Detailed Explanation
The half-life provides a convenient summary measure of how long a drug persists in the body, integrating all the elimination processes that remove the drug from systemic circulation. After each half-life interval, approximately 50% of the remaining drug is eliminated, resulting in an exponential decay pattern. After five half-lives, approximately 97% of a drug has been eliminated, a principle relevant to both washout period design and achievement of steady-state concentrations with repeated dosing.