Sustanon Mechanism of Action

Pharmacotherapeutic group: Androgens. ATC code: G03B A03.
Pharmacology: Pharmacodynamics: Treatment of hypogonadal men with Sustanon results in a clinically significant rise of plasma concentrations of testosterone, dihydrotestosterone, estradiol and androstenedione, as well as a decrease of SHBG (sex hormone binding globulin). Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are restored to the normal range. In hypogonadal men, treatment with Sustanon results in an improvement of testosterone deficiency symptoms. Moreover, treatment increases bone mineral density and lean body mass, and decreases body fat mass. Treatment also improves sexual function, including libido and erectile function. Treatment decreases serum LDL-C, HDL-C and triglycerides, increases hemoglobin and hematocrit, which may lead to polycythaemia. No clinically relevant changes in liver enzymes and PSA have been reported. Testosterone also produces systemic effects, such as increasing the retention of sodium, potassium and chloride leading to an increase in water retention. Treatment may result in an increase in prostate size and worsening of lower urinary tract symptoms, but no adverse effects on prostate symptoms have been observed. In hypogonadal diabetic patients, improvement of insulin sensitivity and/or reduction in blood glucose have been reported with the use of androgens. In boys with constitutional delay of growth and puberty, treatment with Sustanon accelerates growth and induces development of secondary sex characteristics. In female-to-male transsexuals, treatment with Sustanon induces masculinization.
Pharmacokinetics: Sustanon contains four esters of testosterone with different durations of action. The esters are hydrolyzed into the natural hormone testosterone as soon as they enter the general circulation.
Absorption: A single dose of Sustanon leads to an increase of total plasma testosterone with peak levels of approximately 70 nmol/l (C_max), which are reached approximately 24-48 h (t_max) after administration. Plasma testosterone levels return to the lower limit of the normal range in males in approximately 21 days.
In female-to-male transsexuals, a single dose of Sustanon repeated every two weeks resulted in mean trough testosterone levels towards the upper end of the normal male range at 2, 4 and 12 months.
Distribution: Testosterone displays a high (over 97%) non-specific binding to plasma proteins and sex hormone binding globulin in in vitro tests.
Biotransformation: Testosterone is metabolized to dihydrotestosterone and estradiol, which are further metabolized via the normal pathways.
Elimination: Excretion mainly takes place via the urine as conjugates of etiocholanolone and androsterone.
Toxicology: Preclinical safety data: Preclinical data with androgens in general reveal no hazard for humans. The use of androgens in different species has been demonstrated to result in virilisation of the external genitals of female foetuses.