A vial contains 1 g of capreomycin in a 10-mL vial for reconstitution prior to injection. According to the package insert, when 2.15 mL of diluent is added, 2.85 mL of injection is prepared and when 3.3 mL of diluent is added, 4 mL of injection is prepared. How many milliliters of diluent should be added to prepare an injection containing capreomycin, 300 mg/mL?

2.63 ml of diluent should be added to prepare an injection containing capreomycin, 300 mg/mL

Explanation:

300 mg/ml is 0.3 g/ml

1g of capreomycin  was contained

volume of solution = mass of capreomycin / ( concentration of capreomycin solution)

= ( 1g) / ( 0.3g/ml) = 3.33 ml

Now when 2.15 ml diluent added we got solution volume as 2.85 ml

Therefore, volume by capreomycin = 2.85 - 2.15 = 0.7 ml

1g capreomycin occupies 0.7 ml

volume of dilent needed = injection volume - volume occupied by capreomycin

volume of dilent needed = 3.33ml - 0.7ml

volume of dilent needed = 2.63 ml