TrialTracker_MD 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.
Dr.NateNeph 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…
Compounding pharmacy dose accuracy check for dosing arithmetic: I always verify my first dose from a new vial by weighing it on a milligram scale. Draw up your dose, weigh the syringe, subtract empty syringe weight, compare to expected water weight at that volume.
For a 10-unit dose (0.1mL): expected weight ~100mg of water. If it's significantly off, your syringe may be inaccurate. Cheap insulin syringes can have ±5% volume accuracy. Spring for quality brands like BD or Terumo.
LarryQC_SD said:I am going to disagree with reconstituting low as a general rule.
Peptide calculator app recommendation for dosing arithmetic: I use ReconCalc to calculate reconstitution volumes and injection doses. Eliminates math errors completely.
Input: vial size (mg), desired concentration (mg/mL), prescribed dose (mg)
Output: BAC water volume (mL), injection volume (units on insulin syringe)
A math error with injectable medication can mean underdosing or overdosing. Use a calculator every time until the math becomes second nature.
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.
Follow-up: it was dead space. Switching to a low-dead-space fixed-needle syringe gave me the tenth dose back.