NurseKim_ATL said:Dead space is the answer to the missing dose.
I am going to disagree with reconstituting low as a general rule. More diluent, more punctures, more in-use days at room temperature, and the stability trade-off is real. Precision is not the only variable being optimised.
marco_milano said:I reconstituted a 10mg vial with 2ml of bacteriostatic water and I want someone to check my unit arithmetic before I draw anything, because I keep…
Comparison of compounded dosing arithmetic delivery formats I've tried:
| Format | Pros | Cons |
|---|---|---|
| Lyophilized vial | Longest shelf life, lowest cost | Requires reconstitution |
| Pre-mixed vial | Ready to draw up | Shorter shelf life (28-45 days) |
| Pre-filled syringes | Most convenient | Higher cost, shorter shelf life |
| Sublingual drops | No needles | Lower bioavailability, less data |
I use lyophilized vials for cost and stability. The reconstitution takes 30 seconds once you've done it a few times.
Dr.PainCLE said:I am going to disagree with reconstituting low as a general rule.
Regarding dosing arithmetic multi-dose vial contamination prevention: after reconstituting, I wipe the vial stopper with a fresh alcohol swab before EVERY single draw. I also never touch the stopper with my fingers and use a new needle for each draw.
Even with bacteriostatic water preservative, contamination is cumulative. One sloppy draw can introduce bacteria that multiply over days. Aseptic technique isn't optional — it's essential for injectable medications.
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Browse GL BiochemA narrower follow-up, since the general answer is now clear:
How much material I am losing to dead space, and whether that explains why a 10mg vial gives me nine usable draws rather than ten?
Closing the loop on my own question.
Follow-up: it was dead space. Switching to a low-dead-space fixed-needle syringe gave me the tenth dose back.