How to Use Your Reusable (Refillable) Peptide Pen (V2, V3, V4 and V5) — Research Equipment Guide

A reusable, refillable peptide pen is a precision dial-and-click delivery device used in laboratory research to dispense reconstituted peptide solutions in accurate, repeatable volumes. This guide covers setup, priming, and maintenance for the Reusable Peptide Pen and Peptide Pen Kit. Written for laboratory and research purposes only.

Read the video transcript

Here’s how to use your Optimised Lifestyle peptide pen, step by step. You’ll need your pen, a filled 3 millilitre sterile cartridge, a fresh single-use pen tip, alcohol wipes and a sharps bin. First, unscrew the pen and slide in the cartridge, then screw it back together. Next, thread a compatible pen tip onto the threaded end. Use a fresh tip every time. Now prime the pen. Dial to the smallest increment, point the pen upward and press the plunger until a drop appears at the tip. You only need to prime when you load a new cartridge. Turn the dose dial to the volume you need. Each line on the dial is 1 IU, and the pen dials up to 60. Press the plunger fully and hold briefly before withdrawing. When you’re done, remove the tip and dispose of it safely in a sharps bin. Never reuse a tip: a fresh one prevents contamination and dulling. Wipe the pen body with alcohol between uses, but never submerge it. Store your loaded pen refrigerated, following your solution’s storage guidelines, and label your cartridges clearly if you run more than one. The common mistakes are skipping priming, reusing tips, storing the pen incorrectly and mixing up cartridges. Avoid those, and the pen does the rest. Always follow the guidance of your healthcare professional.

Which Pens Does This Guide Cover?

This guide works for any reusable (refillable) dial-and-click peptide pen, including V2, V3, V4 and V5 pens — every version works the same way. The steps are identical: load a 3ml cartridge, fit a pen tip, prime, set the dial and press the plunger. We demonstrate them on the Optimised Lifestyle V3 pen; the newer V5 pen follows the same steps with two differences covered below.

Using the V5: What’s Different

The V5 differs from the V3 in two ways that matter in use: its dial is marked to 80 IU rather than 60 (each line is still 1 IU), and its needle retracts into the pen, staying hidden while the pen is in use — so don’t be surprised not to see the tip exposed once fitted. Loading, priming and dispensing are otherwise identical, and it takes the same 3ml cartridges and pen tips. The pen versions guide has the full V3 vs V5 comparison.

What Is a Reusable (Refillable) Peptide Pen?

A peptide pen is a reusable, refillable, dial-and-click device built around a replaceable 3ml sterile cartridge. Rather than drawing a solution by hand with a syringe for every use, the dial mechanism delivers a fixed, repeatable volume per line — each line on the dial equals 1 IU, up to a maximum of 60 IU per setting on the V3 and 80 IU on the V5 — useful anywhere dosing consistency matters across a research series. The pen body is reusable, and you refill it by loading a fresh cartridge; the cartridge and tip are changed per fill. Need to fill a cartridge first? See how to fill a peptide pen cartridge.

Pen vs Syringe: When to Use Each

A syringe is drawn to volume by hand for every single use, which gives full flexibility over volume but relies on reading the barrel accurately each time. A pen uses a fixed-increment dial against a pre-loaded cartridge, trading some flexibility for speed and consistency — useful when the same volume is dispensed repeatedly across a research series. Many researchers keep both: a syringe for reconstitution and ad-hoc volumes, a pen for repeat, fixed-volume work.

What You’ll Need

• A pen body, or the full Peptide Pen Kit if starting from scratch
• A filled 3ml sterile cartridge containing your reconstituted solution — see our reconstitution guide
• Bacteriostatic water for reconstitution — from a laboratory supplier
• A compatible pen tip
• Alcohol wipes
• A sharps disposal container

Setting Up Your Pen

1. Load the Cartridge

Unscrew the pen body and insert the filled 3ml sterile cartridge.

2. Attach a Pen Tip

Thread a compatible pen needle (also called a pen tip) onto the pen’s threaded end — we stock 31G x 6mm needles, individually sealed and sterile. Not sure which size? See the needle size guide.

3. Prime the Pen

Dial to the smallest increment and press the plunger with the pen pointing upward until a drop appears at the tip — this confirms any air introduced during loading has been expelled.

4. Set the Dial

Turn the dose dial to the required volume. Each line on the dial equals 1 IU, and the pen dials up to a maximum of 60 IU on the V3 (80 IU on the V5).

5. Dispense

Press the plunger fully and hold briefly before withdrawing.

Cleaning & Storage

Store your reconstituted solution according to our peptide storage guide — most reconstituted solutions are kept refrigerated. Wipe the pen body with an alcohol wipe between uses; do not submerge it. Replace the pen tip after each use to avoid contamination and a dulled tip. Running low on cartridges? Restock 3ml sterile cartridges here.

Common Mistakes

• Skipping the priming step — the first dispense after loading a new cartridge will be inaccurate if air hasn’t been expelled first.
• Reusing a pen tip — increases contamination risk and dulls the tip with each use.
• Storing a loaded pen at room temperature — follow the same storage rules as your reconstituted solution.
• Mixing up cartridges between solutions — label each loaded cartridge clearly if running more than one research line at a time.

Frequently Asked Questions

How many units are in one click of a peptide pen?

Each line on the dial equals 1 IU. The dial maximum is 60 IU on the V3 and 80 IU on the V5.

Is a peptide pen reusable or refillable?

Both. The pen body is reusable, and you refill it by loading a fresh, filled 3ml cartridge. Pen tips are single use.

Do I need to prime a new peptide pen every time?

Priming is needed whenever a new cartridge is loaded, to expel any air introduced during loading. It isn’t required before every single dispense from an already-primed cartridge.

Can a peptide pen tip be reused?

No — pen tips are intended for single use. Reusing a tip increases contamination risk and can dull the tip, affecting consistency.

What’s the difference between a peptide pen and a syringe?

A syringe is drawn to volume by hand for each use, offering full flexibility. A pen uses a dial-and-click mechanism against a pre-loaded cartridge, giving a more repeatable, consistent volume per dispense without measuring by hand each time.

How do I know my peptide pen is properly primed?

A small, visible drop should appear at the tip when the plunger is pressed with the pen pointing upward. If no drop appears, repeat the priming step before dispensing.

How do I use a V3 peptide pen?

Load a filled 3ml cartridge, fit a fresh pen tip, prime until a drop appears at the tip, dial the volume (each line is 1 IU) and press the plunger fully, holding briefly before withdrawing. The full steps are above.

Does this guide work for V2, V4 and V5 peptide pens?

Yes. V2, V3, V4 and V5 peptide pens all work the same way, so the same steps apply: load the cartridge, attach a tip, prime, set the dial and press the plunger. The V5’s two differences — an 80 IU dial and a retracting needle that stays hidden in use — don’t change the steps.

Further Reading

• Reusable Peptide Pen (V3)
• Reusable Peptide Pen V5 — pre-order
• Peptide Pen Kit
• 3ml Sterile Glass Cartridge
• How to Safely Reconstitute Peptides
• Peptide Storage UK — Best Practices

More from Optimised Lifestyle

Alongside research equipment, Optimised Lifestyle offers private blood testing in the UK — thirteen panels analysed by a CQC-registered, UKAS-accredited laboratory, from £45, with results reported against standard reference ranges. See the range. For over-18s in the UK; not a diagnosis and not a substitute for seeing a doctor.