Basic Drug Calculations: Problem 10

Ordered:  Nafcillin 900 mg IVPB q6h for a 27 kg child.   Available:  Dry powder in 1 g vials.   Admin.. set:  60 gtts/ml.  The vial states to reconstitute with 3.4 ml diluent to produce 1g/4 ml with concentration of 250 mg/ml. The medication book recommends giving a concentration of 100 mg/ml, duration of infusion 10-20 minutes.

How much fluid will you need to add to the medication drawn up to achieve the recommended concentration?

Need 100 mg/ml    Ordered 900 mg

100 mg : 1 ml ::  900 mg : x

100 x = 900

x = 900/ 100  =  9 mls  (total needed)

9 ml - 3.6 ml = 5.4 ml  (amount to add)

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