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3ml Pen Injector Pre-Purged Vial: Thoughts?

9 replies7 peopleMar 7, 2026☆ Follow
Summary

Are pre-purged 3ml pen cartridges worth using for reconstituted peptides or do they introduce contamination risks compared to standard transfer methods?

Users describe moving from insulin syringes to pen cartridges for dosing precision and comfort, noting that transfers require multiple needles and some waste. Pre-purged options reduce venting steps but raise concerns about air exposure in the cartridge before filling. Most prefer venting and filling freshly wiped cartridges themselves while filtering, and reuse needles only within the same peptide session. Needle gauge advice centers on avoiding coring of stoppers.

What this discussion establishesWhere people disagree

Whether the sterilization of pre-purged cartridges offsets the risk of filling into an air-exposed space versus briefly exposed transfer needles

Still open

Actual contamination rates or sterility data for pre-purged versus freshly vented cartridges

Nothing here is advice.

9 replies · 7 people
NorthLantern91archiveopening postMar 7

At the start of using peptides I relied on standard insulin syringes. After losing any fear of self-injection I moved to pens because they gave more accurate dosing and no pain, so I now move all reconstituted peptides into 3ml pen cartridges. The transfer needs several needles and wastes some product when done safely. I found these steam-sterilized pre-purged vials and wonder whether the long open space inside could allow contamination.

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SteadyQuill55archiveMar 7

I tried filling after pre-purging and it saved the venting step, but I stopped and went back to venting the cartridge myself. Since I already filter and work hard to stay sterile it feels risky to fill into a cartridge that has sat open to air, so I avoid that approach now.

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KeenFenwick81archiveMar 7

I just ordered some v4 pens and was thinking through the steps. It does use up a lot of supplies: one luer lock for reconstitution, a filter, another luer lock and syringe for venting and transfer, plus a pen needle to purge air. When loading two new cartridges can any of those items be reused safely?

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NorthLantern91archiveMar 7
↳ replying to @SteadyQuill55

I share the same view. I always filter after reconstituting and stay very strict on cleanliness. My only question about skipping the pre-purged cartridges is whether the sterilization makes them any riskier than using several needles that have each been exposed to air briefly during venting and transfer with regular vials.

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SteadyQuill55archiveMar 8
↳ replying to @KeenFenwick81

I reuse the same vent needle when doing multiple cartridges of the same peptide in one session. Everything stays within sterile cartridges that were wiped with alcohol. For a 12 ml batch that needs four cartridges I use one vent needle across all of them and a single 13mm filter for the whole volume.

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PatientSignal60archiveMar 8

I'm about to order needles and syringes for making up cartridges. Which sizes do you use?

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NorthLantern91archiveMar 8
↳ replying to @PatientSignal60

For regular insulin needles I use 1 ml 31 gauge 5/16 inch. For the 3 ml cartridges any size works for venting; I have used 20 gauge for that. To pull the solution and move it I use 18 gauge. Remember the 13 mm filters as well.

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BlueSignal49archiveMar 8
↳ replying to @PatientSignal60

I started with a kit and was satisfied, so now I just purchase the items in larger quantities from a general retailer since I know what is required. It also includes some bacteriostatic water.

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ClearWillow59archiveApr 7
↳ replying to @NorthLantern91

A study found that gauges below 22 can cause coring, pulling a piece of the rubber stopper into the solution. I stay at 25 gauge or higher and insert at an angle to reduce the chance.

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BlueTimber78archiveApr 7
↳ replying to @ClearWillow59

I read about vials breaking into fragments with core issues turning up as a risk we can steer clear of.

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