chemistry

Onapristone

Onapristone is a chemistry 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 Onapristone rather than just read about it. In short: Onapristone (INNTooltip International Nonproprietary Name) (developmental code names ZK-89299, ZK-299) is a synthetic and steroidal antiprogestogen with additional antiglucocorticoid activity which was developed by Schering and described in 1984 but was never marketed. It is a silent antagonist of the progesterone receptor (PR), in contrast to the related antiprogestogen mifepristone (which is a weak partial agonist…

Key takeaways

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

Reference excerpt

Onapristone (INNTooltip International Nonproprietary Name) (developmental code names ZK-89299, ZK-299) is a synthetic and steroidal antiprogestogen with additional antiglucocorticoid activity which was developed by Schering and described in 1984 but was never marketed. It is a silent antagonist of the progesterone receptor (PR), in contrast to the related antiprogestogen mifepristone (which is a weak partial agonist of the receptor). Moreover, compared to mifepristone, onapristone has reduced antiglucocorticoid activity, shows little antiandrogenic activity, and has 10- to 30-fold greater potency as an antiprogestogen. The medication was under development for clinical use, for instance in the treatment of breast cancer and as an endometrial contraceptive, but was discontinued during phase III clinical trials in 1995 due to findings that liver function abnormalities developed in a majority patients. Onapristone has been found to be effective in the treatment of breast cancer. As of 2016, onapristone has re-emerged and is under development for the treatment of prostate cancer, currently in phase II clinical trials. It was also under development for the treatment of endometrial cancer, breast cancer, ovarian cancer, and uterine cancer, but was discontinued for these indications in favor of focusing on prostate cancer.

Chemistry

Synthesis The chemical synthesis has been described: Dof: Photoconversion patent: The more modern Chinese work starts from dienedione starting material: The name of the precursor goes by the trivial name of Ethylene deltenone [5571-36-8].

The conjugate addition reaction between PC10992393 (1) and 4-(n,n-Dimethyl)anilinemagnesium bromide [7353-91-5] (2) gives (3). Oxidation of the 17C alcohol group to a ketone gives [93748-54-0] (4). Irradiation for 16 minutes with a mercury lamp resulted in inversion of the methyl group from the beta to the alpha configuration, PC13371204 (5). Alkynylation with Tetrahydro-2-(2-propynyloxy)-2H-pyran [6089-04-9] (6) in the presence of butyl lithium gave (7). Catalytic hydrogenation then saturated the alkyne group whilst leaving the two olefins unperturbed. Acid removal of the cyclic ketal protecting group then completed the synthesis of onapristone (8).

See also List of investigational sex-hormonal agents § Progestogenics Aglepristone Lilopristone Telapristone Toripristone

References

Illustrations

Worked examples

Example 1 — a first encounter with Onapristone

Start with the simplest possible case. Write down what Onapristone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, 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 Onapristone 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 Onapristone 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 Onapristone

In research: Onapristone appears in chemistry 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 Onapristone 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: Onapristone is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1-Ethylcyclopentanols, Abortifacients, Antiglucocorticoids, so understanding it makes those chapters shorter.
In everyday life: Look for Onapristone 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 Onapristone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Onapristone 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 Onapristone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Onapristone in simple terms?

Why does Onapristone matter?

Because it connects several chemistry 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 Onapristone?

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 Onapristone.