|Trade names||Halotestin, Ora-Testryl, Ultandren, others|
|Other names||Fluoxymestrone; Androfluorene; NSC-12165; 9α-Fluoro-11β-hydroxy-17α-methyltestosterone; 9α-Fluoro-17α-methylandrost-4-en-11β,17β-diol-3-one|
|Drug class||Androgen; Anabolic steroid|
|Metabolism||Liver (6β-hydroxylation, 5α- and 5β-reduction, 3α- and 3β-keto-oxidation, 11β-hydroxy-oxidation)|
|Elimination half-life||9.2 hours|
|Excretion||Urine (<5% unchanged)|
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||336.447 g·mol−1|
|3D model (JSmol)|
Fluoxymesterone, sold under the brand names Halotestin and Ultandren among others, is an androgen and anabolic steroid (AAS) medication which is used in the treatment of low testosterone levels in men, delayed puberty in boys, breast cancer in women, and anemia. It is taken by mouth.
Side effects of fluoxymesterone include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire. It can also cause liver damage and cardiovascular side effects like high blood pressure. The drug is a synthetic androgen and anabolic steroid and hence is an agonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). It has strong androgenic effects and moderate anabolic effects, which make it useful for producing masculinization.
Fluoxymesterone was first described in 1956 and was introduced for medical use in 1957. In addition to its medical use, fluoxymesterone is used to improve physique and performance. The drug is a controlled substance in many countries and so non-medical use is generally illicit.
Fluoxymesterone is or has been used in the treatment of hypogonadism, delayed puberty, and anemia in males and the treatment of breast cancer in women. It is specifically approved in one or more countries for the treatment of hypogonadism in men, delayed puberty in boys, and breast cancer in women. Current prescribing guidelines in the United States list only the treatment of androgen deficiency in males and breast cancer in females as indications.
Fluoxymesterone is less effective in inducing masculinization than testosterone, but is useful for maintaining established masculinization in adults.
|Notes: In rodents. Footnotes: a = Ratio of androgenic to anabolic activity. Sources: See template.|
As an AAS, fluoxymesterone is an agonist of the androgen receptor (AR), similarly to androgens like testosterone and DHT. It is a substrate for 5α-reductase like testosterone, and so is potentiated in so-called “androgenic” tissues like the skin, hair follicles, and prostate gland via transformation into 5α-dihydrofluoxymesterone. As such, fluoxymesterone has a relatively poor ratio of anabolic to androgenic activity similarly to testosterone and methyltestosterone. However, fluoxymesterone is nonetheless proportionally less androgenic and more anabolic than methyltestosterone and testosterone.
Fluoxymesterone has been reported to be non-aromatizable due to steric hindrance by its C11β hydroxyl group, and hence is not considered to have a propensity for producing estrogenic effects such as gynecomastia or fluid retention. However, paradoxically, a case report of severe fluoxymesterone-induced gynecomastia exists, and gynecomastia associated with fluoxymesterone has also been reported in other publications, although this may not be due to estrogenic activity. Fluoxymesterone is thought to possess little or no progestogenic activity.
Fluoxymesterone has been found to act as a potent inhibitor of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) (IC50 = 60–630 nM), with a potency comparable to that of the 11β-HSD2 inhibitor glycyrrhetinic acid. This action of fluoxymesterone is unique among AAS and is likely related to its 11β-hydroxyl group. 11β-HSD2 is responsible for the inactivation of the glucocorticoids cortisol and corticosterone (into cortisone and 11-dehydrocorticosterone, respectively). Inhibition of 11β-HSD2 by fluoxymesterone may result in mineralocorticoid receptor overactivation and associated side effects such as hypertension and fluid retention, and has been hypothesized to be involved in the cardiovascular and other adverse effects of fluoxymesterone.
Unlike other AAS, fluoxymesterone has structural features in common with corticosteroids, including its C9α fluoro and C11β hydroxyl groups. In relation to this, it has weak (micromolar) but potentially clinically significant affinity for the glucocorticoid receptor.
Fluoxymesterone has approximately 80% oral bioavailability, unlike testosterone, as the C17α methyl group of fluoxymesterone inhibits first-pass metabolism. It has very low affinity for human serum sex hormone-binding globulin (SHBG), less than 5% of that of testosterone and less than 1% of that of DHT. The drug is metabolized in the liver, mainly by 6β-hydroxylation, 5α- and 5β-reduction, 3α- and 3β-keto-oxidation, and 11β-hydroxy-oxidation. Its known active metabolites include 5α-dihydrofluoxymesterone and 11-oxofluoxymesterone. Fluoxymesterone has an elimination half-life of approximately 9.2 hours, which is long relative to that of testosterone. It is eliminated in the urine, with less than 5% excreted unchanged.
