Daybue (trofinetide)
An approved treatment for Rett Syndrome.
The same compound appears under different names depending on the context. Here is how to identify Trofinetide wherever you encounter it, plus the key facts at a glance.
- Generic name
- Trofinetide
- Brand name
- Daybue
- Development code
- NNZ-2566
- Drug class
- IGF-1 analog
- Manufacturer
- Acadia Pharmaceuticals
- How it's taken
- Taken by mouth twice daily as an oral solution or powder mixed with water.
The first and only FDA-approved treatment for Rett syndrome. Trofinetide is thought to reduce brain inflammation and support nerve cell communication, though the label states its exact mechanism in Rett syndrome is unknown. It is approved for patients aged 2 and older.
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Where Trofinetide fits
First and only FDA-approved therapy specifically for Rett syndrome. Addresses core symptoms including communication difficulties and repetitive hand movements.
How Trofinetide works
Trofinetide mimics a fragment of a natural growth hormone called IGF-1 that supports brain cell health. In Rett syndrome, brain cells struggle to communicate properly and become inflamed. Trofinetide helps calm this inflammation and restore signaling between neurons, leading to improvements in daily function and behavior.
Mechanism: Synthetic analog of the amino-terminal tripeptide of insulin-like growth factor-1 (IGF-1) that reduces neuroinflammation and supports synaptic function
Side effects and safety
The most common side effect is diarrhea, affecting about 80-85% of patients, though most cases are mild to moderate. Vomiting occurs in about 27-29% of patients. Some patients experience weight loss, so weight should be monitored. Vomiting can lead to vomit getting into the lungs (aspiration) and aspiration pneumonia, so tell your doctor if vomiting is severe or frequent. Stop laxatives before starting. Your doctor may pause, lower, or stop the dose if side effects are severe.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Trofinetide
Taken by mouth twice daily as an oral solution or powder mixed with water. Dosing is based on body weight, ranging from 5g to 12g per dose. Can also be given through a gastrostomy (G-tube). A powder formulation (Daybue Stix) was approved in 2025 for easier preparation.
Availability and cost
Only available as the brand-name product.
First and only FDA-approved treatment for Rett syndrome, an ultra-rare neurological condition. Orphan drug for an extremely small patient population with no prior approved therapies.
Help paying for Daybue
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Eligible commercially insured patients may pay as little as $0 per month, with automatic enrollment in the Acadia Connect Commercial Copay Program. Program maximums apply; not for government insurance.
For: private insurance · source - Other support
If you have no insurance or your plan does not cover DAYBUE, Acadia Connect may offer options such as its Patient Assistance Program. Application and review required.
For: no insurance · source - Insurance and case manager help
Family Support Educator, Nurse Care Coordinator and Patient Access Manager help with insurance coverage, benefits checks and delivery through AnovoRx specialty pharmacy.
For: private insurance, Medicare, Medicaid, TRICARE, no insurance, underinsured · source
Good to know: The official pages do not say the Patient Assistance Program gives medicine for free or what the income limits are. Call Acadia Connect for details.
- From a charity · The Assistance FundRett Syndrome fundOpen
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “OPEN — Accepting New Patients. TAF is currently accepting new patient enrollments for this program.” - From a charity · TotalAssist (formerly PAN Foundation)Rett Syndrome fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $4,400 per year. Requires health insurance (any kind).
- From a charity · NORD RareCareRett Syndrome Emergency Relief Assistance fundWaitlist
Pays for: Emergency relief.
The foundation says: “Temporarily Waitlisting”
Clinical trial results
The Phase 3 LAVENDER trial enrolled 187 female patients aged 5-20 and met both primary endpoints. Patients on trofinetide showed significant improvement on the Rett Syndrome Behaviour Questionnaire (RSBQ) and Clinical Global Impression-Improvement (CGI-I) compared to placebo over 12 weeks.
Development history
Trofinetide was developed by Neuren Pharmaceuticals and licensed to Acadia Pharmaceuticals for North America. It received FDA approval in March 2023, becoming the first treatment specifically approved for Rett syndrome. A powder formulation was approved in December 2025.
