Question

Pharmacy Calculations please use conversion factors as well as show the bridges between metric and imperial system if possible. Thanks so much!

Example 1 An antibiotic suspension contains 250 milligrams of drug in 1 teaspoon of medication. How many grams of drug are contained in 2 tablespoons of medication? Figure 48) Example 5 Four (4) grams of potassium chloride are dissolved in enough water to make 25 millliters of product. What's the final percent concentration of the product? Example 4 How many milliliters of a 2% solution can be prepared from 1 00 milliliters of a 5% solution? Example 6 Ninety (90) milliliters of glycerin are added to 600 milliliters of water to make a product. What's the percent VV of the final product? Example 7 A prescription ointment contains 0.002% w/w of beclomethasone. How many milligrams of beclomethasone are contained in 2 ounces of ointment?

Answer 1

1) concentration of the suspension = 250 milligrams drug in 1 teaspoon medication.

Two teaspoons contain double the medication. Hence it contains double the drug.

which is 2*250 = 500 milligrams.

5) Weight of potassium chloride dissolved = 4 grams

Final volume of solution = 25 millilitres

As solute and solution are given in grams and millilitres, concentration percentage will be in (w/v)%

Percentage concentration of solution is (weight of KCl in grams/volume of solution in millilitres)*100

which is (4/25)*100 = 16% w/v

4) Volume and concentration of given solution is 100ml and 5%.

Let us suppose it is (w/v)%. Then 5 grams of solute is present in 100 ml solution.

Required concentration is 2% and available solute is 5 grams

Then the volume of solution is given by (solute in grams/percentage)*100

which is (5/2)*100 = 250 ml

250 millilitres of 2% solution can be prepared.

6) Volume or glycerin (solute) is 90 millilitres. Volume of water (solvent) is 600 millilitres.

Volume or solution is ( volume of solute + volume or solvent ) = 90 + 600 which is 690ml

The percentage v/v of solution is (volume or solute in ml / volume of solvent) * 100

which is (90/690)*100 = 13%v/v

7) W/W concentration of ointment is 0.002 % beclomethasone. This means 0.002 grams of beclomethasone is present in 100 grams of drug.

Given weight of ointment is 2 ounces which is 28.35*2 = 56.7 grams

Weight of beclomethasone in this ointment ( percentage * weight of ointment ) / 100 grams

which is ( 0.002 * 56.7 ) / 100 grams = 0.1134 grams or 113.4 milligrams

The weight of beclomethasone in 2 ounces of ointment is 113.4 milligrams

This is a brief explanation for the given calculations.. Hope this helps you out. Please feel free to give a like and contact us if you need further detail explanation. Thank you and have a great day.