Fluoxymesterone, also known as 9α-fluoro-11β-hydroxy-17α-methyltestosterone or as 9α-fluoro-17α-methylandrost-4-en-11β,17β-diol-3-one, is a synthetic androstane steroid and a 17α-alkylated derivative of testosterone (androst-4-en-17β-ol-3-one). It is specifically the derivative of testosterone with a fluorine atom at the C9α position, a hydroxyl group at the C11β position, and a methyl group at the C17α position.
Step one: The first step in the synthesis of fluoxymesterone is the microbiological oxidation of commercially available androstenedione (1.11) by Actinomyces; this introduces a hydroxyl group to the 11α-position (1.12), which is then oxidised to a ketone using Jones’ reagent, yielding the 3,11,17-triketone, adrenosterone (1.13). Pyrrolidine then reacts to form an enamine (1.14) by reaction with the 3α-keto group, protecting it from alkylation in a subsequent step. The regioselectivity of pyrrolidine for reaction at the 3α-position occurs inherently in the structure of adrenosterone, due to the position of the sterically bulky methyl groups. In subsequent steps, alkylation of the 17-keto group (1.14) using Grignard reagent, addition of hydride at the 11-position (1.15) and regeneration of the protected 3-keto group yields the starting material (1.16) for the final steps of the fluoxymesterone synthesis. This involves more standard synthetic transformations.
Step two: The 11α-hydroxyl of the starting material (1.16) is sulfonylated by p-toluenesulfonyl chloride; addition of trimethylamine (base) deprotonates the 11α-carbon, yielding an (E2) elimination of tosylate (pka – 5) to give olefin (1.17). Stereospecificity of reaction between olefin and hypobromous acid (HOBr) in base, N-bromosuccinimide (NBS), is determined by the formation of a bromonium intermediate; the electrophilic bromonium cation approaches the ring’s less sterically hindered α-face and is attacked by the π-electron density of the alkene. The hydroxide ion then attacks from above the ring (β-face) at the 11-carbon, resulting in a structure (1.18) by the stereospecific addition of hydroxyl and bromine across the double bond. Addition of sodium hydroxide results in deprotonation of the 11α-hydroxyl, and the subsequent structure undergoes an intramolecular SN2 epoxy ring formation. The epoxy ring of the β-epoxide (1.19) is protonated to give an oxironium ion intermediate. In a concerted process, fluoride attacks the ring’s α-face from below, as one of the two oxygen-carbon bonds is broken on the opposite face; hence regenerating the 11α-hydroxyl trans to the fluorine substituent. The resulting structure (1.20) is the androgenic steroid, fluoxymesterone.
Detection in body fluids
Detection of halotestin and other such illegal anabolic steroids in sports is achieved by GS-MS identification of urinary excreted anabolic steroids and their metabolites. In a test for halotestin, a dry residue obtained from a urine sample is dissolved in dimethylformamide and a sulfur trioxide-pyridine complex and is heated with 1% potassium carbonate solution. Halotestin and many of its metabolites contain two polar hydroxyl groups, leading to intermolecular hydrogen bonding that increases their boiling point and reduces volatility. In order to attain a gaseous sample for GC-MS, the products of hydrolysis are extracted, dissolved in methanol and derivatised to form volatile trimethylsilyl (TMS) esters by adding N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) and trimethylsilylimidazole (TMSImi).
Fluoxymesterone was first described in 1956 and was introduced for medical use in the United States in 1957. Over time the use of fluoxymesterone has become increasingly controversial and limited.
Society and culture
Fluoxymesterone is one of the few AAS that remains available for medical use in the United States. The others (as of November 2017) are testosterone, testosterone cypionate, testosterone enanthate, testosterone undecanoate, methyltestosterone, oxandrolone, and oxymetholone.
What is Halotestin and how is it used?
Halotestin is a prescription medicine used to treat the symptoms of Hyopgonadism in Males and Metastatic Breast Cancer in Females. Halotestin may be used alone or with other medications.
Halotestin belongs to a class of drugs called Anabolic Steroids.
What are possible side effects of Halotestin?
Side effects of Halotestin include:
- mood changes,
- trouble sleeping,
- decreased exercise ability,
- swelling of the hands, ankles, or feet,
- unusual tiredness,
- yellowing of the eyes or skin (jaundice),
- dark urine,
- swelling of the face, tongue, or throat,
- severe dizziness, and
- trouble breathing
Specifically, in men:
- trouble urinating,
- breast swelling or tenderness,
- too frequent or prolonged erections, and
- an erection that is painful or last 4 or more hours
Specifically, in women:
- deepening of the voice,
- unusual facial or body hair growth,
- enlarged clitoris, and
- irregular menstrual periods
Get medical help right away, if you have any of the symptoms listed above.
