chemistry

Samidorphan

Samidorphan 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 Samidorphan rather than just read about it. In short: Samidorphan (INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name) is an opioid antagonist that in the form of olanzapine/samidorphan (sold as Lybalvi) is used in the treatment of schizophrenia and bipolar disorder. Samidorphan reduces the weight gain associated with olanzapine.

Key takeaways

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

Reference excerpt

Samidorphan (INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name) is an opioid antagonist that in the form of olanzapine/samidorphan (sold as Lybalvi) is used in the treatment of schizophrenia and bipolar disorder. Samidorphan reduces the weight gain associated with olanzapine. Samidorphan is taken by mouth. Samidorphan was under development as a standalone medication for various indications but has been discontinued. Buprenorphine/samidorphan for the treatment of major depressive disorder was rejected by the US Food and Drug Administration (FDA) due to insufficient evidence of effectiveness, but remains in preregistration as of September 2021. Development of baclofen/samidorphan has also been discontinued.

Development Samidorphan has been investigated for the treatment of alcoholism and cocaine addiction by its developer, Alkermes, showing similar efficacy to naltrexone, but possibly with reduced side effects. It has attracted much more attention as part of the combination product (buprenorphine/samidorphan), where samidorphan is combined with the mixed μ-opioid receptor (MOR) weak partial agonist and κ-opioid receptor (KOR) antagonist buprenorphine, as an antidepressant. Buprenorphine has shown antidepressant effects in some human studies, thought to be because of its antagonist effects at the KOR, but has not been further developed for this application because of its MOR agonist effects and consequent abuse potential. By combining buprenorphine with samidorphan to block the MOR agonist effects, the combination acts more like a selective KOR antagonist, and produces only antidepressant effects, without typical MOR effects such as euphoria or substance dependence being evident. Samidorphan was also studied in combination with olanzapine, (olanzapine/samidorphan), for use in schizophrenia. A Phase III study found that the addition of samidorphan to olanzapine significantly reduced weight gain compared to olanzapine alone, and the combination was approved for the treatment of schizophrenia and bipolar disorder by the FDA in May 2021, under the brand name Lybalvi.

Side effects Side effects of samidorphan include somnolence and gastrointestinal disturbances among others.

Pharmacology

Pharmacodynamics

Samidorphan acts primarily as an antagonist or very weak partial agonist of the μ-opioid receptor (MOR) and to a lesser extent as a partial agonist of the κ-opioid receptor (KOR) and δ-opioid receptor (DOR). In accordance with this profile, samidorphan has been observed to produce some side effects that are potentially consistent with activation of the KOR such as somnolence, sedation, dizziness, and hallucinations in some patients in clinical trials.

Pharmacokinetics The elimination half-life of samidorphan is 7 to 9 hours.

Chemistry Samidorphan has its origins in academia where 8-carboxamidocyclazocine and naltrexone were utilized in its design and synthesis.

References

Illustrations

Worked examples

Example 1 — a first encounter with Samidorphan

Start with the simplest possible case. Write down what Samidorphan 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 Samidorphan 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 Samidorphan 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 Samidorphan

In research: Samidorphan 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 Samidorphan 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: Samidorphan is common in secondary-school and first-year university syllabi. It links to neighbouring topics Abandoned drugs, Cyclopropyl compounds, Delta-opioid receptor agonists, so understanding it makes those chapters shorter.
In everyday life: Look for Samidorphan 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 Samidorphan in 20 minutes

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

Frequently asked questions

What is Samidorphan in simple terms?

Why does Samidorphan 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 Samidorphan?

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 Samidorphan.