Complete technical data sheets for each compound: mechanism of action, pharmacokinetics, route of administration, half-life and pharmacopoeia specifications.
Testosterone propionate is a short-acting ester of testosterone, the primary male sex hormone. It is esterified with propionic acid at the 17-beta position of the steroid ring, conferring rapid release following intramuscular injection.
It acts by binding to the intracellular androgen receptor (AR), forming a hormone-receptor complex that translocates to the cell nucleus and modulates gene transcription. It promotes protein synthesis, nitrogen retention, erythropoiesis and the maintenance of male secondary sexual characteristics. Metabolically, it favors positive nitrogen balance and bone mineralization.
| Parameter | Specification |
|---|---|
| Molecular formula | C22H32O3 |
| Molecular weight | 344.49 g/mol |
| Melting point | 118 – 122 °C |
| Optical rotation [α]D | +84° a +90° (dioxano) |
| Solubility | Insoluble in water; soluble in oils, ethanol, chloroform |
| Assay (HPLC) | 97.0 – 103.0% of the declared amount |
| Total impurities | ≤ 1.0% |
| Sterility | Compliant (Ph.Eur. 2.6.1) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | Ph.Eur., USP, BP |
| Storage | 15 – 25 °C, protect from light |
Testosterone cypionate is a long-acting ester of testosterone, esterified with cyclopentylpropionic acid. After intramuscular injection, it is deposited in the muscle tissue as an oily reservoir, gradually released by enzymatic hydrolysis of tissue esterases.
Its mechanism of action is identical to that of endogenous testosterone: it binds to the nuclear androgen receptor, activating the transcription of genes responsible for protein anabolism, erythropoiesis, spermatogenesis and the maintenance of bone mineral density. It has androgenic and anabolic activity in a 1:1 ratio.
| Parameter | Specification |
|---|---|
| Molecular formula | C27H40O3 |
| Molecular weight | 412.61 g/mol |
| Melting point | 98 – 104 °C |
| Optical rotation [α]D | +85° a +92° |
| Solubility | Insoluble in water; soluble in vegetable oils, ethanol |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.0% |
| Sterility | Compliant (USP <71>) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | USP, BP |
| Storage | 20 – 25 °C, protect from light |
Testosterone enanthate is an ester of testosterone with heptanoic (enanthic) acid at the 17β position. It is the most prescribed testosterone ester worldwide for male hormone replacement therapy (HRT) due to its predictable and stable pharmacokinetic profile.
After hydrolysis of the ester in muscle tissue, free testosterone binds to the androgen receptor, exerting anabolic effects (protein synthesis, nitrogen retention, IGF-1 stimulation) and androgenic effects (development and maintenance of secondary sexual characteristics, libido, spermatogenesis). It stimulates renal erythropoiesis by increasing erythropoietin production and through direct action on bone marrow progenitors.
| Parameter | Specification |
|---|---|
| Molecular formula | C26H40O3 |
| Molecular weight | 400.60 g/mol |
| Melting point | 34 – 39 °C |
| Optical rotation [α]D | +77° a +82° |
| Appearance | White to off-white crystalline powder |
| Solubility | Insoluble in water; soluble in oils, ethanol, ether |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.0% |
| Sterility | Compliant (Ph.Eur. 2.6.1 / USP <71>) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | Ph.Eur., USP, BP, JP |
| Storage | 15 – 25 °C, protect from light |
| Ester | Concentration | CAS | Half-life | Function in the blend |
|---|---|---|---|---|
| Testosterona Propionato | 30 mg | 57-85-2 | 0.8 – 1 day | Rapid onset of action; peak at 24h |
| Testosterona Fenilpropionato | 60 mg | 1255-49-8 | 1.5 – 2 days | Early intermediate-action bridge |
| Testosterona Isocaproato | 60 mg | 15262-86-9 | 4 – 5 days | Mid-phase level maintenance |
| Testosterona Decanoato | 100 mg | 5721-91-5 | 7 – 15 days | Prolonged action; sustains baseline levels |
The blend of four testosterone esters was designed to provide staggered release of the active ingredient. Each ester has a different chain length, which determines its hydrolysis rate and, therefore, the release kinetics of free testosterone.
