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. Claims are source-checked under our editorial policy; clinician review is identified 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
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.
- 1FDA prescribing information: Daybue
Current approved indication, warnings, adverse reactions, and pivotal-study summary.
- 2LAVENDER randomized Phase 3 trial
Pivotal controlled study of Rett-specific symptom and global-impression outcomes.
- 3FDA multidisciplinary review: Daybue
FDA review of efficacy, safety, trial interpretation, and approval considerations.