Lessons · Pharmacy · a child's dose, as the order writes it
A child's dose, exactly as the order writes it
A child's dose is worked from the milligrams per kilogram the order gives and the child's weight, and from nothing else.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
What it is for
The parent at the window is holding an oral syringe and waiting for a number in millilitres. Everything before that number is arithmetic you can check; the milligrams per kilogram itself is the prescriber's, and if it is not on the order, the answer is a phone call and not a calculation.
How to think about it
Four lines, in order, every time. Weight in kilograms. Milligrams from the mg/kg the order gives. Milligrams per millilitre from the stock bottle. Millilitres from the two. Write the unit on every line so a slipped step is visible.
Worked example
Order: 12 mg/kg per doseGiven by the order. This track never invents one and never scales an adult dose down.
Weight: 33 lb / 2.2 = 15 kgPounds into kilograms first.
12 mg/kg x 15 kg = 180 mg per doseThe multiplication.
Stock 100 mg / 5 mL = 20 mg/mL, so 180 / 20 = 9 mLThen the volume, off the bottle on the shelf.
Your turn
An order gives 8 mg/kg per dose and the child weighs 12 kg. Write the dose in milligrams.
8 x 12 = mg
Solve one, graded on the server
The trap
Reaching for an old rule of thumb that scales an adult amount by a child's age. Those rules are not used here and they are not used in a pharmacy. The order gives the milligrams per kilogram, or the prescriber is called.