The propionate provides a rapid peak (24-48h), the phenylpropionate extends the action during the first few days, the isocaproate maintains levels in the intermediate phase, and the decanoate ensures sustained release for 2-3 weeks. The result is a more stable pharmacokinetic profile with fewer peak-trough fluctuations than a single ester.
| Parameter | Specification |
|---|---|
| Total testosterone base content | 176 mg equivalent per mL |
| Individual assay (HPLC) | 90.0 – 110.0% of each declared ester |
| Total impurities | ≤ 1.5% |
| Sterility | Compliant (Ph.Eur. 2.6.1) |
| Bacterial endotoxins | < 10 UE/mL |
| pH (reconstituted) | Not applicable (oil solution) |
| Pharmacopoeia de referencia | Ph.Eur., BP |
| Storage | 15 – 25 °C, protect from light |
Nandrolone decanoate is an anabolic steroid derived from 19-nortestosterone (lacking the methyl group at C-19). This structural change confers an anabolic:androgenic ratio of approximately 10:1, meaning a potent anabolic effect with reduced androgenic activity.
It binds to the androgen receptor but, unlike testosterone, is reduced by 5α-reductase to dihydronandrolone (DHN), a metabolite with lower AR affinity than DHT. This explains its lower incidence of androgenic effects such as acne, alopecia and prostatic growth. It stimulates collagen synthesis, bone calcium retention and erythropoietin production.
| Parameter | Specification |
|---|---|
| Molecular formula | C28H44O3 |
| Molecular weight | 428.65 g/mol |
| Melting point | 31 – 36 °C |
| Appearance | White to yellowish crystalline powder |
| Solubility | Insoluble in water; soluble in ethanol, oils |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.0% |
| Sterility | Compliant (Ph.Eur. 2.6.1) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | Ph.Eur., USP, BP |
| Storage | 15 – 25 °C, protect from light |
Drostanolone is an anabolic steroid derived from dihydrotestosterone (DHT) with the addition of a 2α-methyl group. This structural modification prevents its metabolism by 3-hydroxysteroid dehydrogenase in muscle tissue, granting it significant anabolic activity that DHT does not possess.
As a DHT derivative, it does not aromatize to estrogens. It possesses moderate anti-estrogenic activity by competing with the aromatase enzyme. Its anabolic:androgenic ratio is 62:25 (reference testosterone = 100:100). It promotes nitrogen retention, protein synthesis and lipolysis without significant water retention.
| Parameter | Specification |
|---|---|
| Molecular formula | C23H36O3 |
| Molecular weight | 360.53 g/mol |
| Melting point | 123 – 130 °C |
| Appearance | White crystalline powder |
| Solubility | Insoluble in water; soluble in ethanol, oils |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.5% |
| Sterility | Compliant (Ph.Eur.) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | BP (discontinued monograph in USP) |
| Storage | 15 – 25 °C, protect from light |
Methenolone enanthate is an anabolic steroid derived from dihydrotestosterone (DHT) with an additional double bond at the 1-2 position and a 1-methyl group. It is the enanthic ester of methenolone, conferring prolonged release after intramuscular injection.
It has an anabolic:androgenic ratio of 88:44 (ref. testosterone = 100:100). It does not aromatize to estrogens and has very low androgenic activity, making it one of the best-tolerated steroids. It promotes nitrogen retention, protein synthesis and has an immunostimulant effect. Indicated for catabolic states, sarcopenia, cachexia, osteoporosis and as an adjuvant in postoperative recovery.
| Parameter | Specification |
|---|---|
| Molecular formula | C27H42O3 |
| Molecular weight | 414.63 g/mol |
| Melting point | 67 – 71 °C |
| Appearance | White to slightly yellowish crystalline powder |
| Solubility | Insoluble in water; soluble in ethanol, oils, cloroformo |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.0% |
| Sterility | Compliant (Ph.Eur. 2.6.1) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | Ph.Eur., DAB (Pharmacopoeia Alemana) |
| Storage | 15 – 25 °C, protect from light |
Trenbolone acetate is an anabolic steroid derived from 19-nortestosterone with conjugated double bonds at positions 9,11 and 11,12 (triene system). These modifications confer an androgen receptor affinity 3 to 5 times greater than testosterone and an anabolic:androgenic ratio of 500:500 (ref. testosterone = 100:100).
