Testosterone is the primary sex hormone in humans, crucial for the development of male and female reproductive tissues. It also promotes secondary sexual characteristics such as increased muscle and bone mass, body hair growth, and overall well-being. Essential for maintaining health and preventing conditions like osteoporosis, insufficient levels in men can lead to frailty and bone loss. Testosterone has both athletic and medical applications, including treatments for gender dysphoria, male hypogonadism, and certain types of breast cancer.
Mechanism of Action
Testosterone binds to androgen receptors and is a precursor to dihydrotestosterone (DHT), formed through the action of the enzyme 5α-reductase. DHT has a higher affinity for androgen receptors. These hormones bind to these receptors, triggering changes in gene activity and mediating androgenic effects. Testosterone can also convert to estrogen via aromatization. Estrogens, rather than testosterone, primarily activate feedback mechanisms and suppress endogenous testosterone secretion when exogenous testosterone is administered.
Medical Use
Testosterone is on the World Health Organization’s list of essential medicines, underscoring its importance in basic healthcare. It treats gender dysphoria, male hypogonadism, and certain breast cancers. Hormone replacement therapy (HRT) or testosterone replacement therapy (TRT) helps maintain normal testosterone levels, especially as men age and experience declining production. TRT can improve well-being, sexual function, and body composition.
Testosterone for Seniors
Men over 35 with declining well-being are often advised to test their testosterone levels. If levels are below 12 nmol/l, hormone replacement therapy may be recommended. This approach can improve body composition (reduce fat, increase muscle mass), rejuvenate sexual function, and reverse negative effects associated with androgen deficiency. Regular monitoring of lipid profiles, blood parameters, estradiol, and prolactin levels is essential. For those desiring offspring, specific therapy with gonadotropins may be required.
Testosterone in Sports
Testosterone’s main advantage in sports is increasing muscle mass and strength. It has both anabolic and androgenic effects, interacting with androgen receptors to alter gene expression and protein synthesis. It can also promote water retention, joint health, regeneration, and enhanced oxygen-carrying capacity in the blood. Typical dosages in sports range from 250 to 500 mg per week, adjusted for body weight. Cycles usually last 8 to 10 weeks, followed by post-cycle therapy. Monitoring estradiol levels and using aromatase inhibitors are important to manage potential estrogenic side effects.
Dosages
- Beginner: 50 mg every other day (EOD)
- Average Dosage: 100-150 mg EOD
- High Dosage: 100 mg or more per day (ED)
Effects
- Increased muscle mass
- Development of male genital organs and secondary sexual characteristics
- Spermatogenesis and male sexual behavior
- Enhanced muscle strength
- Reduction in blood cholesterol levels
- Lower risk of heart ischemia and coronary heart disease
- Stimulation of erythropoiesis
- Influences nitrogen and phosphorus metabolism
Side Effects
- Increased blood pressure
- Heightened sexual behavior
- Increased blood clotting tendency
- Possible formation of blood clots in arteries and veins
- Water retention (edema)
- Masculinization effects
- Aggression, agitation, irritability
- Alopecia (baldness)
- Acne
- Insomnia (rare)
Profile
- Half-life: 20 hours
- Frequency of Injections: 1-2 days
Pharmaceutical Form
- Oily solution for intramuscular injection
Contraindications
- Pregnancy
- Known or suspected carcinoma of the prostate or breast
- Breastfeeding
- Hypersensitivity to the active substance or any excipients
How to Store
- Do not use after the expiry date
- Store between 8º to 30ºC
- Avoid freezing
- Protect from light