Explore Rett Syndrome trials
Other Rett Syndrome treatments
Trofinetide in Trial Friend News and Guides
Common questions about Trofinetide
▸What is Trofinetide (Daybue)?
The first and only FDA-approved treatment for Rett syndrome. Trofinetide is thought to reduce brain inflammation and support nerve cell communication, though the label states its exact mechanism in Rett syndrome is unknown. It is approved for patients aged 2 and older.
▸How does Trofinetide work?
Trofinetide mimics a fragment of a natural growth hormone called IGF-1 that supports brain cell health. In Rett syndrome, brain cells struggle to communicate properly and become inflamed. Trofinetide helps calm this inflammation and restore signaling between neurons, leading to improvements in daily function and behavior.
▸What are the side effects of Trofinetide?
The most common side effect is diarrhea, affecting about 80-85% of patients, though most cases are mild to moderate. Vomiting occurs in about 27-29% of patients. Some patients experience weight loss, so weight should be monitored. Vomiting can lead to vomit getting into the lungs (aspiration) and aspiration pneumonia, so tell your doctor if vomiting is severe or frequent. Stop laxatives before starting. Your doctor may pause, lower, or stop the dose if side effects are severe.
▸How is Trofinetide taken?
Taken by mouth twice daily as an oral solution or powder mixed with water. Dosing is based on body weight, ranging from 5g to 12g per dose. Can also be given through a gastrostomy (G-tube). A powder formulation (Daybue Stix) was approved in 2025 for easier preparation.
▸Is Trofinetide FDA approved?
Yes, Trofinetide (Daybue) is FDA approved (2023) for the treatment of Rett Syndrome.
▸Is trofinetide a cure for Rett syndrome?
No. Trofinetide (Daybue) is not a cure. It does not fix the underlying MECP2 gene mutation that causes Rett syndrome. Instead, it treats the downstream effects of the mutation by supporting brain cell health, reducing neuroinflammation, and improving synaptic function. Patients must continue taking it to maintain its benefits. It is the first FDA-approved treatment specifically for Rett syndrome.
▸How does trofinetide compare to the gene therapy approaches for Rett?
Trofinetide is an oral medication that treats the downstream consequences of MECP2 deficiency without addressing the gene itself. Gene therapies like NGN-401 and TSHA-102 aim to deliver a working copy of the MECP2 gene to brain cells, potentially offering a more fundamental correction. However, gene therapies are still investigational and carry risks including the need for surgical delivery. Trofinetide is available now as an approved daily treatment, while gene therapies remain in clinical trials.
▸What improvements can families expect with trofinetide?
In the LAVENDER Phase 3 trial, patients taking trofinetide showed improvements in clinician-assessed overall severity and caregiver-assessed quality of daily life compared to placebo. Specific areas of improvement can include hand function, communication, and overall responsiveness. Results vary between individuals, and improvements tend to be gradual. Not all patients will respond, and the degree of benefit differs from person to person.
▸Why does trofinetide commonly cause diarrhea?
Diarrhea is the most frequent side effect of trofinetide, affecting a significant proportion of patients. The drug is a synthetic analog of a naturally occurring peptide (IGF-1 tripeptide), and its mechanism of action in the gut may contribute to gastrointestinal effects. In clinical trials, the diarrhea was generally manageable and often improved over time. Dose adjustments and supportive care can help manage this side effect. Families should work with their physician to find the best approach.
▸What age can patients start trofinetide?
Trofinetide is FDA-approved for patients aged 2 years and older with Rett syndrome. The oral solution formulation allows weight-based dosing for younger children. There is no upper age limit specified in the prescribing information, and adult patients with Rett syndrome may also benefit from treatment.
▸How is trofinetide administered?
Trofinetide is taken twice daily, morning and evening, as an oral solution (Daybue) or as Daybue Stix powder packets dissolved in water or a water-based drink. The dose is based on body weight. It can be given by mouth or through a gastrostomy tube (G-tube). Both forms are strawberry flavored. The Daybue liquid is stored upright in the refrigerator; Daybue Stix packets are stored at room temperature.