How many mL will you prepare for the correct dose?

Question

Order: kanamycin sulfate, 150 mg IM q6h
Available: a vial containing 500 mg of kanamycin powder; you will add 4.2mL of sterile water, yielding a solution of 100mg = 1mL.
How many mL will you prepare for the correct dose?

Answer 1

Formula: Stock desired over stock on hand x volume.

Given: SD=150 mg
SH= 100 mg
Volume: 1 ml

= 150 mg / 100 mg X 1 ml
= 1.5 ml

The dose to be administered will be 1.5 ml q6h.

Answer 2

1.5 mL

You can figure this one out without using the formula. 1ml contains 100 mg dosage, but you need 150 mg so you need another .5