Question

How many grams of anhydrous dextrose should be used in preparing 1 liter of a ½% isotonic ephedrine sulfate nasal spray?

Ans: 43.61 g

Answer 1

Sodium chloride equivalent of ephedrine sulphate is 0.23

Sodium chloride equivalent of dextrose is 0.16

Isotonic NaCl is 0.9% w/v, which is 9 g in 1000 ml. The ephedrine is 1/2% w/v, which is 5 g in 1000 ml, or 5 x 0.23 = 1.15 g Na equivalent.

Subtracting that, 9-1.15 = 7.85, so we have to find 7.85 g Na equivalent in the form of dextrose to make the total up to 9.

.We therefore need 7.85/0.16 = 49.0625 g dextrose.

All this dextrose is hydrous one

We need anhydrous on

Moles of hydrous dextrose = mass / molar mass = 49.0625/198.171 = 0.2475

In 1 mole of hydrous dextrose ---> there will be 1mole of anyhydrous dextrose and 1 moleof water

Mass of anhydrous dextrose = 0.247*180 = 44.46 gms