The 30 mg vial
Seven diluent volumes and seven amounts, all worked out for one vial mass. In 2 mL this vial is at most 15.000 mg/mL, which puts 1500.0 mcg in each tenth of a millilitre.
Educational arithmetic only. Not medical advice and not a dosing protocol.
| Diluent | Strength, mg/mL | In 0.1 mL, mcg |
|---|---|---|
| 0.5 mL | 60.000 | 6000.0 |
| 1 mL | 30.000 | 3000.0 |
| 1.5 mL | 20.000 | 2000.0 |
| 2 mL | 15.000 | 1500.0 |
| 2.5 mL | 12.000 | 1200.0 |
| 3 mL | 10.000 | 1000.0 |
| 5 mL | 6.000 | 600.0 |
What is particular to a vial this size
The largest vial here, and the one where the ceiling on the strength matters most. Thirty milligrams of solid displaces more volume than one milligram does, so the gap between mass-over-diluent and the true strength is at its widest on this page. Every figure in the first table below is an upper bound, and on this vial that bound is doing more work than on any other.
| Amount per draw | Whole draws | Exact ratio | Left over |
|---|---|---|---|
| 1 mg | 30 | 30.00 | nothing |
| 1.5 mg | 20 | 20.00 | nothing |
| 2 mg | 15 | 15.00 | nothing |
| 3 mg | 10 | 10.00 | nothing |
| 5 mg | 6 | 6.00 | nothing |
| 6 mg | 5 | 5.00 | nothing |
| 10 mg | 3 | 3.00 | nothing |
Reading the two tables together
The first table fixes the strength and therefore the volume of every draw. The second fixes the number of draws and ignores the volume entirely, because how many times an amount divides into a vial has nothing to do with how much liquid the vial was mixed with. A 30 mg vial holds the same number of 2000 mcg draws whether it was mixed in half a millilitre or five.
What the diluent volume changes is whether each of those draws is measurable. That is the trade-off the two tables are for: pick the row in the second that gives the draw count you are working with, then pick the row in the first that makes that draw a readable length on the barrel you have.
Why every strength here is a ceiling
Strength is mass divided by the volume of the finished solution, and the finished solution is the diluent plus the room the solid itself takes up. With that displacement unmeasured, dividing by the diluent gives the highest the strength can be rather than the strength it is. Every figure in the first table is that ceiling, which is why it is labelled one.
Measuring the finished volume removes the question. The vial strength tool has a field for it and drops the ceiling label when it is filled in.
Next to this on the bench
- The draws-per-vial tool
Any vial, any amount, with the remainder.
- The other seven vial strengths
Same two tables, different mass at the top.
- Displacement and the ceiling
Why the first table says "at most".