Available now
Retatrutide
40 mg£200£5.00/mg
Pre-filled pens
Peptide pens, supplied in the UK
Filled and sealed in Switzerland, dispatched from the UK, and analysed batch by batch by an independent laboratory whose report you can open on their server rather than ours.
What the format removes
A pre-filled pen is not a different compound. It is the same material supplied in a form that takes four steps out of the process, and with them the places those steps go wrong.
Reconstitution
A vial of lyophilised powder has to be brought back into solution before anything can be measured. A pen arrives as a solution.
Bacteriostatic water
The diluent is a separate purchase, with its own shelf life and its own storage conditions. A pen needs none.
Measuring and maths
Concentration depends on how much diluent went in, so every figure downstream depends on that one step being right.
Transfer
Every movement between containers is an opportunity for contamination and for loss.
None of that makes a pen the right format for every purpose. A lyophilised vial holds its stability longer and lets the concentration be chosen rather than inherited. The two formats, side by side.
What is in the box
A pen on its own is not a kit. Everything needed to handle it ships in the same carton, so nothing has to be sourced separately and nothing arrives in the wrong size.
The pen
Pre-filled and factory-sealed, with the batch number printed on the carton. Most are a single multi-dose pen; Glow is supplied across two. Nothing to reconstitute and no diluent to buy.
Needles
Sterile single-use needles, supplied with the pen — 5 mm on most of the range. No separate purchase and nothing to size up.
Swabs
Pre-injection swabs, 70% isopropanol.
The report
Every batch carries its own independent analysis. The number on the carton is the number on the report.
On arrival: refrigerate at 2–8°C, keep it in the original carton away from light, and do not freeze it. What happens when a pen has spent a day warm is a fair question and we answer it in my pen arrived warm.
The pens
4 available now, 5 in production. Every one pre-filled, factory-sealed, and carrying its own batch number and its own report.
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Tirzepatide
40 mg£160£4.00/mg
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BPC‑157 + TB‑500
40 mg£140
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Tesamorelin
32 mg£210£6.56/mgat launchNotify me
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CJC‑1295 DAC
10 mg£110£11.00/mgat launchNotify me
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In production
Showing 9 of 9 · Tracked UK delivery, free at £250 · Research use only
Don’t trust us. Check us.
Every batch is analysed by Janoshik Analytical, an independent laboratory in the Czech Republic with no relationship to us. Each report carries a verification key, and the key opens the report on Janoshik’s own site. If their page disagrees with ours, believe theirs.
- The compound — on the GLP-1 pens, identified blind, without us naming it first
- The measured content, in mg per ml
- The measured purity, where the pen holds a single compound
- The batch number, matching the carton in your hand
Read before you order
Handling & storage
Pre-filled pens vs lyophilised vials: what the format changes
Freeze-dried powder in a vial, or solution in a sealed pen. The two formats research peptides are supplied in, what each asks of you, and where each one can go wrong.
8 September 2026 · 4 min
ReadTesting & quality
What a Janoshik report proves — and the four things it doesn't
The lab every UK vendor cites. What its reports actually measure, how to verify one yourself in thirty seconds, why two labs give two numbers for one batch, and the four things no purity report can tell you.
8 September 2026 · 5 min
ReadHandling & storage
Peptide storage: 2–8°C, light and freezing
Why 2–8°C, what heat and light do to a peptide, why freezing a solution is worse than a warm afternoon, and how long a pen lasts once it is in use.
8 September 2026 · 4 min
ReadQuestions
What is a pre-filled peptide pen?
A multi-dose pen containing the compound already in solution, filled and sealed at the manufacturing site. It is supplied ready to handle, with no reconstitution step and no separate diluent.
Are peptide pens better than vials?
They are a different format with different trade-offs rather than a straightforwardly better one. A pen removes reconstitution, measuring and transfer. A vial of lyophilised powder is more stable over long periods and lets a researcher choose their own concentration. We set the two out side by side in the journal.
Where are these pens made?
Switzerland. One facility, one process, every batch. Nothing is blended from multiple sources or re-labelled in transit. Orders are dispatched from the UK.
How do I know what is actually in the pen?
Every batch is analysed by Janoshik Analytical, an independent laboratory in the Czech Republic, and every report carries a verification key. The key opens the report on Janoshik's own site rather than ours, so the document you read is the one the laboratory issued.
Do peptide pens need refrigerating?
Storage conditions are printed on the carton and set out in full in the journal. A pen in transit and a pen in storage are two different questions and we answer both there.
What needles come with a peptide pen?
Sterile single-use 5 mm needles are supplied in the carton with the pen, along with 70% isopropanol swabs. There is nothing else to buy and no needle length to choose.
Do peptide pens come as a kit?
Ours do. The pen or pens, their needles, their swabs and the batch analysis, in one carton — Glow is supplied across two pens, the rest as a single pen. A pen sold without the rest is not a complete kit, and the missing parts are usually the ones that are awkward to source separately.
Do you deliver outside the UK?
We dispatch from the UK and also ship to the EU and EEA. International orders carry a flat charge per item and the buyer accepts import responsibility. The shipping policy sets out the terms in full.
Supplied for laboratory research use only. Not for human or veterinary use.