Dr.PeteFamMed said:Do it in two steps and it stops being confusing.
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.
hannah_MT 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.
sarah.morrison said:I am going to disagree with reconstituting low as a general rule.
Quick syringe math for dosing arithmetic dosing: if your vial is reconstituted at 5mg/2mL, that's 2.5mg/mL. For a 0.25mg dose you need 0.1mL = 10 units on an insulin syringe.
I keep a chart on my fridge:
- 0.25mg = 10 units
- 0.5mg = 20 units
- 1.0mg = 40 units
- 1.25mg = 50 units
Always double-check your concentration before drawing up!
Sigma-Aldrich — Research-Grade Standards
Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.
Shop Reference StandardsA narrower follow-up, since the general answer is now clear:
How to check the arithmetic without trusting a website calculator, since three calculators gave me three answers?
Closing the loop on my own question.
My error was treating units as a mass. Once I wrote mg/ml on the vial in marker and worked in millilitres first, the two of us got the same answer.