First-order kinetics Single-dose pharmacokinetics 6 First-order kinetics: A constant fraction of the remaining amount of drug is eliminated per unit time. 0 0 5 A Time(h) Zero-order kinetics 8 Zero-order kinetics: 6 A constant amount of drug is eliminated per unit time. 0 0 1 2 3 B Time(h)First-order kinetics: A constant fraction of the remaining amount of drug is eliminated per unit time. Single-dose pharmacokinetics Zero-order kinetics: A constant amount of drug is eliminated per unit time