Skip to content
Peptide Insider

Methodology

How we grade the evidence

Peptide Insider applies one evidence taxonomy across every compound on the site, from FDA-approved drugs to research chemicals. This page defines each level, states what it does not mean, and explains why the system is built this way.

Why a taxonomy at all

The central problem in peptide information is not that facts are missing. It is that different kinds of evidence get presented in the same voice. A rodent study, a Phase 1 hormone measurement and a 17,000-participant outcomes trial all end up as “studies show”.

A fixed taxonomy forces the distinction into view. Every compound on this site carries a label, the labels are defined in advance, and the same definitions are applied whether the compound is an approved medicine or something sold in a vial online.

Two separate scales

We grade two different things, because they answer different questions and can diverge:

  • Evidence level — how much human evidence exists, and of what quality.
  • Research status — where the compound sits in the development pipeline.

A compound can be Investigational (status) while rated EARLY CLINICAL (evidence). An approved drug can still be rated INSUFFICIENT for a specific off-label research question. One number could not carry both.

Evidence levels

CLINICAL

4 compounds currently rated CLINICAL

Multiple adequately powered randomised controlled trials in humans, with published results.

CriteriaAt least two adequately powered, randomised, controlled human trials with published peer-reviewed or regulator-reviewed results, reporting pre-specified primary endpoints. Typically applies to compounds that have completed Phase 3 development or hold a marketing authorisation for at least one indication.

What it does not meanIt does not mean the compound is safe or effective for every use. A CLINICAL rating attaches to the research programme, not to any individual reader or any use outside the studied indications.

EARLY CLINICAL

3 compounds currently rated EARLY CLINICAL

Human trials exist but are small, early phase, single-site, or limited to surrogate endpoints.

CriteriaOne or more completed human studies — typically Phase 1 or Phase 2, small sample sizes, short duration, surrogate or biomarker endpoints, or narrow populations. Results may be promising but have not been replicated at scale.

What it does not meanIt does not mean clinical benefit has been demonstrated. Most compounds that look promising at this stage do not go on to succeed in larger trials.

PRECLINICAL

2 compounds currently rated PRECLINICAL

Evidence is confined to animal models, tissue, or cell-culture work. No meaningful human data.

CriteriaA body of published animal, ex vivo or in vitro research exists, but there are no completed, published, controlled human trials of the compound for the research areas described.

What it does not meanAnimal findings frequently fail to reproduce in humans. A PRECLINICAL rating is a statement about where the research currently stops, not a prediction that it will continue successfully.

LIMITED

1 compound currently rated LIMITED

Only a small number of studies exist, or the available studies have serious methodological limits.

CriteriaPublished research exists but is sparse, concentrated in a single research group, uncontrolled, retrospective, or otherwise subject to a high risk of bias. Also applied where the published record is dominated by case reports or open-label observation.

What it does not meanIt does not mean the compound has been shown not to work. It means the published record is currently too thin to support a conclusion in either direction.

INSUFFICIENT

0 compounds currently rated INSUFFICIENT

There is not enough published, independently verifiable research to characterise the compound.

CriteriaNo substantial body of peer-reviewed literature is available, or the literature that exists does not address the questions readers are asking. Frequently applies to compounds that circulate widely online with far more marketing material than research behind them.

What it does not meanIt is not a safety rating. An INSUFFICIENT rating means unknown, and unknown includes unknown risks.

Research status

FDA Approved

3 compounds

Approved by the U.S. Food and Drug Administration for at least one specific indication.

The compound is the active ingredient in at least one drug product with FDA marketing authorisation. Approval is always indication-specific: a compound approved for one condition is not approved for others.

Investigational

2 compounds

In active clinical development under regulatory oversight, but not approved.

The compound is the subject of registered clinical trials under an active development programme. It has not received marketing authorisation and cannot lawfully be marketed for the treatment of disease.

Clinical Research

3 compounds

Studied in humans at some point, but not part of an active approval pathway.

Human studies have been conducted and published, but there is no current, publicly disclosed programme working toward approval — development may have been discontinued, shelved, or never resumed.

Preclinical Research

2 compounds

Studied in animals, tissue or cell models only.

The published research record is confined to non-human work. The compound has not been evaluated in controlled human trials.

Limited Evidence

0 compounds

Discussed widely, but with little published research of any kind behind it.

The compound circulates in consumer or grey-market channels without a corresponding body of published research. Claims made about it typically outrun the literature by a wide margin.

The limits of this system

A rating is a judgement, made by people, about a body of literature that is usually incomplete. Three specific limitations are worth stating:

  • Publication bias. Negative results are published less often than positive ones. A literature that looks consistently favourable may be consistently incomplete.
  • Concentration. Where most research on a compound comes from a single group, the literature has not been independently stress-tested regardless of its size. We note this on profiles where it applies.
  • Boundaries are judgements. The line between EARLY CLINICAL and PRECLINICAL sometimes requires a call. We make it conservatively — when a compound sits between two levels, we assign the lower one and explain why on the page.

If you think a rating on this site is wrong, tell us and say which source contradicts it. That is how our corrections process works.

Questions about the ratings

Is a CLINICAL rating a recommendation?
No. Every rating on this site describes the published research record and nothing else. A CLINICAL rating means adequately powered randomised human trials exist and have been published. It is not a statement that a compound is suitable, safe or advisable for any individual.
Why do some compounds have different ratings for different research areas?
Because the evidence genuinely differs by area. Thymosin β4 has randomised human trial evidence for topical ocular use and none for systemic musculoskeletal repair. Collapsing that into a single number would hide the most important thing a reader needs to know, so every profile grades each research area separately.
Why not use star ratings?
Stars imply a score out of five and invite the reading “four stars is good”. Evidence quality is not a score, and a compound with strong evidence of no effect would rate highly on any star scale. Named tiers force the label to describe what kind of evidence exists rather than how favourable it is.
Does INSUFFICIENT mean a compound does not work?
No. It means the published record is too thin to support a conclusion in either direction. Unknown includes unknown risks as well as unknown benefits, which is why we treat INSUFFICIENT as a reason for caution rather than a neutral state.
How often are ratings reviewed?
Every profile shows its last reviewed date. Ratings are revisited on a rolling basis and out of cycle whenever a regulatory decision, trial readout or significant publication would change them.