Will following the advice from the old Reddit comment below solve my pressurization problem? u/OsmiumOG wrote: "your first stab should be with a sole leur needle with no barrel, or pull the plunger out completely, then stab the needle. it'll pull in the air it needs to reach the equilibrium in air pressure without needing to do any kind of special formula. it'll pull what it needs, won't pull any extra. then you'll be at a net0 vacuum inside the vial." https://www.reddit.com/r/Peptides/comments/vwglww/comment/ifqjqqc/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

I tried pen splitting by emptying Zepbound pens into a vial. I added 3 Zepbound pens containing 5 mg of tirzepatide each to a 3 mL vial. Each pen contained .5 mL liquid. I then added 1.5 mL bacteriostatic water. (I split the pens in order to permit twice weekly dosing & to permit dose increases in smaller increments than permitted by the pens. I added the bacteriostatic water since the Zepbound do not contain a preservative.) I gently turned the vial while horizontal to mix the solution. Then I attempt to withdraw liquid as I did when using compounded tirzepatide. I injected an amount of air equivalent to what I intended to withdraw. However, the vial started fighting me over the liquid and I couldn't withdraw the precise amount I needed. I then used a large syringe and added a bunch of air. Then I had a pressurization problem where the vial started forcing the liquid into the syringe. I was unable to fill my syringe with an amount close enough to what I had intended to injected. I gave up for the night and used some of my remaining compounded tirzepatide. Will the solution described above by u/OsmiumOG work? Thanks for your help.