kate.chem 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…
For anyone reconstituting dosing arithmetic peptides: the water-to-powder ratio determines your concentration. Here's my reference:
| Vial Size | BAC Water | Concentration | 0.25mg Dose |
|---|---|---|---|
| 5mg | 2mL | 2.5mg/mL | 10 units |
| 5mg | 2.5mL | 2mg/mL | 12.5 units |
| 10mg | 2mL | 5mg/mL | 5 units |
| 10mg | 3mL | 3.33mg/mL | 7.5 units |
More water = easier to measure small doses but vial runs out faster. Find the balance that works for your dose.
One thing that is still open after Dr.EndoIndy’s answer:
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?
quinn_sf said:For anyone reconstituting dosing arithmetic peptides: the water-to-powder ratio determines your concentration.
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 BiochemClosing the loop on my own question.
Resolved. I wrote mg, ml and mg/ml on the vial in marker and did the division in that order, and the two of us now get the same number every time.
Dr.GutHealth said:Regarding dosing arithmetic multi-dose vial contamination prevention: after reconstituting, I wipe the vial stopper with a fresh alcohol swab before…
Agreeing with Dr.GutHealth, and the qualification matters more than the agreement. The arithmetic is right and one caveat matters: a U-40 syringe changes the markings, not the volumes. If someone hands you U-40 and you read it as U-100 you will be 2.5 times out, and that error has a direction — it is always an overdose.
If somebody has the primary source to hand I would rather cite it than paraphrase it.