How peptide evidence levels work: what a 1 to 5 rating means

The five levels

• 1. Limited, preclinical or single-group data.
• 2. Mostly animal and in vitro studies.
• 3. Early human trials.
• 4. Late-stage human trials.
• 5. Approved drug with phase 3 programmes.

What moves a rating

Independent replication, controlled human trials, larger sample sizes and regulatory review move a compound up. Retractions, failed replication and safety signals move it down.

What the rating does not mean

It is not a recommendation. A level 5 compound has been studied extensively in approved medicinal forms; that says nothing about research-grade material or any use outside regulated medicine. A level 2 compound is not worthless, just less well characterised.

Where the ratings are used

Ratings appear on compound pages, in the comparison tool, in the peptide finder and in the statistics, which report how many compounds sit at each level.

Editorial independence

Ratings are not adjusted for stock or price. Compounds Nordapep does not list are rated the same way. See the editorial policy for the full separation between editorial and commercial content.