7mcg X 100 Kg x 60 minutes/hr = 42,000 mcg/hr / 1000mcg/mg = 42mg/hr
I find if I work this out in a linear fashion, it is much easier to see what I am solving for, i can cancel out my units as I go along.
You can check it like this:
42mg/hr X 1000mcg/mg = 42,000 mcg/hr
42,000mcg/hr / 60minutes/hr = 700mcg/minutes / 100kg = 7mcg/kg/minute
Rather you prefer to work out the problem in a linear matter or using dimensional analysis, always go back and check your work, make sure you WRITE down the units you are solving for and cancel them out appropriately. If you follow all of those steps, you will succeed at Pharm math!!
Trina Belair, MSN, FNP-C