A physician prescribes an intramuscular dose of 200,000 units of penicillin G benzathine. If the label reads 300,000 units/mL, how many milliliters of medication does the nurse prepare?

To determine the correct volume of penicillin G benzathine to prepare, you can use the formula that relates the prescribed dose, concentration, and volume. The formula can be expressed as:

Volume (mL) = Desired Dose (units) / Concentration (units/mL)

In this situation, the desired dose is 200,000 units, and the concentration from the label is 300,000 units/mL. Plugging in these values:

Volume (mL) = 200,000 units / 300,000 units/mL

Calculating this gives:

Volume (mL) = 200,000 / 300,000 = 0.6667 mL

When rounded, this value is approximately 0.7 mL. Therefore, the nurse should prepare 0.7 mL of penicillin G benzathine to meet the prescription.

This calculation showcases an essential aspect of pharmacology: understanding how to convert dosages based on concentration to ensure accurate delivery of medication. Practicing these types of calculations is vital for safe medication administration.