Yes, it is possible to draw up 1/1,000,000 of the vial into a syringe.
To find out how much of the vial should be drawn up, you can divide the amount of the drug ordered (20 units) by the total amount of the drug in the vial (20,000,000 units). This gives you the proportion of the vial that should be drawn up:
20 units / 20,000,000 units = 0.00000001 (or 1/1,000,000)
Therefore, you can draw up 1/1,000,000 of the vial into a syringe to get the correct dosage of 20 units.
However, it's important to note that you need to be very careful and precise when measuring these tiny doses as even small errors can have serious consequences.
It is recommended to always double-check the calculations, and the equipment used should be calibrated and verified before use.