Question

Scopolamine is available as a 0.4mg/1ml vial. You are asked to prepare scopolamine 1000mcg/100ml NS drip. How many mls of scopolamine should be added to the 100ml bag of NS ?

Answer 1

Explanation

Conversion of milligram, mg to microgram, mcg

Note: 1 mg = 1000 mcg

So 0.4 mg scopolamine in 1 ml vial will be

$\frac{0.4mg\times1000\text{mcg}}{1mg}=400\text{mcg}$

Note also that 0.01 mcg is equaivalent to 1.0 x10⁻⁵ mL.

This implies

$\begin{gathered} 0.01mcg=1.0\times10^{-5}mL \\ 1000\text{mcg}=xmL\text{ scopolamine} \\ \\ \text{xmL scopolamine }=\frac{1000mcg\times1.0\times10^{-5}mL}{0.01mcg}=\frac{0.01mL}{0.01}=1ml \end{gathered}$

Therefore 1 mL of scopolamine should be added to the 100 mL of NS