Testosterone propionate may cause developmental toxicity depending on state or federal labeling requirements. Testosterone propionate is a sterol ester. It is functionally related to 3-cyclopentylpropionic acid and testosterone. Testosterone propionate is a synthetic derivative of testosterone, existing as an oil-soluble 17(β)-cyclopentylpropionate ester. Its advantages over other testosterone derivatives include a slower release rate after injection and a longer half-life. It was developed by Pharmacia & Upjohn and approved by the FDA on July 25, 1979. Testosterone propionate is the octane ester form of testosterone. The number of carbon atoms in the ester is related to the half-life of the prodrug. Testosterone inhibits the pituitary gland from secreting gonadotropins and inhibits the ovaries from producing estrogen, thereby reducing endogenous estrogen levels. Furthermore, this drug helps maintain male sexual characteristics and is indicated for testosterone replacement therapy in men with hypogonadism. (NCI04)
See also: Testosterone (containing active ingredient); Estradiol cyclopentylpropionate; Testosterone cyclopentylpropionate (ingredient).

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Drug Indications
Testosterone cyclopentylpropionate is used to treat male disorders caused by endogenous testosterone deficiency or absence. These disorders include: 1) primary hypogonadism, defined as testicular failure caused by cryptorchidism, bilateral testicular torsion, orchitis, disappearance of the testis syndrome, or orchiectomy; 2) hypogonadotropic hypogonadism, characterized by idiopathic gonadotropin, LHRH deficiency, or pituitary-hypothalamic damage caused by tumors, trauma, or radiation.
FDA Label
Mechanism of Action
Testosterone exerts its effects in humans and other vertebrates primarily through two mechanisms: activation of androgen receptors (directly or in the form of DHT), and conversion to estradiol and activation of certain estrogen receptors. Free testosterone (T) is transported to the cytoplasm of target tissue cells, where it can bind to androgen receptors or be reduced to 5α-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5α-reductase. Dihydrotestosterone (DHT) binds to the same androgen receptor even more strongly than testosterone (T), thus its androgenic potency is approximately 2.5 times that of T. A structural change occurs in the T receptor or DHT receptor complex, allowing it to enter the cell nucleus and bind directly to specific nucleotide sequences in chromosomal DNA. These binding regions, called hormone response elements (HREs), influence the transcriptional activity of certain genes, thereby producing androgenic effects.
Pharmacodynamics
Following injection of testosterone ester derivatives (such as testosterone propionate), serum testosterone levels rise to 400% of baseline within 24 hours. These androgen levels continue to rise for 3–5 days after the first dose. The sustained fluctuations in plasma testosterone levels following intramuscular injection of testosterone propionate can lead to mood and libido fluctuations, as well as some local inflammation.

C27H40O3

412.61

412.297

58-20-8

441404

Typically exists as solid at room temperature

1.1±0.1 g/cm3

525.9±50.0 °C at 760 mmHg

98 - 104ºC

223.9±30.2 °C

0.0±1.4 mmHg at 25°C

1.546

6.93

0

3

5

30

732

6

C[C@@]12CCC(=O)C=C2CC[C@H]3[C@@H]4CC[C@@H]([C@@]4(C)CC[C@@H]31)OC(=O)CCC5CCCC5

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)