Thioderon — mepitiostane

Mepitiostane is a 17-beta etherified derivative of epitiostane. The ether is necessary to facilitate oral dosing, which occurs via the lymphatic system very similar to Anabolicum Vister (quirrbolone). As such, epitiostane is actually the active steroid that is provided to the user once the ether is removed metabolically, which is a non-methylated (non-hepatotoxic) derivative of dihydrotestosterone. Mepitiostane is a moderately anabolic steroid, which displays roughly the same anabolic effect as methyltestosterone on a milligram for milligram basis, at least according to standard animal assays. This activity is accompanied by only a mild androgenic component, however, which makes this steroid primarily anabolic in nature. It is also non-aromatizable, and possesses antiestrogenic properties. Although this steroid is not widely used by athletes and bodybuilders, it exhibits favorable lean muscle building properties, which tend to be accompanied by fat loss and increased definition.

Brand name Thioderon, Mepitiostane
Androgenic 25
Anabolic 100
Standard Methyltestosterone (oral)
Chemical Names 17beta-(1 -methoxycyclopentyloxy)-
Estrogenic Activity none
Progestational Activity none

Thioderon History

Mepitiostane was first described in 1966, during investigations into a series of A-ring modified androstane derivatives. The only modern pharmaceutical preparation of record containing mepitiostane is Thioderon, which is sold in Japan by Shinogi. The active drug seemed to enter extensive studies in Japan in 1974, which saw the bulk of mepitiostane research. The drug is used in Japanese medicine as an anabolic agent, and is mainly given to patients (twice daily) for the treatment of breast carcinoma and anemia associated with renal failure. In clinical trials where the agent was compared to an equal dose of fluoxymesterone (also used to treat breast carcinoma), mepitiostane was shown to offer a similar level of efficacy, but without the unwanted hepatotoxicity of a c-17alpha alkylated agent. Mepitiostane was never widely experimented with outside of Japan, and newer medicines to treat the associated conditions make it less useful today than in the past. Still, the drug remains available for sale, though it is not widely found outside of Japan.

How is Thioderon Supplied

Mepitiostane is available as a prescription drug preparation in Japan. It is supplied in the form of capsules containing 5 mg of steroid.

Structural Characteristics of Thioderon

Mepitiostane is a modified form ofdihydrotestosterone. lt differs by 1) the addition of a 17-beta methoxycyclopentyl ether, which helps facilitate lymphatic delivery (bioavailability) during oral administration, and 2) the replacement of 3-keto with 2,3alpha-epithio, which increases its anabolic strength while reducing its relative androgenicity.

Thioderon Side Effects (Estrogenic)

Mepitiostane is not aromatized by the body, and is not measurably estrogenic. Furthermore, the drug is used clinically for its inherent antiestrogenic effect. An antiestrogen is not necessary when using this steroid, as gynecomastia should not be a concern even among sensitive individuals. Since estrogen is the usual culprit with water retention, this steroid instead produces a lean, quality look to the physique with no fear of excess subcutaneous fluid retention. This makes it a favorable steroid to use during cutting cycles, when water and fat retention are major concerns.

Thioderon Side Effects (Androgenic)

Although classified as an anabolic steroid, androgenic side effects are still possible with this substance, especially with higher doses. This may include bouts of oily skin, acne, and body/facial hair growth. Anabolic/androgenic steroids may also aggravate male pattern hair loss. Women are warned of the potential virilizing effects of anabolic/androgenic steroids. These may include a deepening of the voice, menstrual irregularities, changes in skin texture, facial hair growth, and clitoral enlargement. Mepitiostane is a steroid with relatively low androgenic activity relative to its tissue-building actions, making the threshold for strong androgenic side effects comparably higher than with more androgenic agents such as testosterone, methandrostenolone, or fluoxymesterone. Note that mepitiostane is unaffected by the 5-alpha reductase enzyme, so its relative androgenicity is not affected by the concurrent use of finasteride or dutasteride.

Thioderon Side Effects (Heoatotoxicity)

Mepitiostane is not a cl 7-alpha alkylated compound, and is not known to have hepatotoxic effects. Liver toxicity is unlikely.

Thioderon Side Effects (Cardiovascular)

Anabolic/androgenic steroids can have deleterious effects on serum cholesterol. This includes a tendency to reduce HDL (good) cholesterol values and increase LDL (bad) cholesterol values, which may shift the HDL to LDL balance in a direction that favors greater risk of arteriosclerosis. The relative impact of an anabolic/androgenic steroid on serum lipids is dependant on the dose, route of administration (oral vs. injectable), type of steroid (aromatizable or non-aromatizablej/and level of resistance to hepatic metabolism. Mepitiostane should have a stronger effect on the hepatic management of cholesterol than testosterone due to its non-aromatizable nature and route of administration, but a weaker effect than c-17 alpha alkylated agents. Anabolic/androgenic steroids may also adversely effect blood pressure and triglycerides, reduce endothelial relaxation, and support left ventricular hypertrophy, all potentially increasing the risk of cardiovascular disease and myocardial infarction.

Thioderon Side Effects (Testosterone Suppression)

All anabolic/androgenic steroids when taken in doses sufficient to promote muscle gain are expected to suppress endogenous testosterone production. Without the intervention of testosterone stimulating substances, testosterone levels should return to normal within 1-4 months of drug secession. Note that prolonged hypogonadotrophic hypogonadism can develop secondary to steroid abuse, necessitating medical intervention.

Thioderon Administration (Men)

When used clinically, this drug is most commonly administered at a dose of 10 mg twice daily (20 mg total). An effective dosage of mepitiostane for physique- or performance-enhancing purposes falls in the range of 20-50 mg daily. This is usually taken for 8-12 weeks. At this level it should to impart a measurable but moderate lean-mass-building effect, which is usually accompanied by fat loss. The result is usually an increase in definition, and what is often referred to as a very "dry" look to the physique.

Thioderon Administration (Women)

When used clinically, this drug is most commonly administered at a dose of 10 mg twice daily (20 mg total). An effective dosage of mepitiostane for physique- or performance-enhancing purposes falls around 10 mg per day, taken for 4-6 weeks. Note that virilizing side effects including hoarseness, male-pattern hair growth, and acne were commonly reported in patients taking the recommended clinical dose of 20 mg per day.

Thioderon Availability

Mepitiostane is currently only produced in Japan under the Thioderon trade name. This agent is not commonly diverted for use outside of clinical settings, nor is it a known target for counterfeiting.


Wlliam Llewellyn (2017) - Anabolics

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