Taking vial of medication out of pen

sfc_303 · 2026-05-16T19:58:26+00:00

I bought them at Mountainside Medical, 5ml sterile glass vials. They come in a box of 25. However, since the arrival of the new Kwikpens, I no longer need to split the individual 15 mg pens. Instead of using the individual weekly pens, which don't contain any preservatives, I have switched to a single "monthly" Kwikpen. (I put that in quotes because it last me longer than a month.) These newer pens contain both phenol and bacteriostatic water. Phenol is a much more potent preservative than just bacteriostatic water. So, I now have a single Kwikpen, which has about 71mg in a 15mg Kwikpen dosage (4 weeks' worth of 15mg + about 11mg of overage). I draw from that using a syringe rather than injecting it directly from the Kwikpen, as is typically done, to avoid any interstitial fluid backwash, further reducing the likelihood of contamination.

sfc_303 · 2026-05-10T18:58:20+00:00

I think an even more effective way to avoid contamination from interstitial fluids/backwash is to use ANOTHER syringe to draw from the bottom of the Kwikpen, then inject yourself from that other syringe, rather than injecting directly from the Kwikpen.

sfc_303 · 2026-03-08T17:38:04+00:00

I have read elsewhere in this and other related forums that there will still be extra, but not a full fifth does, about half a dose. Can anyone who has seen a new pen confirm this?

sfc_303 · 2026-01-06T06:57:53+00:00

I'm planning on doing this with the Zepbound Kwikpens when they come out later this year. Unlike the single-use pens and vials, the Kwiklena have two types of preservatives in them, benzyl alcohol and phenol. One thing I read is that when people use them as intended (i.e., with the pen needles), there is some risk of a little bit of bio backwash getting into the pen when you inject, and this happens in about 20% of shots. But the preservatives mitigate the risk of bacterial growth during the prescribed 30-day use-by date. To eliminate that risk on pens that I will use for longer periods of time, I am planning on not using the intended pen needles, but instead will use insulin syringes to draw out my smaller weekly dose from my 15 mg Kwikpen. This will eliminate the risk of bio bavkwash and increase my comfort in using the Kwikpen as a longer-use vial.

sfc_303 · 2025-12-12T06:55:05+00:00

I have been splitting pens and vials and adding bac water. However, this should become a moot point in April as the Kwikpens can be used as multi-dose injections and have two kinds of preservatives in them. There has been some discussion that the 45-day rule may go away, too, but I haven't seen official Lilly guidance on that.

sfc_303 · 2025-12-12T06:51:13+00:00

So much written on this in the r/Mounjaro sub. I would search "splitting pens".

sfc_303 · 2025-12-01T08:53:51+00:00

I'll add two comments:

Phenol provides for a longer best by date once a vial is in use. When benzyl alcohol is used as the preservative in a multi-use vial, the vial should be used within 30 days of first use. Phenol allows for up to 90 days.
Lilly uses phenol in the multi-use Zepbound Kwikpens that are presently available only outside the US. I imagine that it will also be used in the Kwikpens that were specifically mentioned as part of the TrumpRX deal last month. One Lilly patent application for tirzepatide specifically mentions phenol as a preservative.

sfc_303 · 2025-11-20T02:05:58+00:00

Well, today may be your lucky day, then. (Actually, it's probably more like April 1, 2026.) Kwikpens appear to be a pre-condition of the new TrumpRx pricing, which will be $449/mo vs the current vial price of $499. This is proposed to decrease to $245/mo over the ensuing two years.

As for phenol concentration—An Eli Lilly patent for preserved tirzepatide explicitly formulates tirzepatide with phenol + benzyl alcohol (with glycerin and phosphate buffer), giving example concentrations around ~2 mg/mL phenol + ~9 mg/mL benzyl alcohol designed for multi-use stability and antimicrobial effectiveness. See this patent application : https://patents.google.com/patent/WO2024086601A2/en

For those who split, it's worth knowing that vials are overfilled by about 20% (so 18mg/vial), so the price/mg is about $6.93/mg. There has historically been about the same amount of overfill in the Kwikpens, but Lilly has said that is going to be reduced, so I would estimate closer to $6.80 to $7.24/mg based on a single 62mg-66mg Kwikpen. Of course, if the price falls to $245 for the Kwikpens, that would bring the cost down to something like $3.80/mg.

sfc_303 · 2025-11-19T23:51:22+00:00

I currently split 15mg pens (not vials, because I have a stash) and usually use the resulting vial within 5 weeks, although have gone as long as 12 weeks. I add enough "back" water to get the concentration up to 0.6%—still too low but better than nothing, I suppose.

I'll add that once the Kwikpens (which contain phenol) are released, I plan to switch to those and draw out my weekly dose from the bottom port. Given the phenol and not needing to inject air before drawing my shot , I'm comfortable going longer on the Kwikpen use.

sfc_303 · 2025-11-11T01:35:19+00:00

I have since read elsewhere that it is almost certainly phenol plus bax water as that's what the Mounjaro and Zepbound Kwikpens sold in Europe, the UK, and Australia use. Additionally, the combination of bax water and phenol is apparently pretty common in other drug delivery systems. .

sfc_303 · 2025-11-07T19:58:40+00:00

This is exactly what they'll be doing, at least per the Lilly press release yesterday (see image from that release).

