GB-115 vs Trofinetide
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
Also: Ranquilon, N-phenylacetyl-L-prolylglycine ethyl ester
GB-115 is a synthetic dipeptide anxiolytic developed in Russia, chemically the amide of N-phenylhexanoyl-glycyl-L-tryptophan and described as a retro-analogue of cholecystokinin-4. Rather than acting like a benzodiazepine, it blocks cholecystokinin receptors, a different anti-anxiety route. It has been studied in animals and in a small pilot human study, but it is not an approved or widely available medication.
Also: Daybue, Daybue Stix
Trofinetide is a synthetic version of a tiny three-amino-acid fragment (glycine-proline-glutamate) that the body clips off IGF-1. It is the first drug ever approved for Rett syndrome: the FDA approved it as Daybue in March 2023 for patients 2 years and older, Health Canada followed in October 2024, and the EU authorised it as Daybu in August 2026 after first refusing it. It is a real, approved medicine with a real but modest effect, and the trade-off is blunt: most patients get diarrhea, and a meaningful share stop because of it.
Key Comparison Insights
- Trofinetide is FDA approved, while GB-115 remains in research stages.
- Both peptides belong to the Cognitive category, suggesting similar primary applications.
- Trofinetide has stronger research evidence (FDA Approved) compared to GB-115 (Human Trials).
Detailed Comparison
| Attribute | GB-115 | Trofinetide |
|---|---|---|
| Category | Cognitive | Cognitive |
| FDA Status | Not FDA Approved | FDA Approved |
| Clinical Status | Pre I II III IV FDA | Pre I II III IV FDA |
| Mechanism of Action | Cholecystokinin (CCK) is a peptide that acts as a neurotransmitter in the brain, and activating its CCK-2 (also called CCK-B) and CCK-1 receptors tends to trigger anxiety and panic-like states. GB-115 works as an antagonist at these cholecystokinin receptors, meaning it occupies the receptor and blocks CCK from setting off that anxiety signaling. In animal work it specifically prevented anxiety provoked by CCK-4, which shares a pharmacological target with GB-115. This CCK-blocking mechanism is the proposed explanation for its calming effect, and it is distinct from the GABA system that classic sedatives act on. | Rett syndrome is usually caused by loss-of-function mutations in the MECP2 gene, which disrupts how neurons mature and connect. Trofinetide is an analog of GPE, the N-terminal tripeptide of IGF-1, built to survive longer in the body than the natural fragment. In Mecp2-deficient mice, GPE partially reversed Rett-like symptoms, and the working theory is that trofinetide supports synaptic function and dampens neuroinflammation. The honest part: the FDA label states that the mechanism by which trofinetide works in Rett syndrome is unknown. It is taken by mouth in large gram-level doses, has an elimination half-life of about 1.5 hours, and is cleared mainly by the kidneys, which is why it is not recommended in moderate or severe kidney impairment. |
| Common Dosing | 6 mg daily (2 mg three times daily) 2-3 times daily (morning, afternoon, evening) | 5-12 g twice daily, set by body weight (labeled dose) Twice daily, morning and evening |
| Administration | Oral tablets or sublingual | Oral solution (200 mg/mL) by mouth or via gastrostomy tube; also available as a powder (Daybue Stix) mixed into liquid |
| Typical Duration | 21+ days in clinical trials, effects noted by day 7 | Ongoing for the approved indication; dose is interrupted, reduced, or stopped for severe diarrhea, dehydration, or significant weight loss |
| Best Time to Take | Morning and throughout the day | Morning and evening, as prescribed |
Possible Side Effects May vary by individual |
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| Research Summary | The research record is real but thin and almost entirely from a single Russian group. In rodent studies (rats, BALB/c and C57Bl/6 mice), GB-115 reduced anxiety induced by CCK-4 and by yohimbine, with effects that varied by mouse strain, and it stayed effective after long-term dosing without producing tolerance or a withdrawal syndrome when stopped. Preclinical safety work has also been published. The only human data comes from a small pilot clinical study of 25 patients with generalized anxiety disorder given 6 mg daily for 21 days, where anxiety scores on the Hamilton scale fell substantially and fatigue scores improved. Importantly, that study was a single-arm pilot with no placebo or control group, so it cannot prove the drug caused the improvement. There are no large randomized controlled trials, no Western regulatory approval, and the evidence base remains preliminary. | Approval rests on one pivotal trial, LAVENDER (Neul and colleagues, Nature Medicine 2023): 187 girls and young women aged 5 to 20 with Rett syndrome, randomized to trofinetide or placebo for 12 weeks. Both co-primary endpoints were hit. The caregiver-rated Rett Syndrome Behaviour Questionnaire improved by 4.9 points versus 1.7 on placebo, and the clinician-rated CGI-I score was 3.5 versus 3.8, with effect sizes in the small-to-moderate range (Cohen's d 0.37 and 0.47). A communication measure also favored the drug. The price was tolerability: diarrhea hit about 81% on trofinetide versus 19% on placebo, vomiting 27% versus 10%, and 17% dropped out for side effects (mostly diarrhea). The label adds that 12% lost more than 7% of body weight. Open-label extensions (LILAC and the 32-month LILAC-2, published in Med in 2024) reported continued improvement, but without a placebo arm those data cannot prove the drug caused it. In December 2025 the FDA approved Daybue Stix, a powder version, based on a bioequivalence study. In Europe, the EMA's committee first refused the application in February 2026, then recommended approval on re-examination in June 2026 for patients 5 and older, noting the improvements were small but relevant for a serious disease and that the trial showed no effect on seizures. Bottom line: a genuine first treatment for a disease that had none, with modest benefit and a heavy GI cost. |
Frequently Asked Questions: GB-115 vs Trofinetide
What is the difference between GB-115 and Trofinetide?
GB-115 is a cognitive peptide that gb-115 is a synthetic dipeptide anxiolytic developed in russia, chemically the amide of n-phenylhexanoyl-glycyl-l-tryptophan and described as a retro-analogue of cholecystokinin-4. rather than acting like a benzodiazepine, it blocks cholecystokinin receptors, a different anti-anxiety route. it has been studied in animals and in a small pilot human study, but it is not an approved or widely available medication. Trofinetide is a cognitive peptide that trofinetide is a synthetic version of a tiny three-amino-acid fragment (glycine-proline-glutamate) that the body clips off igf-1. it is the first drug ever approved for rett syndrome: the fda approved it as daybue in march 2023 for patients 2 years and older, health canada followed in october 2024, and the eu authorised it as daybu in august 2026 after first refusing it. it is a real, approved medicine with a real but modest effect, and the trade-off is blunt: most patients get diarrhea, and a meaningful share stop because of it. The main differences lie in their mechanisms of action and clinical applications.
Which is better, GB-115 or Trofinetide?
Neither is universally "better" - the choice depends on your specific goals. GB-115 is typically used for cognitive purposes, while Trofinetide is used for cognitive. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can GB-115 and Trofinetide be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using GB-115 and Trofinetide together should only be considered under medical supervision, as both compounds have their own side effect profiles and potential interactions. Research on their combined use may be limited.