First order kinetics is: September 2005

Ans. C: Elimination of the drug is propoional to the serum concentration. A 0-order kinetics has a rate which is independent of the concentration of the reactant(s). Increasing the concentration of the reacting species will not speed up the rate of the reaction. Zero-order reactions are typically found when a material that is required for the reaction to proceed, such as a surface or a catalyst, is saturated by the reactants. With first-order elimination, the rate of elimination is directly propoional to the serum drug concentration (SDC). There is a linear relationship between rate of elimination and SDC. Although the amount of drug eliminated in a first-order process changes with concentration, the fraction of a drug eliminated remains constant. The elimination rate constant (Kel) represents the fraction of drug eliminated per unit of time.