Question

When 23 mL of water for injection is added to a drug-lyophilized powder, the resulting concentration is 200,000 units per mL. What is the volume of the dry powder if the amount of drug in the vial was 5,000,000 units? .

Answer 1

2 mL

Explanation:

Given:

Volume of water for injection = 23 mL

Resulting concentration = 200,000 units per mL

Amount of drug in the vial = 5,000,000 units

Now,

Let the final volume of the solution be 'x' mL

Now, concentration =
`\frac{\textup{units of the powder}}{\textup{Total volume of the soltuion}}`

thus,

200,000 =
`\frac{\textup{5,000,000}}{\textup{x}}`

or

x = 25 mL

also,

Total volume 'x' = volume of water + volume of powder

or

25 mL = 23 + volume of powder

or

Volume of powder = 2 mL