Peptide basics

Semax vs selank: two heavily read compounds with no registered trials at all

This page reports what the trial registry, the FDA compounding record and PubMed contain for two compounds. It makes no statement about cognitive or mood effects, and the absence of registered trials described below is a fact about the public record rather than a finding about the molecules.

What this comparison measures

This page compares what is publicly recorded for two compounds: registered studies, phases, regulatory standing, indexed publications and readership. On the first two of those, the answer for both compounds is nothing at all, and that is the finding rather than an omission.¹²³⁴

Registered human trials

In the snapshot of 1 August 2026, a registry search for semax returned no matches at all. A search for selank returned two loose matches, and neither survived verification.¹²

The two selank matches are worth naming, because they are the clearest illustration on this site of why a raw registry count cannot be published as an evidence count. One is a trial comparing transcranial direct-current stimulation with transcranial random-noise stimulation for reading skills. The other studies transcranial magnetic stimulation and object recognition. Neither administers selank; both matched on text.¹⁰¹¹²

• Semax: 0 raw registry matches, 0 verified.
• Selank: 2 raw registry matches, 0 verified.
• Neither compound has a phase label, because a phase requires a registered study to attach to.¹²

Regulatory status

Neither compound has an approved US product in the snapshot. Both appear on FDA's published page for bulk drug substances nominated for use in compounding, in the table of nominations later withdrawn by their nominators, listed as semax (heptapeptide) and as selank acetate (TP-7).⁵

FDA's wording for both is an absence rather than a finding. For semax the agency records no or limited safety-related information for the proposed routes and states that it therefore lacks sufficient information to know whether harm would result. For selank acetate it records that it lacks important information about any safety issues raised.⁵

Publication trend, 2017 to 2026

A PubMed title/abstract search across 2017 to 2026 returns 53 records for semax and 19 for selank. Semax runs between 3 and 9 records a year with no trend; selank records zero in three of the ten years and has not exceeded 8.³⁴

The composition of those literatures matters more than the totals. Representative recent entries include a rat study of semax described in its title as a synthetic ACTH(4-10) analogue, and a rat study of selank described as a peptide analogue of tuftsin. Both compounds are characterised chemically in the literature; that characterisation is not clinical evidence.⁷⁸

A 2021 clinical-pharmacology review of agents acting at GABA receptors includes selank among its subjects, which is one of the few English-language secondary treatments of the compound.⁹

The one human study that administers both

A 2020 paper reports a placebo-controlled imaging study in 52 healthy participants in which both selank and semax were administered and resting-state functional connectivity was measured before and after. It is the only published work located here in which both compounds appear in the same protocol.⁶

It also illustrates the limit of registry-based counting. A study can be conducted and published without appearing in ClinicalTrials.gov, particularly outside the jurisdictions where registration is a condition of publication or funding. A count of zero registered studies means zero registrations, not zero research.⁶¹²

Semax has no registered trial and roughly three times selank's indexed publication count.

Selank has no registered trial either, and its two registry matches are studies of brain stimulation that never administer it.

Attention against evidence

Between February and July 2026, the semax Wikipedia article averaged 14,065 views a month and peaked at 16,303; the selank article averaged 6,791 and peaked at 8,078.¹²¹²

Roughly twenty-one thousand readers a month, across two compounds with no registered trials between them, is the widest attention-to-evidence gap in the cognitive category on this site. It says nothing about the compounds and everything about where public interest sits relative to the record.¹²¹²

Common questions