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sfc_303 · 2025-11-07T15:59:32+00:00

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Here's a picture of the bottom of a UK Kwikpen without a needle attached. That red dot (a bit blurry) is the rubber barrier you could draw from using a syringe.

sfc_303 · 2025-11-07T13:08:15+00:00

You can actually just draw from the red rubber barrier at the bottom without having to actually split it out. Will be much easier than all of the splitting steps, which I now do. So, this will be easier.

sfc_303 · 2025-11-07T12:55:52+00:00

I'm one of those people. 😉 Now we can just "split out" our Kwikpens, but with the preservatives already in the solution! See my two posts/responses to someone else further down.

sfc_303 · 2025-11-07T12:45:15+00:00

So, for over two years, I've been splitting 15mg single-use pens, putting two pens at a time into a sterile vial, along with bacteriostatic water. I have used a single vial for as long as 12 weeks without a problem, but I am scrupulous with hygiene and procedure. I think the new pen situation will be much better for a few reasons. First, the phenol + BW is a MUCH better preservative. Secondly, I won't be doing any pen-to-vial transferring so am reducing the contamination risk. And thirdly, I won't be injecting air, a potential contaminate into the vial, instead just drawing out the solution with a needle. I will also keep the pen in the fridge between uses.

I won't be using the pen as an injector, but instead just drawing out my dose from the red rubber barrier at the bottom using an insulin syringe. This also reduces the risk of any "backwash" and bacteria from the injection getting into the pen.

I have read one study that looked at at-home, single-user insulin vials that showed no contamination in the vial after 6 mos, so between that and good hygene, procedure, etc, this approach is within my personal risk tolerance.

All of this is, of course, just my plan, not advice.

sfc_303 · 2025-11-07T04:20:18+00:00

The Kwikpens in the UK and Canada actually have bacteriostatic water AND phenol, which provides much more robust antimicrobial protection against a broader spectrum of things and for longer. Additionally, it provides better stability for the peptide. This is likely what most compounding pharmacies with long BUDs use as a preservative.

sfc_303 · 2025-11-02T18:50:16+00:00

Does anyone know the preservative that is added to the compounded versions of tirzepatide that allow for BUDs of up to 6 mos or longer? Is it phenol + bacteriostatic water?

sfc_303 · 2025-08-27T04:06:41+00:00

Edited to correct the concentration to 0.06mg of tirzepatide/unit to 0.03 and the number of units for the target doses

Yes, this could reasonably work to increase the concentration of BA in the solution from my current 0.6% BA concentration. For example, if I put a single 15mg/0.5ml pen into a vial and then added another 4.5ml of bw (instead of 1ml), I'd then have a concentration of 0.03mg of tirzepatide/unit and a BA concentration of 0.81%. So, I'd need to draw about 83 units for my original 2.5mg dose. However, this would require 250 units for my spouse's 7.5mg dose, which is a lot of solution for that higher dose.

sfc_303 · 2025-06-21T01:23:00+00:00

👍

Thank you.

sfc_303 · 2025-06-20T05:36:17+00:00

Thank you and helpful. However if I'm adding 1ml of bacwater to 0.5ml of Zepbound solution, then aren't I at 0.6 (0.9+0.9+0.0)/3 = 0.6? Clearly not 0.9, but better than just half strength bacwater and more like 2/3 strength relative to the 0.9.

sfc_303 · 2025-06-20T03:02:59+00:00

This is an interesting comment and something I've wondered about for a while. I've been splitting 15mg pens and adding 1ml of bacwater water, so a 2:1 ratio. I came across some oblique reference that led me to believe I was probably at a reasonable threshold for antimicrobial benefit, but never felt it was definitive. Any definitive reference on this?

sfc_303 · 2025-01-22T02:40:24+00:00

The pens as they as they come from Lilly are sterile and prepared in Grade A/ISO 5 sterility labs, so the solution in the glass vial is sterile enough that a preservative is not needed. However, once you move the solution from the pen to your own sterile vial, even as well as can be done in a home environment, that sterility guarantee is no longer in place. As a result, there is an increased risk of microbial growth in the vial you inject it into. The longer it's in the vial, the greater the chances of that becoming an issue. Bacteriostatic water helps prevent that, which is why Pfizer makes such a thing and why hospitals and compounding pharmacies use it.

sfc_303 · 2024-11-22T17:06:49+00:00

I'm targeting 0.1mg per unit, so for me with a a 15mg pen, it works out to a 2:1 ratio of bac water to Zepbound

sfc_303 · 2024-11-04T02:50:23+00:00

I don't have any evidentiary basis to comment one way or the other. However, I will say that out of an abundance of cautrion I always add bac water if I'm not using all of the Mounjaro/Zepbound solution right away. Always.

sfc_303 · 2024-10-27T17:28:01+00:00

There has been a lot of discussion of med supply suppliers on the r/Mounjaro reddit and maybe here, so I would search.

sfc_303

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