The client receives 200 mg of a medication on a consistent schedule. How much drug is in the body at 4 half-lives?

Here's the process for calculating the drug concentration after multiple half-lives: First half-life: After 1 half-life, 50% of the original dose remains in the body. 200 mg x 0.50 = 100 mg remains after 1 half-life. Second half-life: After 2 half-lives, 50% of the remaining drug will be eliminated. 100 mg x 0.50 = 50 mg remains after 2 half-lives. Third half-life: After 3 half-lives, 50% of the remaining drug will be eliminated again. 50 mg x 0.50 = 25 mg remains after 3 half-lives. Fourth half-life: After 4 half-lives, 50% of the remaining drug will be eliminated once more. 25 mg x 0.50 = 12.5 mg remains after 4 half-lives. Now, we need to sum up the amount of drug remaining in the body at each half-life: After 4 half-lives, there are 12.5 mg left from the original dose. Total drug in the body after 4 half-lives = 200 mg - 12.5 mg = 375 mg.