If a patient requires 500 mg of a medication and the stocking concentration is 250 mg/5 ml, how many ml are needed?

To determine how many milliliters are needed to provide a patient with 500 mg of medication, given a stocking concentration of 250 mg per 5 ml, you can set up a proportion based on the concentration provided.

First, find out how many milligrams are in 1 ml by dividing the amount of medication in the stocking solution by its volume:

250 mg / 5 ml = 50 mg/ml.

Next, to find out how many milliliters are needed to achieve 500 mg, you can use the concentration found. Set up the equation:

Amount needed (500 mg) = Concentration (50 mg/ml) × Volume (ml).

Now, rearranging the equation to solve for volume gives:

Volume (ml) = Amount needed (mg) / Concentration (mg/ml).

Substituting in the values:

Volume (ml) = 500 mg / 50 mg/ml = 10 ml.

This calculation indicates that, to provide the patient with the required 500 mg, you would need 10 ml of the solution. Thus, the correct response is indeed that 10 ml is required.