Reta injection probs?

the pressure buildup in sealed vials is the one that catches people by surprise - if you inject air in to draw without releasing the vacuum first, or if the vial has been warming and you inject cool liquid against pressure, the stopper can push back hard. scoring the crimp ring partially rather than removing it completely and using a vent needle or slow equalization technique prevents the blowback

drawing cold from the fridge is fine for most compounds - the viscosity is slightly higher but not enough to meaningfully slow the fill on a 30g+ needle. the convenience of not waiting for warm-up is worth it for most people, and there's no reconstitution stability benefit to a few minutes at room temp. the only case where warming matters is when sting on injection is a persistent problem