Plain-English fact sheet
Trofinetide
Also known as Daybue, NNZ-2566
Trofinetide is the first FDA-approved medicine for Rett syndrome. Its benefit is specific to that condition and must be read alongside common diarrhea, vomiting, and weight-loss risks.
Quick answer
Trofinetide is FDA approved as Daybue for Rett syndrome in adults and children 2 years and older. It is not approved as a general cognitive, developmental, neuroprotective, or anti-aging peptide.
By the PeptideFactSheets Editorial Team. Use the source links to verify status, evidence, risks, and unknowns; our editorial policyexplains the boundaries. Clinician review appears only when a named reviewer is shown.
What is Trofinetide?
Trofinetide is a synthetic analog of glycine-proline-glutamate, a three-amino-acid fragment related to insulin-like growth factor 1 biology.
The approved claim rests on changes in caregiver- and clinician-rated Rett syndrome measures, not a cure or reversal of the condition.
Why are people interested in it?
Rett syndrome is a rare neurodevelopmental disorder with major communication, movement, and daily-function effects.
Its approval shows that a very small peptide analog can become a condition-specific neurology medicine, but does not validate broader brain-enhancement claims.
Current regulatory status
FDA-approved Daybue labeling covers treatment of Rett syndrome in adults and pediatric patients 2 years of age and older.
What is it approved for?
- Treatment of Rett syndrome in adults and pediatric patients 2 years of age and older under the Daybue label
FDA approval path
FDA approved for Rett syndrome
Trofinetide is approved under the Daybue label for Rett syndrome in specified ages. The approval should not be generalized to other neurodevelopmental or cognitive claims.
Step 7 of 7
- DiscoveryBasic research
- PreclinicalLab and animal work
- Phase 1Initial human testing
- Phase 2Condition-focused trials
- Phase 3Confirmatory trials
- FDA reviewApplication review
- ApprovedLabel-specific use
What is it being studied for?
Investigational areas
- Longer-term Rett syndrome outcomes and functional effects
Evidence snapshot
A randomized Phase 3 trial supported statistically significant but modest changes on Rett-specific symptom scales. Evidence is condition-specific and does not establish restoration of lost function or benefit in other neurologic disorders.
Potential benefits being researched
- The pivotal trial found better average change than placebo on a caregiver-rated Rett symptom score and a clinician global-impression measure.
- The trial did not establish a cure, disease reversal, or benefit outside Rett syndrome.
Potential does not mean proven. Study design, population, endpoint, and regulatory review matter.
Known or possible risks
- Diarrhea and vomiting are prominent labeled adverse reactions and can be severe.
- The label warns about weight loss and the need for clinical monitoring.
- Long-term real-world effectiveness and tolerability may differ from the pivotal trial.
What we still do not know
- Durability of functional benefit over many years
- Which individual characteristics predict meaningful response
- Effects on outcomes not captured well by the pivotal rating scales
- Whether related peptide analogs could help other neurodevelopmental disorders
Plain-English takeaway
Trofinetide is a genuine rare-neurology peptide medicine, not a broad cognitive enhancer. The average trial benefit was modest and gastrointestinal tolerability is central to its benefit-risk picture.
Research and reference links
Use these primary and reputable sources to verify status and read beyond this summary. Trial registries may list studies without proving a benefit.
- 1fdaFDA prescribing information: Daybue
Current approved indication, warnings, adverse reactions, and pivotal-study summary.
- 2pubmedLAVENDER randomized Phase 3 trial
Pivotal controlled study of Rett-specific symptom and global-impression outcomes.
- 3fdaFDA multidisciplinary review: Daybue
FDA review of efficacy, safety, trial interpretation, and approval considerations.