Question

Based on the label instructions, adding 4.5 mL of diluent to a vial containing 500 mg of powder will result in a concentration of 100 mg/mL. Calculate the volume of diluent to use if the desired concentration is 50mg/mL.

1. 10 mL
2. 0.5 mL
3. 9.5 mL
4. 1 mL

Answer 1

Answer : 9.5 mL

Based on the label instruction,to find the total volume of medicine after reconstitution with 4.5 mL diluent use this formula

ie, 100 X = 500

X=

X = 5 mL

From the above calculation we know that adding 4.5 mL of diluent result in formation of 5 mL of medicine. ie 0.5 mL volume excess than the diluent. Hence to find the amount of diluent to form a medicine of 50 mg/mL, we need to find the total amount of medicine formed in that particular concentration and substract 0.5 mL from total amount of medicine reconstituted.

Total mL reconstituted to form 50 mg/mL use the following formula

=

50 X = 500

X =

X = 10 mL

Total amount of medicine to form 50 mg/mL = 10 mL

Diluent added to form 50 mg/mL = 10 mL - 0.5 mL

Diluent added to form 50 mg/mL = 9.5 mL