Peptide pens compared: every pre-mixed pen side by side

What a peptide pen is

A pre-mixed peptide pen is a sealed cartridge holding a peptide already in solution, fitted to a dial mechanism that dispenses a measured volume. There is no powder to reconstitute and no diluent to choose, which removes the measuring and transfer steps a lyophilised vial needs. How the dial relates to the contents is set out in how a pre-mixed pen works.

Every pen in the Peptide Global range uses the same 3 ml cartridge. What differs is how much peptide is dissolved in it, which runs from 20 mg to 160 mg. Because the volume is constant, the total mass alone tells you the concentration, and that is the figure that matters when comparing one pen with another. The full range is in the peptide pens UK category.

Every pen, side by side

Every pen is stored at 2–8 °C, protected from light and not frozen, for as long as the cartridge is held. Current prices are on each product page and in the cards below.

Single-compound pens

Seven pens each hold one peptide. Five of them, tesamorelin, ipamorelin, MT2, Semax and Selank, share an identical fill of 20 mg at 6.67 mg/ml, which makes them directly comparable to one another on a per-volume basis. The other two are more concentrated: MOTS-c at 60 mg and GHK-Cu at 100 mg.

They group naturally by what they act on:

• Growth hormone axis: tesamorelin, a GHRH analogue, and ipamorelin, a ghrelin receptor agonist. Different receptors, compared in tesamorelin vs ipamorelin.
• Neuropeptides: Semax and Selank, two heptapeptides with the same stabilising tail on unrelated parents. See Semax vs Selank.
• Melanocortin: Melanotan II, a cyclic heptapeptide, sold as the MT2 pen.
• Mitochondrial-derived: MOTS-c, a 16-residue peptide encoded in mitochondrial DNA.
• Copper tripeptide: GHK-Cu, which is also the main component of both larger blends.

Blend pens

Three pens combine more than one peptide, and they are best read as one family built from the same components:

• Wolverine stack: BPC-157 and TB-500 at 20 mg each.
• Glow: the Wolverine pair plus GHK-Cu at 100 mg.
• KLOW: Glow plus KPV at 20 mg.

Each component sits at the same concentration wherever it appears: GHK-Cu at 33.33 mg/ml and the others at 6.67 mg/ml each. That makes the smaller pens natural controls for the larger ones. The split for every blend is published on its product page, so a per-component concentration is a stated figure rather than a guess. How Glow and KLOW differ is set out in Glow vs KLOW, and when a blend is the right choice at all is covered in blends versus single compounds.

How to choose between them

Three checks narrow it down quickly.

The compound. Start from what the work is about, not from the pen. The compound guides linked above set out what each one is and what is studied with it in vitro.

Single compound or blend. If an observation needs to be attributed to one peptide, a single-compound pen or separate vials are the format. A blend suits work on the combination itself, at a ratio fixed at manufacture.

Pen or vial. A pen removes reconstitution and gives a concentration that is the same every time. A lyophilised vial lets the concentration be chosen and keeps longer before use. Several compounds are available both ways, including GHK-Cu, MOTS-c, ipamorelin, Semax and Selank. The trade-off is set out in pre-mixed pens versus lyophilised vials.

Names are not specifications

Pen names in this market are not standardised. Glow, KLOW and Wolverine are trade names, and the same name from another supplier may mean a different ratio, a different set of components or a different fill volume. Strength claims vary in the same way: a "60 mg" pen elsewhere may be a larger cartridge rather than a more concentrated one. When comparing any two pens, compare the compound list, the total mass and the cartridge volume, and work out the concentration from those. Everything else is a label. What to check before ordering from any supplier is covered in buying research peptides in the UK.

Common questions

What is a pre-mixed peptide pen?

A sealed cartridge holding a peptide already in solution, fitted to a dial mechanism that dispenses a measured volume. There is no powder to reconstitute and no diluent to measure.

How many peptide pens does Peptide Global supply?

Ten: seven single-compound pens (tesamorelin, ipamorelin, MT2, Semax, Selank, MOTS-c and GHK-Cu) and three blends (Wolverine stack, Glow and KLOW). All use a 3 ml cartridge.

Which peptide pen is the most concentrated?

KLOW, at 53.33 mg/ml of total peptide across four components. Among single-compound pens, GHK-Cu is the most concentrated at 33.33 mg/ml.

Are all the pens the same size?

Yes. Every pen uses a 3 ml cartridge. The total mass, from 20 mg to 160 mg, is what changes, and with it the concentration.

Do peptide pens need bacteriostatic water?

No. The compound is already in solution, so there is no reconstitution step. Bacteriostatic water is only needed for lyophilised vials, as covered in bacteriostatic water vs sterile water vs acetic acid.

How should peptide pens be stored?

At 2–8 °C, protected from light and not frozen, for as long as the cartridge is held. Orders leave cold-packed, which covers the journey only, so a pen should go into refrigerated storage on arrival.

Products described in this guide

Supplied for laboratory research use only. UK delivery is £4.95, free on orders over £100, tracked as standard.

Glow Peptide Pen 140mg £140.00 KLOW Peptide Pen 160mg £160.00 Wolverine Stack Pen 40mg (BPC-157 + TB-500) £125.00 GHK-Cu Pen 100mg (Copper Peptide) £90.00 MOTS-c Peptide Pen 60mg £140.00 Tesamorelin Pen 20mg £160.00 Ipamorelin Pen 20mg £110.00 MT2 Pen 20mg (Melanotan II) £70.00 Semax Pen 20mg £110.00 Selank Pen 20mg £110.00

Research use only