Halos (Fluoxymesterone)

About the Product

Halos is a research compound from Driada Medical, containing Fluoxymesterone. Fluoxymesterone is a synthetic, orally active anabolic-androgenic steroid (AAS) and a 17α-alkylated derivative of testosterone . Its molecular formula is C₂₀H₂₉FO₃, with a molecular weight of 336.45 g/mol . It is a white, odorless, crystalline powder, practically insoluble in water .

The compound is characterized by distinct structural features:

• 9α-fluoro group: This modification contributes to its potent androgenic properties and resistance to metabolism .

• 17α-methyl group: Provides oral bioavailability by hindering hepatic metabolism, but is also associated with potential hepatotoxic effects .

• 11β-hydroxy group: Contributes to its overall molecular stability .

The product is intended for laboratory research use only and features an integrated QR code on the packaging for detailed product verification.

• Product Name: Halos (Fluoxymesterone)

• Brand: Driada Medical

• Form: Solution for research applications

• CAS: 76-43-7

• For Research Use Only.

Research Applications & Mechanism of Action

• Androgen Receptor Agonist with Distinct Profile: Fluoxymesterone functions as an agonist at the androgen receptor (AR) . It is characterized by a low binding affinity for the AR but functions as a potent activator of AR-mediated transcription at sufficiently high concentrations . Studies show its relative binding affinity (RBA) is <5 compared to methyltrienolone (reference compound), yet it is a potent transcriptional activator .

• Lower Potency Agonist: In functional assays, fluoxymesterone is considered a lower potency agonist compared to high-affinity ligands like DHT. It requires concentrations of 10-100 nM to induce the AR N/C (NH2-terminal and carboxyl-terminal) interaction, a process that facilitates agonist potency, by up to 23-fold .

• Androgenic Activity: Fluoxymesterone has a relatively high ratio of androgenic to anabolic activity, similar to testosterone . It promotes protein anabolism, nitrogen retention, and the development of male secondary sex characteristics .

• Oral Bioavailability: The 17α-alkylated structure enables oral administration in research models, avoiding the need for injection .

• Erythropoiesis Stimulation: Like other androgens, fluoxymesterone has been reported to stimulate the production of red blood cells by enhancing erythropoietic stimulation factor .

• Hepatotoxicity Research: Fluoxymesterone, as a 17α-alkylated AAS, is of significant interest for hepatotoxicity studies. Research demonstrates direct toxicity to hepatocytes, with a structural-activity relationship indicating that 17α-alkylated steroids show direct toxicity while non-alkylated steroids do not . Ultrastructural studies reveal that fluoxymesterone treatment induces mitochondrial swelling (with electron-lucent matrix and indistinct cristae) and a marked increase in lysosomes in hepatic cells, indicating cellular stress and potential liver damage .

• 17-Epimerization Research: Fluoxymesterone has been used to study 17-epimerization, a metabolic process where the 17α-methyl anabolic steroids undergo conversion to 17β-methyl epimers. This process is of interest in metabolism and anti-doping research .

Research & Scientific Background

• Chemical Background: Fluoxymesterone (Halotestin) is a 17α-alkylated derivative of testosterone developed by Pharmacia & Upjohn and approved by the FDA in 1956 .

• Clinical Context: Clinically, fluoxymesterone has been indicated for replacement therapy in male hypogonadism and for palliation of androgen-responsive recurrent breast cancer in women . Its clinical use has diminished over time due to its side-effect profile.

• Androgen Receptor Research: Fluoxymesterone's distinct pharmacology—low binding affinity but potent activation—makes it valuable for studying AR activation mechanisms, such as the N/C interaction . The compound's AR binding affinity has been a subject of study, with an EC50 of 0.3 nM reported in some sources .

• Hepatotoxicity & Structural-Activity Relationship: Studies in primary rat hepatic cell cultures have demonstrated that fluoxymesterone and other 17α-alkylated steroids are directly toxic to hepatocytes, whereas non-alkylated steroids show no effects at similar doses . This structural-activity relationship is crucial for research into AAS-induced liver injury. In vivo, high-dose fluoxymesterone treatment in rats induced mitochondrial swelling and lysosomal proliferation, and these ultrastructural changes were not detected by conventional liver function tests .

• Metabolism & 17-Epimerization: Fluoxymesterone undergoes metabolic transformation, including 17-epimerization, which has been characterized in excretion studies. The extent of epimerization depends on the A-ring structure .

• Pharmacokinetics: Fluoxymesterone has a relatively long elimination half-life of approximately 9.2 hours . It is known to be affected by the 17α-alkylated structure, which allows for oral bioavailability .