Insulin syringe units to mg conversion — the complete reference thread
Posting this as an important update for the dosing & protocols community. Please read carefully as this may affect your current plans.
I will keep this thread updated as new information becomes available. If you have additional information or corrections, please post below and I will incorporate confirmed updates into this OP.
Key points:
- This information is current as of the date posted
- Circumstances may change — always verify independently
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PharmD_Rodriguez said:Insulin syringe units to mg conversion — the complete reference thread Posting this as an important update for the dosing & protocols community.
That is correct as far as it goes, and here is where it stops going. 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.
PharmD_Rodriguez said:Insulin syringe units to mg conversion — the complete reference thread Posting this as an important update for the dosing & protocols community.
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.
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Browse GL BiochemTaking the question as asked, rather than the general version of it. Dead space is the answer to the missing dose. A fixed-needle insulin syringe holds a few microlitres in the hub and needle after the plunger bottoms out, and on small draws that is a measurable percentage of every dose. Across ten draws it adds up to most of an eleventh, which is exactly the "nine draws from a ten-dose vial" complaint. Luer-lock syringes are worse; low-dead-space fixed-needle designs are better.
SarahChen_PharmD said:The arithmetic is right and one caveat matters: a U-40 syringe changes the markings, not the volumes.
This matches mine closely enough to be worth saying so. Do it in two steps and it stops being confusing. First concentration: 10mg into 2ml is 5mg/ml. Then volume: a 0.5mg dose is 0.5 ÷ 5 = 0.1ml. Then units, and this is where people go wrong — a U-100 syringe is graduated in hundredths of a millilitre, so 0.1ml is 10 units. The word "units" has nothing to do with milligrams; it is a volume marking that exists because insulin happens to come at 100 units per ml.