It does not aromatize to estrogens despite being a 19-nor derivative. It binds strongly to the AR and also interacts with the glucocorticoid receptor as an antagonist, reducing the catabolic effects of cortisol. It potently stimulates protein synthesis, nitrogen retention, hepatic and muscular IGF-1 production, and increases nutrient utilization efficiency.
| Parameter | Specification |
|---|---|
| Molecular formula | C20H24O3 |
| Molecular weight | 312.41 g/mol |
| Melting point | 94 – 97 °C |
| Characteristic color | Pale yellow crystalline powder (triene chromophore) |
| Solubility | Insoluble in water; soluble in oils, ethanol, chloroform |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.5% |
| Sterility | Compliant (internal GMP specification) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | BP Vet, BioNordet internal monograph |
| Storage | 15 – 25 °C, protect from light (fotosensible) |
Stanozolol is an anabolic steroid derived from DHT with a unique structural modification: the fusion of a pyrazole ring to the A-ring of the steroid skeleton, forming a stanozolol system (pyrazole[3,4:1,2]-androstan-17β-ol). Additionally, it has a 17α-methyl group that allows it to resist hepatic first-pass metabolism.
Anabolic:androgenic ratio of 320:30 (ref. testosterone = 100:100), one of the most favorable therapeutic indices among anabolic steroids. It reduces SHBG (sex hormone-binding globulin), increasing the free fraction of circulating testosterone. It does not aromatize to estrogens. It stimulates collagen synthesis and has fibrinolytic activity, making it useful in the treatment of hereditary angioedema and lipodystrophies.
| Parameter | Specification |
|---|---|
| Molecular formula | C21H32N2O |
| Molecular weight | 328.49 g/mol |
| Melting point | 229 – 242 °C (descomposición) |
| Appearance | White crystalline powder, odorless |
| Solubility | Practically insoluble in water; slightly soluble in ethanol |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.5% |
| Particle size (susp.) | 90% < 10 μm |
| Sterility | Compliant (Ph.Eur.) |
| Pharmacopoeia de referencia | Ph.Eur., USP, BP |
| Storage | 15 – 25 °C, protect from light |
Methandrostenolone (methandienone, Dianabol®) is an anabolic steroid derived from testosterone with two key modifications: a 17α-methyl group to resist hepatic metabolism and a double bond at the 1,2 position that reduces its relative androgenicity.
Anabolic:androgenic ratio of 90-210:40-60 (ref. testosterone = 100:100). It binds to the androgen receptor and potently promotes protein synthesis, muscle glycogenesis and the retention of nitrogen, calcium, sodium, potassium and water. It moderately aromatizes to 17α-methylestradiol, an estrogen with greater activity than estradiol. The injectable version partially bypasses hepatic first pass, reducing hepatotoxicity but without completely eliminating it due to the presence of the 17α-methyl group.
| Parameter | Specification |
|---|---|
| Molecular formula | C20H28O2 |
| Molecular weight | 300.44 g/mol |
| Melting point | 163 – 167 °C |
| Appearance | White to off-white crystalline powder |
| Solubility | Slightly soluble in water; soluble in ethanol, chloroform |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.5% |
| Sterility | Compliant (Ph.Eur.) |
| Pharmacopoeia de referencia | Ph.Eur., BP |
| Storage | 15 – 25 °C, protect from light |
Oxymetholone is an anabolic steroid derived from DHT with modifications at the 17α position (methyl group) and 2-position (hydroxymethylene group). Despite being a DHT derivative, it exhibits paradoxical estrogenic activity by directly activating the estrogen receptor without enzymatic aromatization.
Anabolic:androgenic ratio of 320:45 (ref. testosterone = 100:100). It is one of the most potent oral anabolic steroids in terms of mass and strength gains. It intensely stimulates erythropoiesis (FDA-approved for aplastic, myelofibrotic and hemolytic anemias). It increases renal erythropoietin production and acts directly on erythroid precursors in bone marrow. The injectable version improves bioavailability and partially reduces hepatic burden.
| Parameter | Specification |
|---|---|
| Molecular formula | C21H32O3 |
| Molecular weight | 332.48 g/mol |
| Melting point | 172 – 180 °C |
| Appearance | White to off-white crystalline powder |
| Solubility | Practically insoluble in water; soluble in ethanol, chloroform |
| Assay (HPLC) | 97.0 – 103.0% |
| Total impurities | ≤ 1.5% |
| Sterility | Compliant (USP <71>) |
| Bacterial endotoxins | < 10 UE/mL |
| Pharmacopoeia de referencia | USP, BP |
| Storage | 15 – 25 °C, protect from light y humedad |