Metribolone — methyltrienolone

Methyltrienolone is one of the strongest oral anabolic steroids ever produced. This agent is a derivative of trenbolone (trienolone), which has been c-17 alpha alkylated to allow for oral administration. This modification has created a steroid that is significantly stronger than its non-methylated cousin. Its potency has been measured to be anywhere from 120-300 times greater than that of methyltestosterone, with greater dissociation between anabolic and androgenic effects. Milligram for milligram methyltrienolone is a more active steroid than any agent sold on the commercial market, requiring doses as little as .5-1 milligram per day to notice a strong anabolic effect. Its potency is only matched by its relative toxicity, however, which has limited its modern use to that of laboratory research only.

Brand name Metribolone, Methyltrienolone
Androgenic 6,000-7,000
Anabolic 12,000+30,000
Standard Methyltestosterone
Chemical Names 17alpha-methyl-17beta-
Estrogenic Activity none
Progestational Activity no data available

Methyltrienolone History

Methyltrienolone was first described in 1965. It was immediately identified as an extremely potent anabolic agent, far more potent than the commercially available agents of the time. In spite of its high relative activity, however, methyltrienolone has seen very limited use in humans. It was used clinically during the late 1960’s and early ’70’s, most notably in the treatment of advanced breast cancer. Here, its exceedingly strong anabolic/androgenic action helps the drug counter the local effects of endogenous estrogens, lending it some efficacy for slowing or even regressing tumor growth. Such application was not long lived, however, as more realistic evaluations of the drug’s toxicity soon led to its abandonment in human medicine.

By the mid-1970’s, methyltrienolone was becoming an accepted standard in non-human research studies, particularly those pertaining to the study of the androgen receptor activity. For this purpose the agent is very well suited. Its sheer potency and resistance to serumbinding proteins makes it an excellent in-vitro receptor-binding standard to compare other agents to. Being so resistant to metabolism, active methyltrienolone metabolites are also not going to greatly interfere with the results of most experiments. Body tissues can metabolize most steroids fairly easily, which means that even incubation studies can be complicated with the question of what is causing a particular effect, the steroid or one of its unidentified metabolites. This is much less of an issue with methyltrienolone. Today, methyltrienolone remains an agent of research use only.

How is Methyltrienolone Supplied

Methyltrienolone is not available as a commercial agent.

Structural Characteristics of Methyltrienolone

Methyltrienolone is a modified form of nandrolone. It differs by: 1) the addition of a methyl group at carbon 17- alpha to protect the hormone during oral administration and 2) the introduction of double bonds at carbons 9 and 11, which increases its binding affinity and slows its metabolism. The resulting steroid is significantly more potent than its nandrolone base, and displays a much longer half-life and lower affinity for serum-binding proteins in comparison. Methyltrienolone chemically differs from trenbolone only by the addition of a methyl group at c-17. This alteration changes the activity of methyltrienolone considerably, however, such that this agent should not simply be considered an oral form of trenbolone.

Methyltrienolone Side Effects (Estrogenic)

Methyltrienolone is not aromatized by the body, and is not measurably estrogenic. It is of note, however, that methyltrienolone displays significant binding affinity for the progesterone receptor. The side effects associated with progesterone are similar to those of estrogen, including negative feedback inhibition of testosterone production and enhanced rate of fat storage. Progestins also augment the stimulatory effect of estrogens on mammary tissue growth. There appears to be a strong synergy between these two hormones here, such that gynecomastia might even occur with the help of progestins, without excessive estrogen levels. The use of an anti-estrogen, which inhibits the estrogenic component of this disorder, is often sufficient to mitigate gynecomastia caused by progestational anabolic/androgenic steroids.

Methyltrienolone Side Effects (Androgenic)

Although classified as an anabolic steroid, androgenic side effects are still common with this substance. 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 also 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. Additionally, the 5-alpha reductase enzyme does not metabolize methyltrienolone, so its relative androgenicity is not affected by finasteride or dutasteride.

Methyltrienolone Side Effects (Hepatotoxicity)

Methyltrienolone is a c17-alpha alkylated compound. This alteration protects the drug from deactivation by the liver, allowing a very high percentage of the drug entry into the bloodstream following oral administration. C17-alpha alkylated anabolic/androgenic steroids can be hepatotoxic. Prolonged or high exposure may result in liver damage. In rare instances life-threatening dysfunction may develop. It is advisable to visit a physician periodically during each cycle to monitor liver function and overall health. Intake of c17-alpha alkylated steroids is commonly limited to 6-8 weeks, in an effort to avoid escalating liver strain.

Methyltrienolone is an exceedingly potent oral steroid, with a very high level of resistance to hepatic metabolism. This makes methyltrienolone exceedingly liver-toxic, precluding its use as a prescription agent at this time, in any part of the world. Studies published from the University of Bonn Germany back in 1966 make this very clear. In fact, at this time researchers had deemed this the most liver-toxic steroid to ever be studied in humans, summing up their findings well when stating:

“Methyltrienolone… which is orally active as an anabolic agent in a dose less than 1.0 mg per day in normal adults,has been tested with regard to its influence on liver function. As measured by multiple parameters (BSP retention; total bilirubin; activities of transaminases, alkaline phosphates and cholinesterase in serum; activity of proaccelerin in plasma) methyltrienolone turned out to be very active as to causing biochemical symptoms of intrahepatic cholestasis. …thus methyltrienolone at present being the most ‘hepatotoxic’ steroid.”

