Does vial size make a difference?

Secretdaya

Secretdaya

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From what I gather, many GLP1s are sold in 3ml vials by different suppliers. I bought sterile empty vials on my own, and when they showed up I was taken aback by how small they were. I guess I hadn't given it much thought before — I just went with quick assumptions drawn from the vials I know best (the ones from well-known compounding pharmacies). I was mistaken. Compared to those, the vials I used to get from a compounding pharmacy are enormous.

But that's beside the point.

What I'm wondering is whether it matters at all if I mix into a 3ml vial versus a 5ml, 10ml, or even larger one. Assuming the concentration and dose are right, and as long as the needle is the right size to draw the solution, is there any drawback to a larger vial? Could the additional "air space" affect the peptide or the sterility of what's inside?

Anyone have thoughts on this?
 
Glutathione typically comes in much bigger vials, even though plenty of people mix it with only a modest volume of BAC. Nobody seems to mind.

When vials are that large, Gemini points out that oxidation becomes more likely—though in most cases that wouldn't really be an issue:

Tirzepatide and Retatrutide contain amino acids (like Methionine) that are prone to oxidation.... If you're using the vial within 2-3 weeks, you'll never notice. But if you're stretching a vial over 6-8 weeks, that extra air in a 10ml vial might lead to a slight, silent drop in potency toward the end.

Click to expand...
Click to expand...
 
For just about any use case, 3mL works. When dealing with peptides, looking at concentration isn't the right approach. Instead, decide reconstitution by the volume you'd like per injection, plus the number of mg of peptide you're after. There's a reverse calculator linked in my signature.

Back when I started compounded tirz @2.5mg/week, the vials they shipped were 1mL. Extremely small.

On another note, what's the reason for reconstituting into empty vials in the first place? If you've never reconstituted peptides before, you might have thought (like I once did) that this step is required. It isn't. Nearly always, you pierce the self-sealing stopper of the bac water with a hypodermic needle to pull out the liquid, then push it through the self-sealing stopper of the lyophilized peptide vial. That's it.

I avoid transferring into empty vials altogether, since I'm skeptical of suppliers' sterility claims, and doing a proper job of sterilizing at home isn't realistic
 
I don't know if this is actually a drawback, or whether it even matters, but I've seen that condensation builds up more when the vial is bigger.

Whether that could throw off your concentration, I'm honestly not sure.

Whenever I pull it from the fridge, I just swirl and roll it gently, then let it sit for a few minutes at minimum before pinning.
 
indolent said:

For just about any use case, 3mL works. When dealing with peptides, looking at concentration isn't the right approach. Instead, decide reconstitution by the volume you'd like per injection, plus the number of mg of peptide you're after. There's a reverse calculator linked in my signature.

Back when I started compounded tirz @2.5mg/week, the vials they shipped were 1mL. Extremely small.

On another note, what's the reason for reconstituting into empty vials in the first place? If you've never reconstituted peptides before, you might have thought (like I once did) that this step is required. It isn't. Nearly always, you pierce the self-sealing stopper of the bac water with a hypodermic needle to pull out the liquid, then push it through the self-sealing stopper of the lyophilized peptide vial. That's it.

I avoid transferring into empty vials altogether, since I'm skeptical of suppliers' sterility claims, and doing a proper job of sterilizing at home isn't realistic
Click to expand...

Those things were adorable — I had no idea a vial could be.

indolent said:

For just about any use case, 3mL works. When dealing with peptides, looking at concentration isn't the right approach. Instead, decide reconstitution by the volume you'd like per injection, plus the number of mg of peptide you're after. There's a reverse calculator linked in my signature.

Back when I started compounded tirz @2.5mg/week, the vials they shipped were 1mL. Extremely small.

