dosage and calculation

Question

A dose of an opioid medication (45 mg) and an anticholinergic medication (0.3 mg) has been ordered for preoperative sedation. The opioid medication is provided in a prefilled syringe containing 50 mg/mL and the anticholinergic medication is provided in a vial containing 400 mcg/mL. What is the total volume that the nurse will inject?

Answer 1

Let's take a look at the opioid med first:

50 mg / ml and you need 45 mg, so clearly you need less than 1 ml. How much less?

45 mg x 1 ml / 50 mg = 0.90 mls of the opioid med

Next, the same for the anticholinergic:

400 mcg / ml and you need 0.3 mg.

First, we'll convert the 400 mcg/ml to mg/ml so we are working in the same units.

400 mcg/ml x 1 mg/1000 mcg = 0.4 mg/ml

You need 0.3 mg, so clearly you need less than 1 ml. How much less?

0.3 mg x 1 ml/0.4 mg = 0.75 mls of the anticholinergic is needed

Total volume to be injected = 0.9 mls + 0.75 mls = 1.65 mls