True about first order kinetics is:
A constant amount is eliminated in unit time
The half-life increases with an increase in dose
The rate of elimination is constant
The rate of elimination is proportional to the plasma concentration
Ans. d. The rate of elimination is proportional to the plasma concentration (Ref: Katzung 12/e p43-44: KDT 7/e p30-31, 6/e p31-32)Rate of elimination is proportional to plasma concentrationQ first order kinetics (Linear kinetics).First Order Kinetics (Linear kinetics)Zero Order Kinetics (Non linear Kinetics)* Constant fraction of drug is eliminated per unit of timeQ.* Rate of elimination is proportional to plasma concentrationQ.* Clearance remains constantQ.* Half-life remains constantQ.* Most of the drugs follow first order kineticsQ.* Constant amount of the drug is eliminated per unit timeQ.* Rate of elimination is independentQ of plasma concentration.* Clearance is more at low concentrations and less at high concentrationsQ.* Half-life is less at low concentrations and more at high concentrationsQ.* Very few drugs follow pure zero order kinetics e g. alcoholQ* Any drug at high concentration (when metabolic or elimination pathway is saturated) may show zero order kineticsQ.
Pharmacokinetics