Which of the following represents an abbreviation that is NOT used for dosages or strengths of medications?

The abbreviation "PD" does not represent a dosage or strength of medications. In the context of medication, "mg" stands for milligrams, which is a unit of mass typically used to express the dosage of solid medications. "ml" represents milliliters, a unit of volume commonly used for liquid medications. "g" stands for grams, which is another unit of mass used for measuring larger dosages than milligrams.

In contrast, "PD" is not a recognized abbreviation for dosage or strength. It often stands for "prn," meaning "as needed," in other contexts, but it does not have a standard role in indicating medication dosages. Understanding the meaning of these abbreviations is essential for properly administering medications and ensuring patient safety.