Testosterone Undecanoate CAS:5949-44-0

Testosterone undecanoate (TU) provides testosterone (T) replacement for hypogonadal men when administered orally but requires multiple doses per day and produces widely variable serum T levels. We investigated the pharmacokinetics of a newly available TU preparation administered by intramuscular injection to hypogonadal men. Eight patients with Klinefelter's syndrome received either 500 mg or 1,000 mg of TU by intramuscular injection; 3 months later, the other dose was given to each man (except to one, who did not receive the 1,000-mg dose). Serum levels of reproductive hormones were measured at regular intervals before and after the injections. Mean serum T levels increased significantly at the end of the first week, from less than 10 nmol/L to 47.8+/-10.1 and 54.2+/-4.8 nmol/ L for the lower and higher doses, respectively.

Thereafter, serum T levels decreased progressively and reached the lower-normal limit for adult men by day 50 to 60. Pharmacokinetic analysis showed a terminal elimination half-life of 18.3+/-2.3 and 23.7+/-2.7 days and showed a mean residence time of 21.7+/-1.1 and 23.0+/-0.8 days for the lower and higher doses, respectively. The area under the serum T concentration-time curve and the T-distribution value related to serum T concentration were significantly higher following the 1,000-mg dose than following the 500-mg dose. The 500-mg dose, when given as the second injection, yielded optimal pharmacokinetics (defined as mean peak T values not exceeding the normal range and persistence of normal levels for at least 7 weeks), suggesting that repeated injections of 500 mg at 6-8-week intervals may provide optimal T replacement. The mean serum levels of estradiol were normalized following the injections, and prolactin levels were normal throughout the study. Significant decrease of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels was observed, with the decrease in LH levels being more pronounced. There were no significant differences in serum LH and FSH levels between the two doses. Sex hormone-binding globulin (SHBG) levels before any T therapy were near the upper limit of normal for adult men and were reduced by approximately 50% just prior to the second dose of TU.

The decreased SHBG levels produced by the first TU injection could have led to lower peak total T levels and to a more rapid clearance of T following the second TU injection. We conclude that single-dose injections of TU to hypogonadal men can maintain serum T concentration within the normal range for at least 7 weeks without immediately apparent side effects. It is likely that this form of T would require injections only at 6-8-week or longer intervals, not at the 2-week intervals necessary with currently used T esters (enanthate and cypionate). This injectable TU preparation may provide improved substitution therapy for male hypogonadism and, in addition, may be developed as an androgen component of male contraceptives.

 

 

 

Testosterone undecanoate is indicated for testosterone replacement therapy in adult males for conditions associated with a deficiency or absence of endogenous testosterone. These conditions include:

Congenital or acquired primary hypogonadism: testicular failure due to cryptorchidism, bilateral torsion, orchitis, vanishing testis syndrome, orchiectomy, Klinefelter's syndrome, chemotherapy, or toxic damage from alcohol or heavy metals. These men usually have low serum testosterone concentrations and gonadotropins (follicle-stimulating hormone FSH, luteinizing hormone LH) above the normal range.

Congenital or acquired hypogonadotropic hypogonadism: gonadotropin or luteinizing hormone-releasing hormone (LHRH) deficiency or pituitary-hypothalamic injury from tumors, trauma, or radiation. These men have low testosterone serum concentrations but have gonadotropins in the normal or low range.

Testosterone undecanoate is not used to treat age-related hypogonadism.

 

 

Testosterone is a critical male sex hormone that is responsible for the normal growth and development of the male sex organs and the maintenance of secondary sex characteristics, such as the growth and maturation of male sex organs, the development of male hair distribution, vocal cord thickening, and alterations in body musculature and fat distribution. Male hypogonadism, resulting from insufficient testosterone secretion, has two main etiologies: primary hypogonadism is caused by defects in the gonads, whereas secondary hypogonadism is the failure of the hypothalamus (or pituitary) to produce sufficient gonadotropins (FSH and LH).

In the circulation, testosterone undecanoate is cleaved by endogenous non-specific esterases to release testosterone, the active component of the compound. The undecanoate side chain is pharmacologically inactive. Testosterone can be further converted by 5α reductase to its more biologically active form, dihydrotestosterone (DHT). The actions of testosterone and DHT are mediated via androgen receptor, which is widely expressed in many tissues, including the bone, muscle, prostate, and adipose tissue. Testosterone binds to androgen receptors with high affinity and regulates target gene transcription involved in the normal growth and development of the male sex organs and the maintenance of secondary sex characteristics.Testosterone can cause improved sexual function, increased lean body mass, bone density, erythropoiesis, prostate size, and changes in lipid profiles.

 

 

Trade names	TU; Testosterone undecylate; Testosterone 17β-undecanoate; ORG-538; CLR-610
CAS	5949-44-0
Molar mass	456.711
MF	C30H48O3
Purity	Above 98%
Apprarance	Light yellow oil

 

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Testosterone undecanoate is a long-acting ester of testosterone that is used for hormone replacement therapy in men with low testosterone levels. While testosterone undecanoate can contribute to muscle growth and potentially enhance athletic performance, its effects are primarily seen in individuals with low testosterone levels rather than healthy individuals.

Here's how testosterone undecanoate can influence muscle growth:

Restoring Testosterone Levels: Testosterone is a key hormone that plays a significant role in promoting muscle protein synthesis and overall muscle growth. In individuals with low testosterone levels, hormone replacement therapy with testosterone undecanoate can restore testosterone to a more normal range, which may support muscle growth.

Enhanced Protein Synthesis: Testosterone is an anabolic hormone that helps stimulate protein synthesis in muscles. Adequate testosterone levels can contribute to increased protein synthesis, leading to muscle tissue repair and growth.

Strength and Performance: Testosterone undecanoate, by raising testosterone levels, might lead to improvements in strength, endurance, and athletic performance. These improvements could indirectly contribute to muscle growth as well.

Body Composition: Adequate testosterone levels can also influence fat distribution and body composition. Lowering body fat percentage can help reveal and enhance muscle definition.

It's important to note that the effects of testosterone undecanoate on muscle growth are context-dependent:

Individual Response: The response to testosterone therapy can vary widely from person to person. Factors like genetics, diet, exercise routine, and overall health play a role in determining how much muscle growth and performance enhancement might occur.

Health Status: Testosterone undecanoate is prescribed for individuals with low testosterone levels due to medical conditions. It is not typically prescribed for healthy individuals seeking muscle gains, and self-administration for such purposes is discouraged due to potential risks and side effects.

Supervised Use: If you have low testosterone levels and are considering testosterone replacement therapy, it's important to work closely with a qualified medical professional. They can monitor your progress, adjust dosages if necessary, and ensure that any potential risks or side effects are minimized.

In summary, while testosterone undecanoate can contribute to muscle growth and performance enhancement in individuals with low testosterone levels, it is not recommended for use by healthy individuals solely seeking to build muscle. Always prioritize your health and safety by seeking professional medical advice before considering any form of hormone therapy or performance-enhancing substances.

 

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