After four half-lives, what is the percentage of drug clearance?

The concept of half-lives is integral to understanding how drugs are cleared from the body. Each half-life represents the time required for the concentration of a drug in the bloodstream to reduce by half. When analyzing what happens after four half-lives, we can use exponential decay to compute the remaining percentage of the drug.

Starting with 100% of the drug, after the first half-life, 50% remains. After the second half-life, the remaining amount is halved again, resulting in 25%. Continuing this pattern:

• After the third half-life, 12.5% remains.

• After the fourth half-life, 6.25% remains.

Therefore, if 6.25% of the drug is still in the body, that translates to a clearance of 93.75%.

Thus, the correct understanding of how drug elimination works through multiple half-lives directly leads to the conclusion that after four half-lives, 93.75% of the drug has been cleared from the body, which directly supports the chosen answer.