The Nordapep blog
Plain-English guides to buying, testing, storing and preparing research peptides — written for researchers working with our catalogue.
29 articles
Retatrutide Clinical Trial Results: Phase 2 to the TRIUMPH Phase 3 Programme
Retatrutide has two Phase 2 trials behind it and, by Lilly’s count, six positive Phase 3 studies: four in the TRIUMPH programme and two in the TRANSCEND diabetes programme.
Retatrutide Side Effects: What the Clinical Trials Actually Reported
In Lilly’s trials, retatrutide’s adverse events are mostly gastrointestinal and rise with dose. The one signal that stands apart from comparable drugs is dysaesthesia (reported as dysesthesia in Lilly’s US releases), an abnormal skin sensation.
Retatrutide vs Tirzepatide vs Semaglutide: What the Trial Data Can and Cannot Tell You
Retatrutide has produced among the largest mean weight losses reported in a Phase 3 obesity trial: 28.3% at 80 weeks on the efficacy estimand, against 22.5% for tirzepatide and 14.9% for semaglutide in their pivotal trials.
Retatrutide Regulatory Status and Research-Material Quality: What to Check
Retatrutide is not approved by any regulator. Lilly plans to file with the FDA in the first quarter of 2027, the FDA and the UK’s MHRA have both said that products sold as retatrutide outside clinical trials are unauthorised, and the market is full of material of unknown quality.
Retatrutide: what the label and CoA should show
What retatrutide is as a molecule, the figures a Certificate of Analysis should carry for it, and the checks worth doing before a vial or pen goes anywhere near a protocol.
GHK-Cu: properties and handling in the lab
Why GHK-Cu is blue, how it differs from plain GHK on a certificate, and what to know about dissolving and storing a copper peptide.
Melanotan I and Melanotan II: how the two molecules differ
Two melanocortin peptides with similar names and different structures. How to tell them apart on paper, and why the certificate has to match the right one.
Selank: structure, mass and documentation
A short heptapeptide with a well-defined sequence. What its certificate should show and what general handling practice looks like.
A checklist for when your peptide order arrives
Ten minutes of checks when a parcel arrives protects weeks of work. What to look at, what to record and when to raise a query.
Buying research peptides in the UK: a supplier checklist
A practical checklist for evaluating a UK research peptide supplier before you order: documentation, traceability, company details, and the questions worth asking directly.
Vials vs pre-filled pens: choosing a research format
How lyophilised vials and pre-filled pens differ in stability, preparation, documentation and cost per milligram, and how to pick the right format for a protocol.
How to spot a fake or recycled Certificate of Analysis
The warning signs that a peptide CoA wasn't produced for the batch in front of you, and the five-minute checks that catch most problems.
Lyophilised peptides explained
What freeze-drying does to a peptide, why most research peptides ship as a powder, what you'll see in the vial, and how to store it before and after reconstitution.
How to read a Certificate of Analysis
What a CoA actually certifies, which fields matter most, and how to cross-check one against the batch reference on your label.
RP-HPLC purity testing, explained
A plain-language walkthrough of how reverse-phase HPLC measures peptide purity, and why the number on a CoA means what it says.
Cold-chain handling and storage best practices
General guidance on keeping peptides stable from delivery through to reconstitution — freezer, fridge, and light exposure basics.
GMP-audited manufacturing: what it means for research use
What Good Manufacturing Practice auditing actually covers, and why it's a meaningful signal even for research-only material.
Reconstitution and concentration calculations, explained
The arithmetic behind turning a lyophilized vial into a working solution at a known concentration — and where cost-per-mg comes from.
Batch traceability and verification for research buyers
Why every unit carries a batch reference, what it actually links together, and how to verify one before you rely on it in a protocol.
Third-party testing vs. in-house QC: what's the difference
Why an independent lab's signature on a CoA carries more weight than a manufacturer's own internal results — and when in-house testing is still useful.
Shelf life and expiry dating, explained
How an expiry date actually gets set, why lyophilized and reconstituted forms carry very different windows, and what to do as a date approaches.
Excipients and buffers: what else is in a lyophilized vial
Peptide content isn't the only thing in the vial. A look at the bulking agents and buffer salts that shape how a formulation reconstitutes and behaves.
Molecular weight and sequence labels, explained
What the molecular weight figure on a peptide label actually represents, and how it connects to dosing-volume and mass-spec identity checks.
Bacteriostatic vs. sterile water: choosing a diluent
The practical difference between the two most common reconstitution diluents, and why the choice affects how long a prepared solution stays viable.
Peptide solubility and pH: what affects it
Why some peptides dissolve cleanly in plain water while others need a specific pH, and what that has to do with a sequence's own chemistry.
Solid-phase peptide synthesis, briefly explained
A short primer on SPPS — the resin-bound, cycle-by-cycle method behind almost every research peptide on the market today.
ISO/IEC 17025 lab accreditation: what it signals
The difference between a testing lab that says it's accurate and one that's been independently assessed against a recognised competence standard.
Sterility testing vs. purity testing: what a CoA does and doesn't cover
Purity and sterility are tested for differently and answer different questions — a high purity figure by itself says nothing about one of them.
Documenting a reproducible research protocol: the basics
The record-keeping habits that make a protocol repeatable months later — batch references, preparation details, and storage conditions, logged as you go.