For a drug that follows IBD1 kinetics, the concentration of the drug in the body after half of a half- life has passed = _____% initial concentration (Co). Round your answer to the nearest integer. For a drug that follows IBD1 kinetics, it takes one half-life to eliminate 50% of the drug in the body. The time it takes to eliminate 90% of the drug in the body is ______half-lives. Round your answer to the nearest integer.