On another note, what's the reason for reconstituting into empty vials in the first place? If you've never reconstituted peptides before, you might have thought (like I once did) that this step is required. It isn't. Nearly always, you pierce the self-sealing stopper of the bac water with a hypodermic needle to pull out the liquid, then push it through the self-sealing stopper of the lyophilized peptide vial. That's it.

I avoid transferring into empty vials altogether, since I'm skeptical of suppliers' sterility claims, and doing a proper job of sterilizing at home isn't realistic
Click to expand...
Filtering?
 
The only real drawback I can see is that extracting the final bits of liquid tends to be trickier when a vial has a bigger stopper.

Most of the time, though, going with a larger vial just makes more sense. Take 3mL vials holding 60mg of reta as an example: at a 4mg dose, you'd get 15 doses out of each one. If you're aiming for .25mL per dose, that works out to 3.75mL of fluid needed, or 3mL if you use .2mL per dose. In either case, a 3mL vial can technically hold slightly more than 3mL, but going past roughly 2.5mL is generally not ideal because there's too little airspace left. For my own part, I'd rather reconstitute with 4.5mL of fluid inside a 5mL vial to get .3mL doses — and by the way, using more water translates to more accurate dosing.
 
Calm Logic said:

indolent said:

For just about any use case, 3mL works. When dealing with peptides, looking at concentration isn't the right approach. Instead, decide reconstitution by the volume you'd like per injection, plus the number of mg of peptide you're after. There's a reverse calculator linked in my signature.

Back when I started compounded tirz @2.5mg/week, the vials they shipped were 1mL. Extremely small.

On another note, what's the reason for reconstituting into empty vials in the first place? If you've never reconstituted peptides before, you might have thought (like I once did) that this step is required. It isn't. Nearly always, you pierce the self-sealing stopper of the bac water with a hypodermic needle to pull out the liquid, then push it through the self-sealing stopper of the lyophilized peptide vial. That's it.

I avoid transferring into empty vials altogether, since I'm skeptical of suppliers' sterility claims, and doing a proper job of sterilizing at home isn't realistic
Click to expand...

Those things were adorable — I had no idea a vial could be.

indolent said:

For just about any use case, 3mL works. When dealing with peptides, looking at concentration isn't the right approach. Instead, decide reconstitution by the volume you'd like per injection, plus the number of mg of peptide you're after. There's a reverse calculator linked in my signature.

Back when I started compounded tirz @2.5mg/week, the vials they shipped were 1mL. Extremely small.

On another note, what's the reason for reconstituting into empty vials in the first place? If you've never reconstituted peptides before, you might have thought (like I once did) that this step is required. It isn't. Nearly always, you pierce the self-sealing stopper of the bac water with a hypodermic needle to pull out the liquid, then push it through the self-sealing stopper of the lyophilized peptide vial. That's it.

I avoid transferring into empty vials altogether, since I'm skeptical of suppliers' sterility claims, and doing a proper job of sterilizing at home isn't realistic
Click to expand...
Filtering?
Click to expand...
Yes.

ZippityDooDah said:

The only real drawback I can see is that extracting the final bits of liquid tends to be trickier when a vial has a bigger stopper.

Most of the time, though, going with a larger vial just makes more sense. Take 3mL vials holding 60mg of reta as an example: at a 4mg dose, you'd get 15 doses out of each one. If you're aiming for .25mL per dose, that works out to 3.75mL of fluid needed, or 3mL if you use .2mL per dose. In either case, a 3mL vial can technically hold slightly more than 3mL, but going past roughly 2.5mL is generally not ideal because there's too little airspace left. For my own part, I'd rather reconstitute with 4.5mL of fluid inside a 5mL vial to get .3mL doses — and by the way, using more water translates to more accurate dosing.
Click to expand...
Thanks, that makes sense. This is one of the cases I had in mind — you need more liquid volume.

At the same time, I'm wondering about my own handiness when working with these smaller vials. It comes down to what size I'm comfortable handling. From what I gather, I can pick whichever I like, as long as it's reasonable.
 
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