Peptide pen vs vial

R3vive · Published 6 Nov 2026 · Checked 6 Nov 2026

A peptide pen holds the peptide already in solution, in a sealed 3 ml pen. A peptide vial usually holds freeze-dried powder that has to be measured and mixed first. This guide sets the two formats side by side, so you can decide between a peptide pen or a vial from the facts printed on the pack.

What a peptide pen is

A peptide pen is a sealed, pre-filled pen. Each R3vive pen holds 3 ml and states its total amount in mg on the label; where a pen's catalogue form line reads "Stabilized & pH balanced", it is a stabilised, pH balanced solution. Each box contains 1 pre-filled pen and 4 pen needle tips. If you are asking what is a peptide pen, the short answer is a vial's contents, already in solution, in a pen body.

GLOW 70mg pre-filled peptide pen pack

Our range of pre-filled peptide pens is listed with strength, volume and concentration for each pen.

What a peptide vial is

A peptide vial usually holds lyophilised (freeze-dried) powder. The powder is sealed in the vial and is stored cold, dry and away from light. Before the contents can be used in a laboratory procedure they have to be brought into solution, which means a diluent, a measured volume and your own consumables. Peptide vials in the UK are sold by most web shops, in strengths that vary from shop to shop.

Side by side: form, contents, label, storage, shelf life, price per mg

	Pre-filled pen	Lyophilised vial
Form	Peptide in solution, sealed 3 ml pen	Freeze-dried powder
What you add	Nothing: 4 pen needle tips are in the box	A diluent and your own consumables
Label	Total mg and volume in ml	Usually total mg only
Concentration known before opening	Yes: total mg divided by 3 ml	No: it depends on the volume you add
Storage	R3vive's catalogue line: store at 2–8°C, refrigerate on arrival	Set by the vial's supplier; R3vive's catalogue line for its powders is "Store at 2–8°C". Keeping powder sealed, dry and away from light is general handling advice
Shelf life	Set by the supplier's stability data; we state no figure here	Set by the supplier's stability data; we state no figure here
Price per mg	See our UK pen price per mg table	Varies by shop and by vial size

Concentration: why a pen states it and a vial does not

Concentration is the amount of peptide in each millilitre. A pen is filled to a fixed volume, so its concentration follows from its label: total mg divided by 3 ml. GLOW 70mg in 3 ml is 23.3 mg/ml. GHK-Cu 100mg in 3 ml is 33.3 mg/ml. NAD+ 1000mg in 3 ml is 333.3 mg/ml.

A vial's concentration is set by whoever adds the diluent, so the same vial can give a different concentration each time. Our peptide concentration calculator works out mg per ml from total mg and volume, and has a preset for each pen on our Peptide Pens page.

Storage for each format

R3vive's catalogue gives "Store at 2–8°C" for every product, pens and powders alike. Refrigerate a pen on arrival, upright and away from light; keep powder sealed and dry. Other suppliers set their own storage line, so read the one on the pack you hold.

Which format UK shops sell

Of six leading UK peptide shops we inspected on 28 October 2026, five sold vials only. Pre-filled pens are the less common format, which is why a pen shop has to state clearly what is in each pen. Many vial products are sold in 5 mg and 10 mg sizes; a 3 ml pen is a different unit, so compare per mg rather than per pack.