The most common side effects of Halotestin include:
- skin color changes,
- increased or decreased sexual interest,
- oily skin,
- hair loss, and
Tell the doctor if you have any side effect that bothers you or that does not go away.
These are not all the possible side effects of Halotestin. For more information, ask your doctor or pharmacist.
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
HALOTESTIN Tablets contain fluoxymesterone, an androgenic hormone.
Fluoxymesterone is a white or nearly white, odorless, crystalline powder, melting at or about 240° C, with some decomposition. It is practically insoluble in water, sparingly soluble in alcohol, and slightly soluble in chloroform.
The chemical name for fluoxymesterone is androst-4-en-3-one, 9-fluoro-11,17- dihydroxy-17-methyl-, (11β,17β)-. The molecular formula is C20H29FO3 and the molecular weight 336.45.
The structural formula is represented below:
Each HALOTESTIN (fluoxymesterone) tablet, for oral administration, contains 2 mg, 5 mg or 10 mg fluoxymesterone. Inactive ingredients: calcium stearate, corn starch, FD&C Yellow No. 5, lactose, sorbic acid, sucrose, tragacanth. In addition, the 2 mg tablet contains FD&C Yellow No. 6 and the 5 mg and 10 mg contain FD&C Blue No. 2.
DOSAGE AND ADMINISTRATION
The dosage will vary depending upon the individual, the condition being treated, and its severity. The total daily oral dose may be administered singly or in divided (three or four) doses.
Male hypogonadism: For complete replacement in the hypogonadal male, a daily dose of 5 to 20 mg will suffice in the majority of patients. It is usually preferable to begin treatment with full therapeutic doses which are later adjusted to individual requirements. Priapism is indicative of excessive dosage and is indication for temporary withdrawal of the drug.
Delayed puberty: Dosage should be carefully titrated utilizing a low dose, appropriate skeletal monitoring, and by limiting the duration of therapy to four to six months.
Inoperable carcinoma of the breast in the female: The recommended total daily dose for palliative therapy in advanced inoperable carcinoma of the breast is 10 to 40 mg. Because of its short action, fluoxymesterone should be administered to patients in divided, rather than single, daily doses to ensure more stable blood levels. In general, it appears necessary to continue therapy for at least one month for a satisfactory subjective response, and for two to three months for an objective response.
HALOTESTIN (fluoxymesterone) Tablets, round and scored, are available in the following strengths and colors:
2 mg (peach)
Bottles of 100 NDC 0009-0014-01
5 mg (light green)
Bottles of 100 NDC 0009-0019-06
10 mg (green)
Bottles of 30 NDC 0009-0036-03
Bottles of 100 NDC 0009-0036-04
Store at controlled room temperature 20° to 25°C (68° to 77°F) [see USP].
Endocrine and urogenital
Female: the most common side effects of androgen therapy are amenorrhea and other menstrual irregularities; inhibition of gonadotropin secretion; and virilization, including deepening of the voice and clitoral enlargement. The latter usually is not reversible after androgens are discontinued. When administered to a pregnant woman, androgens can cause virilization of external genitalia of the female fetus.
Skin and appendages
Fluid and electrolyte disturbances
Suppression of clotting factors II, V, VII, and X, bleeding in patients on concomitant anticoagulant therapy, and polycythemia.
Hypersensitivity, including skin manifestations and anaphylactoid reactions.
Drug Abuse And Dependence
Controlled Substance Class: Fluoxymesterone is a controlled substance under the Anabolic Steroids Control Act, and HALOTESTIN (fluoxymesterone) Tablets has been assigned to Schedule III.
Androgens may increase sensitivity to oral anticoagulants. Dosage of the anticoagulant may require reduction in order to maintain satisfactory therapeutic hypoprothrombinemia.
Concurrent administration of oxyphenbutazone and androgens may result in elevated serum levels of oxyphenbutazone.
In diabetic patients, the metabolic effects of androgens may decrease blood glucose and, therefore, insulin requirements.
Drug/Laboratory test interferences
Androgens may decrease levels of thyroxine-binding globulin, resulting in decreased total T4 serum levels and increased resin uptake of T3 and T4. Free thyroid hormone levels remain unchanged, however, and there is no clinical evidence of thyroid dysfunction.
Prolonged use of high doses of androgens (principally the 17-α alkyl-androgens) has been associated with development of hepatic adenomas, hepatocellular carcinoma, and peliosis hepatis—all potentially life-threatening complications.
Androgen therapy should be used cautiously in males with delayed puberty. Androgens can accelerate bone maturation without producing compensatory gain in linear growth. The effect on bone maturation should be monitored by assessing bone age of the wrist and hand every six months.
This drug has not been shown to be safe and effective for the enhancement of athletic performance. Because of the potential risk of serious adverse health effects, this drug should not be used for such purpose.