NEBIDO 1000 MG 4 ML AMPOULET (BAYER)

NEBIDO 1000 MG 4 ML AMPOULET (BAYER)

Testosterone undecanoate is an ester of the natural androgen testosterone. The active form, testosterone, is formed by side chain cleavage.

Testosterone is the most important androgen in men, and is synthesized mainly in the testes and, to a lesser extent, in the adrenal cortex.

Testosterone is responsible for the expression of male characteristics during fetal development, early childhood, and puberty; subsequently, the maintenance of the male phenotype and androgen-dependent functions (e.g., spermatogenesis, accessory sex glands).

Insufficient testosterone secretion results in male hypogonadism, which is characterized by low serum testosterone concentrations. Symptoms associated with male hypogonadism include decreased libido, fatigue and depressed mood, as well as absence, incomplete development or regression of secondary sexual characteristics, increased risk of osteoporosis, increased visceral fat and loss. of muscle mass and strength. Exogenous androgens are administered to improve deficient levels of endogenous testosterone and the signs and symptoms related to them.

Depending on the target organ, the spectrum of testosterone activities is mainly androgenic (e.g., prostate, seminal vesicles, epididymis) or protein anabolic (muscle, bone, hematopoiesis, kidney, liver).

The effects of testosterone on some organs arise after its peripheral conversion to estradiol, which binds to estrogen receptors in the nuclei of target cells, for example, pituitary, fat, brain, bone, and testicular Leydig cells.

In men with hypogonadism, androgens decrease body fat, increase lean body mass, muscle strength, and prevent bone loss. Androgens can improve sexual function and also exert positive psychotropic effects by improving mood.

PHARMACOKINETIC PROPERTIES:

ABSORPTION: NEBIDO® is a depot preparation of testosterone undecanoate that is administered intramuscularly and therefore avoids the first pass effect. After intramuscular injection of testosterone undecanoate in oil solution, the compound is gradually released from its depot and is almost completely metabolized by serum esterases to testosterone and undecanoic acid. The increase in serum testosterone levels above baseline values ​​can be measured one day after administration.

DISTRIBUTION: In two separate studies, mean peak concentrations of 24 and 45 nmol/L of testosterone were determined approximately 14 and 7 days, respectively, after single IM administration of 1,000 mg of testosterone undecanoate to hypogonadal males. Postmaximal testosterone levels decreased with a half-life of about 53 days.

In the serum of men, approximately 98% of circulating testosterone is bound to SHBG (Sex Hormone Bound Globulin) and albumin. Only the free fraction of testosterone is considered biologically active. To determine the apparent volume of distribution, an intravenous infusion of testosterone was performed in older adult men, presenting values ​​of approximately 1.0 L/kg.

METABOLISM: Testosterone formed by the cleavage of the testosterone undecanoate ester is metabolized and excreted in the same way as endogenous testosterone. Undecanoic acid is metabolized by ß-oxidation in the same way as other aliphatic carboxylic acids.

ELIMINATION: Testosterone is subjected to extensive hepatic and extrahepatic metabolism. After administration of radiolabeled testosterone, approximately 90% of the radioactivity appears in urine conjugated with glucuronic acid and sulfuric acid, and 6% is detected in feces after enterohepatic circulation. Urinary products include androsterone and etiocholanolone.

CONDITIONS IN EQUILIBRIUM STATE: After repeated im injection of 1,000 mg of testosterone undecanoate to hypogonadal males using a 10-week interval between two injections, steady-state conditions were achieved between the third and fifth administration. The mean Cmax and Cmin values ​​of testosterone at steady state were around 42 and 17 nmol/L, respectively. Post-maximal serum testosterone concentrations decreased with half-life of around 90 days, which corresponds to the rate of release from the depot.