chemistry

Risdiplam

Risdiplam 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 Risdiplam rather than just read about it. In short: Risdiplam, sold under the brand name Evrysdi, is a medication used to treat spinal muscular atrophy (SMA) and is the first oral medication approved to treat this disease by the US Food and Drug Administration (FDA). Risdiplam is a survival of motor neuron 2-directed RNA splicing modifier.

Key takeaways

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

Reference excerpt

Risdiplam, sold under the brand name Evrysdi, is a medication used to treat spinal muscular atrophy (SMA) and is the first oral medication approved to treat this disease by the US Food and Drug Administration (FDA). Risdiplam is a survival of motor neuron 2-directed RNA splicing modifier. In clinical trials, the most common adverse events included fever, diarrhea, rash, ulcers of the mouth area, joint pain (arthralgia) and urinary tract infections. Additional adverse events observed in the infantile-onset population included upper respiratory tract infection, pneumonia, constipation and vomiting. Risdiplam was approved for medical use in the United States in August 2020. Developed by Roche in Basel, Switzerland, in association with PTC Therapeutics and the SMA Foundation, it is marketed in the US by Genentech, a subsidiary of Roche. In February 2025, the FDA approved a new tablet formulation of risdiplam.

Medical uses In the United States, risdiplam is indicated to treat people with spinal muscular atrophy. It has been used to treat a baby in utero. The parents had previously suffered the death of a child due to spinal muscular atropy. The FDA approved the use of this agent in pregnancy and it was started at 32 weeks gestation. The baby was delivered at 38 weeks gestation and has continued on this agent until the age of 2.5 years. During this period there have been no signs of spinal muscle atrophy.

Adverse effects In two clinical trials, the following adverse events occurred at least 5% more frequently in participants treated with risdiplam than in the placebo group: fever, diarrhea, rash, ulcers of the mouth area, joint pain (arthralgia) and urinary tract infections. Additional adverse events for the infantile-onset population included upper respiratory tract infection, pneumonia, constipation and vomiting. Risdiplam may increase the plasma concentrations of medications that are multidrug and toxin extrusion (MATE) substrates.

Pharmacology

Mechanism of action Risdiplam addresses the underlying cause of SMA: a reduced amount of survival motor neuron (SMN) protein. The protein is encoded by the SMN1 and SMN2 genes. SMA is caused by mutations in SMN1 that code for inactive forms of the protein. The activity of the SMN2 gene, which produces much smaller quantities of SMN, tends to determine the severity of disease. The compound is a pyridazine derivative that modifies the splicing of SMN2 messenger RNA to include exon 7, resulting in an increase in the concentration of the functional SMN protein in vivo. Nusinersen, the first drug approved to treat SMA, an anti-sense oligonucleotide targeting intronic splicing silencer N1 (ISS-N1), also alters mRNA splicing of SMN2. Risdiplam is classified as an aminocyclopropane.

Efficacy The safety and efficacy of risdiplam in infantile-onset and later-onset SMA has been evaluated in ongoing clinical trials. In the infantile-onset SMA study, an open-label trial with 41 participants, efficacy was established based on the ability to sit without support for at least five seconds. After 12 months of treatment, 29% of participants were able to sit independently for more than five seconds. After 23 or more months of treatment, 81% of participants were alive without permanent ventilation. Although the study did not perform direct comparisons against children receiving a placebo (inactive treatment), these results compare favourably with the typical course of the untreated disease. The study of later-onset SMA was a randomised controlled trial that enrolled 180 participants, aged between 2 and 25 years, with less severe forms of the disease. Participants treated with risdiplam for 12 months showed improvements in motor function compared to participants given a placebo.

Society and culture

Legal status The US Food and Drug Administration (FDA) awarded marketing approval to Genentech in August 2020. The FDA earlier granted the application for risdiplam fast track, priority review, and orphan drug designations. Genentech was also awarded a rare pediatric disease priority review voucher. The European Medicines Agency (EMA) awarded risdiplam a priority medicine designation in 2018 and an orphan drug designation in 2019.

Names Risdiplam is the international nonproprietary name (INN).

Compassionate use Since 2019, Roche has been offering the drug globally for free to some eligible people through an expanded access program.

References

Illustrations

Worked examples

Example 1 — a first encounter with Risdiplam

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

In research: Risdiplam 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 Risdiplam 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: Risdiplam is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cyclopropanes, Drugs developed by Genentech, Drugs developed by Hoffmann-La Roche, so understanding it makes those chapters shorter.
In everyday life: Look for Risdiplam 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 Risdiplam in 20 minutes

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

Frequently asked questions

What is Risdiplam in simple terms?

Why does Risdiplam 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 Risdiplam?

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 Risdiplam.