Indiana Qualified Medication Assistant (QMA) State Practice Exam

What percentage of a medication is typically gone from the bloodstream after one half-life?

1. 10%

2. 25%

3. 50%

4. 75%

The correct answer is: 50%

The concept of half-life is fundamental in pharmacology as it relates to how long a drug remains active in the body. The half-life of a medication is defined as the time it takes for the concentration of the drug in the bloodstream to decrease by half. Therefore, after one half-life, exactly 50% of the medication will have been eliminated from the bloodstream, meaning that 50% remains. This understanding of half-life is critical in medication administration and management, as it impacts dosing schedules and the timing of subsequent doses. Knowing that 50% is the remaining concentration after one half-life helps healthcare professionals predict how a drug will behave in the body over time, which is essential for ensuring medication effectiveness and safety. In contrast, the other answer choices suggest different percentages of drug elimination that do not align with the definition of half-life: 10% and 25% imply that only a small portion of the drug has been eliminated, while 75% suggests that a significant portion is already gone, which contradicts the established definition. Understanding this pharmacokinetic principle is important for anyone working with medications, particularly in a clinical setting as a Qualified Medication Assistant.