Nurses use proportions to determine the amount of drug to ad

Nurses use proportions to determine the amount of drug to administer when the dose of the drug is measured in mg, but the drug is packaged in a diluted form in mL. For example, to find the number of milliliters of fluid needed to administer 300 mg of a drug that comes packaged as 120 mg in 2 mL of fluid, a nurse sets up the proportion StartFraction 120 mg Over 2 mL EndFraction equals StartFraction 300 mg Over x mL EndFraction where x represents the amount to administer in milliliters. Use this method to find the correct dose for 125 mg of a drug packaged as 100 mg in 2-mL vials.

Solution

The proportion of the dose of a drug by mg to the dose by ml is 100/2 or, 50/1. Thus for administering 60 mg of a drug, 1 ml of the drug has to be given. Let x ml be the volume of drug required for administering 125 mg of a drug. Then 50/1 = 125/x or, x = 125/50 = 2.5 ml. Thus, for administering 125 mg of a drug, 2 and a quarter vials of the drug have to be given.( A quarter of a vial of 2 ml is (1/4)*2 = 0.5 ml).