Description

Testosterone undecanoate is a long-acting form of the primary male sex hormone, testosterone. This hormone plays a key role in the development of male reproductive tissues, such as the testes and prostate, and also contributes to female reproductive function. It is also responsible for the development of secondary sexual characteristics, including increased muscle and bone mass and body hair growth in men.

In addition to its reproductive functions, testosterone undecanoate is essential for overall health and well-being and plays an important role in preventing osteoporosis in both sexes. Insufficient testosterone levels in men can cause various changes, including physical frailty and bone loss.

From an anabolic standpoint, testosterone undecanoate promotes muscle mass gain, stimulates protein synthesis, accelerates recovery time, and increases muscle glycogen stores. Because testosterone regulates numerous physiological processes, it is one of the most important hormones in the human body. For this reason, testosterone undecanoate-based drugs are used both in older men suffering from age-related hypogonadism and, in athletes, as the basis of anabolic steroid protocols.

Mechanism of action

Testosterone undecanoate acts by binding to androgen receptors and is the precursor to another biologically active androgen, dihydrotestosterone (DHT) , which is formed through the action of the enzyme 5α-reductase. DHT has an affinity for androgen receptors approximately five times greater than testosterone itself.

Once bound to the receptor, the hormone-receptor complex undergoes a structural change and transmits the signal to the cell nucleus, where the androgenic effects are manifested through the regulation of the expression of specific DNA genes.

Testosterone undecanoate can also be converted to estrogens under the action of the enzyme aromatase , a process known as aromatization. In this context, estrogens in particular activate the negative feedback mechanism on the hypothalamic–pituitary–testicular axis, leading to the suppression of endogenous testosterone production in the presence of exogenous hormones.

Medical use

Testosterone is included on the World Health Organization’s List of Essential Medicines , confirming its crucial role in a basic healthcare system. Therefore, considering testosterone undecanoate solely as a steroid for muscle mass gain is reductive: it is a fundamental hormonal drug .

Clinically, testosterone undecanoate is used in the treatment of male hypogonadism , gender dysphoria , and in some cases as part of the treatment of specific forms of breast cancer .

Because testosterone levels physiologically decline with age, hormone replacement therapy , also known as testosterone replacement therapy (TRT) , may be necessary to maintain a good quality of life. Testosterone undecanoate helps maintain serum hormone levels within the physiological range, offsetting the natural decline in androgen production associated with aging.

Effects on the nervous and cognitive systems

In men, testosterone undecanoate also affects several cognitive functions, including mood, spatial ability, attention, and memory. Some preliminary evidence suggests that low testosterone levels may be a risk factor for cognitive decline and, potentially, the development of Alzheimer’s disease.

In conclusion, in both sexes, testosterone undecanoate plays a central role in maintaining general health, psychophysical well-being and in the prevention of numerous pathologies.