earth science

Metribolone

Metribolone is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Metribolone rather than just read about it. In short: Metribolone (developmental code R1881, also known as methyltrienolone) is a synthetic and orally active anabolic–androgenic steroid (AAS) and a 17α-alkylated nandrolone (19-nortestosterone) derivative which was never marketed for medical use but has been widely used in scientific research as a hot ligand in androgen receptor (AR) ligand binding assays (LBAs) and as a photoaffinity label for the AR. More precisely, m…

Key takeaways

Metribolone belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Metribolone to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Metribolone from memory before moving on to harder problems.

Reference excerpt

Metribolone (developmental code R1881, also known as methyltrienolone) is a synthetic and orally active anabolic–androgenic steroid (AAS) and a 17α-alkylated nandrolone (19-nortestosterone) derivative which was never marketed for medical use but has been widely used in scientific research as a hot ligand in androgen receptor (AR) ligand binding assays (LBAs) and as a photoaffinity label for the AR. More precisely, metribolone is the 17α-methylated derivative of trenbolone. It was investigated briefly for the treatment of advanced breast cancer in women in the late 1960s and early 1970s, but was found to produce signs of severe hepatotoxicity at very low dosages, and its development was subsequently discontinued.

Medical uses Metribolone was never approved for medical use, a situation unlikely to change given its liver toxicity even at low doses. It was studied for the potential treatment of advanced breast cancer in women but development was abandoned.

Side effects

Side effects of metribolone include virilization and hepatotoxicity among others.

Pharmacology

Pharmacodynamics Metribolone is an AAS, or an agonist of the AR, with both anabolic and androgenic activity. It is one of the most potent AAS to have ever been synthesized, with 120 to 300 times the oral anabolic potency and 60 to 70 times the androgenic potency of the reference AAS methyltestosterone in castrated male rats, although the same level of potency has not been observed in studies in humans. In addition to the AR, metribolone has high affinity for the progesterone receptor (PR), and binds to the glucocorticoid receptor (GR) as well. The drug was also identified in 2007 as a potent antimineralocorticoid, with similar affinity for the mineralocorticoid receptor as aldosterone and spironolactone. In addition, metribolone was identified in 2010 as a potent inhibitor of 3β-hydroxysteroid dehydrogenase (3β-HSD) 1 and 2 (IC50 = 0.02 and 0.16 μM, respectively). On the basis of this finding, it has been said that metribolone should be used very cautiously in scientific research, taking into account 3β-HSD inhibition to avoid erroneous interpretation. Metribolone has a high potential for hepatotoxicity, similarly to other 17α-alkylated AAS. However, the hepatotoxic potential of metribolone appears to be exceptionally high, likely in relation to its very high potency and metabolic stability; in a study of treatment with the drug for advanced breast cancer, severe hepatic dysfunction was observed at very low dosages.

Pharmacokinetics Metribolone 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 dihydrotestosterone (DHT).

Chemistry

Metribolone, also known as 17α-methyltrenbolone, as well as 17α-methyl-δ9,11-19-nortestosterone or 17α-methylestra-4,9,11-trien-17β-ol-3-one, is a synthetic estrane steroid and a 17α-alkylated derivative of nandrolone (19-nortestosterone). It is the C17α methylated derivative of trenbolone (δ9,11-19-nortestosterone) and the C9- and C11-dehydrogenated (δ9,11) analogue of normethandrone (17α-methyl-19-nortestosterone). Other close relatives and derivatives of metribolone include mibolerone (7α,17α-dimethyl-19-nortestosterone) and dimethyltrienolone (RU-2420; 7α,17α-dimethyl-δ9,11-19-nortestosterone). In addition to AAS, trimethyltrienolone (R2956; 2α,2β,17α-trimethyl-δ9,11-19-nortestosterone), a highly potent antiandrogen, has been derived from metribolone.

History Metribolone was first described in the literature in 1965. It was studied clinically in the late 1960s and early 1970s, most notably in the treatment of advanced breast cancer. The drug was found to be effective and showed weak androgenicity, but also produced severe signs of hepatotoxicity, and was ultimately never marketed. By the mid-1970s, metribolone was becoming an accepted standard as a ligand and agonist of the AR in scientific research. It remains in wide use for this purpose today. Aside from scientific research, metribolone has also been encountered as an AAS in non-medical contexts, for instance in doping in sports and bodybuilding.

Society and culture

Generic names Metribolone is the generic name of metribolone and its INNTooltip International Nonproprietary Name. It is also known by the name methyltrienolone and its developmental code names R1881, R-1881, RU-1881, and RU1881, and is very commonly referred to by these other names rather than as metribolone in the scientific literature.

Doping in sports Prior to the 2008 Beijing Olympic Games, 11 members of the Greek national weightlifting team and 4 Greek track and field athletes tested positive for metribolone.

References

External links Metribolone at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Methyltrienolone - William Llewellyn's Anabolic.org Archived 2016-04-07 at the Wayback Machine

Illustrations

Worked examples

Example 1 — a first encounter with Metribolone

Start with the simplest possible case. Write down what Metribolone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Metribolone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Metribolone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Metribolone

In research: Metribolone appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Metribolone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Metribolone is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3β-Hydroxysteroid dehydrogenase inhibitors, Abandoned drugs, Androgens, so understanding it makes those chapters shorter.
In everyday life: Look for Metribolone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Metribolone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Metribolone means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Metribolone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Metribolone in simple terms?

Why does Metribolone matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Metribolone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Metribolone.