Question

1. Case:  A prescription for calls for compounding 60 mL of an oral solution for patient A.  This oral solution contains 45 mg of salicylic acid. The pharmacist decides to weigh this on a balance with a minimum weighable quantity of 120 mg and dissolve it an appropriate solvent to prepare the solution. Answer the following questions to explain how you will use the liquid measurement aliquot method to obtain the correct amount of salicylic acid to prepare this solution. When making this preparation, you want to minimize the amount of salicylic acid that is wasted.  The prescription is as follows:

Rx  Salicylic acid                            45 mg

      Cherry flavor solution             5 mL

      Ora-Syrupee                qs        60 mL

1. What is the target amount of salicylic acid for the liquid aliquot that will be used to make the 60 mL oral solution?

2. What is the maximum volume of the liquid aliquot can be used to make this preparation?

3. If you weigh 120 mg of salicylic acid on your balance and want to use an aliquot volume of 15 mL, how much solvent will you use to dissolve the 120 mg of salicylic acid.

Please give clear and detail answers to each part of the question

Answer 1

1. What is the target amount of salicylic acid for the liquid aliquot that will be used to make the 60 mL oral solution?

Amount of salicylic acid = 120mg

Liquid aliquot used = 60ml

Weight of drug in aliquot = x mg

Volume of solution = 60ml

We know that , Weight of drug in volume /Volume of the solution = weight of the drug in aliquot / aliquot volume

so 120mg/60ml = x/60ml

Therefore the target drug need is 120 mg

2.If you weigh 120 mg of salicylic acid on your balance and want to use an aliquot volume of 15 mL, how much solvent will you use to dissolve the 120 mg of salicylic acid.

Using the same equation given above

Weight of drug in volume /Volume of the solution = weight of the drug in aliquot / aliquot volume

120mg/x=120/15

Liquid aliquot required = 15ml