The use of a liver detoxification supplement such as Liver Stabil, Liv-52, or Essentiale Forte is advised while taking any hepatotoxic anabolic/androgenic steroids.

Methyltrienolone 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-aromatizable), and level of resistance to hepatic metabolism. Although not extensively studied in humans, the oral route, high relative potency, and non-aromatizable nature of methyltrienolone suggest that this agent is extremely prone to negatively altering lipid values and increasing atherogenic risk. Anabolic/androgenic steroids may also adversely affect blood pressure and triglycerides, reduce endothelial relaxation, and support left ventricular hypertrophy, all potentially increasing the risk of cardiovascular disease and myocardial infarction.

To help reduce cardiovascular strain it is advised to maintain an active cardiovascular exercise program and minimize the intake of saturated fats, cholesterol, and simple carbohydrates at all times during active AAS administration. Supplementing with fish oils (4 grams per day) and a natural cholesterol/antioxidant formula such as Lipid Stabil or a product with comparable ingredients is also recommended.

Methyltrienolone 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.

Methyltrienolone Administration (General)

Studies have shown that taking an oral anabolic steroid with food may decrease its bioavailability. This is caused by the fat-soluble nature of steroid hormones, which can allow some of the drug to dissolve with undigested dietary fat, reducing its absorption from the gastrointestinal tract. For maximum utilization, methyltrienolone should be taken on an empty stomach.

Methyltrienolone Administration (Men)

Methyltrienolone is no longer used in clinical medicine due to an unacceptable level of hepatotoxicity. This agent is generally not recommended for physique- or performanceenhancing purposes for the same reason. Those absolutely insisting on its use need to take its level of liver toxicity very seriously. At the very least, routine blood tests should be conducted to ensure the agent is not imparting damage. Drug duration should also be very limited, preferably to 4 weeks of use or less. The relative potency of methyltrienolone is extremely high, requiring doses as little as .5 milligram per day. Its effective and tolerable range is usually considered to be .5 to 2mg per day. Dianabol-type doses of 20-30 mg daily are completely unthinkable, and should never be attempted. Again, this is an extremely toxic steroid, and all good advice would say to avoid it. Any one of the many commercially available steroids would be much safer choices.

Methyltrienolone Administration (Women)

Methyltrienolone is no longer used in clinical medicine due to an unacceptable level of hepatotoxicity. This agent is not recommended for women for physique- or performanceenhancing purposes due to its extremely strong toxicity and tendency to produce virilizing side effects.

Methyltrienolone Availability

Methyltrienolone is not produced as a prescription steroid product in any part of the world. With the rapid expansion of underground steroid manufacturers, this agent has been released as a black market designer compound. Those contemplating the use of underground forms of methyltrienolone should consider that such agents are being released for human use without any government approval or consideration to its safety.

Bodybuilders reference

Metribolone is the trade name for the drug Methyltrienolone, which is the most potent AAS produced. It is actually an orally active form of Trenbolone chemically altered into a 17-alkylated compound. Obviously, this means serious liver toxicity. In fact, even at microgram dosages, (1milligram = 1,000 micrograms) it is 15-20 times more toxic than Anadrol-50. That is toxic! Though orally active this AAS is provided in vials and meant for injection use only. But in truth, Metribolone is about 40-50 times more androgenic than Methyltestosterone, so a little goes a long way. The drug is fairly resistant to DHT conversion but does bind easily to scalp and prostate androgen receptor sites.

In clinical research, Metribolone is used to determine receptor-site affinity / displacement. Let me explain that. Metribolone is a very powerful androgen receptor-site stimulator and antagonist. I doubt there is any AAS more powerful. Since it binds so strongly to the receptor-site, researchers use the drug to see if other drugs can dislocate it, or for comparison. Not even Deca can kick it out of receptor-sites!

Metribolone is highly resistant to binding proteins such as SHBG. This means it remains highly active in the blood. If you recall, about 97-99% of our testosterone is in a "bound" state and only the remaining 1-3% is active or free. Only free or active androgens can fit into receptor-sites and trigger the anabolic mechanism. Some AAS are more resistant to these binding proteins than others. And Metribolone is the most resistant of all. Like I said, a little goes a long way. As example consider this for a moment. If all other factors of potency were equal, 1mg of unbound/free Metribolone would have the same activity as 97-100mg of testosterone due to the effects of binding proteins.

*Metribolone is like "Super Parabolan". The few individuals I know who have tried it reported the stuff was nothing short of amazing. This is an injectable form of course. Since Metribolone has a brief active-life, daily injections were reported as necessary. With mega-dosage use liver damage is not just a high concern, it is a fact. Since this drug is like "Super Parabolan", all negative side effects, results, and uses of the two drugs are interchangeable for the most part, with the obvious exception of reported dosages. I have seen only a few vials of the SP Labs product available on the black market as of yet. However, there is an injectable around that claims to be made by Denkall. It is an underground lab product actually and the mcg/ml is suspect as is sterile factors. Personally, I did/would not use the drug. It just amazes me that it exists.


Wlliam Llewellyn (2011) - Anabolics
L. Rea (2002) - Chemical Muscle Enhancement Bodybuilders Desk Reference

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