Vial pushing air into syringe

@debbie58 wrote:

I was reconstituting a peptide 30 mg to two ML bac water. When injecting the bac instead of pulling the water in there was much resistance, and if I let go of the plunger air bubbles came up in the s...

Typically, no. if I am understanding correctly. Most unreconstituted peptides should be under vacuum pressure and naturally draw the reconstitution fluid in unless you stabilized the air pressure beforehand. There is exceptions for things like BAC water or non-peptide vials.