If a prescription calls for 200 mg of a drug in a 100 mL solution, what is the concentration in mg/mL?

To determine the concentration of a drug in a solution, you need to divide the total amount of the drug by the total volume of the solution. In this case, you have 200 mg of the drug in a 100 mL solution.

By performing the calculation:

Concentration (mg/mL) = Total amount of drug (mg) / Total volume of solution (mL)

Substituting the values from the question:

Concentration = 200 mg / 100 mL = 2 mg/mL.

Thus, the concentration of the solution is correctly calculated as 2 mg/mL. This concentration indicates that there are 2 milligrams of the drug present in every milliliter of the solution, which is a crucial calculation for correctly dosing medications.