True about zero order kinetics:
Ans. (a) Rate of elimination independent of plasma concentrationRef Review of Pharma by Dr. Gobind-Sparsh 7th ed. / 5* In pharmacokinetics, drugs clearance, rate of elimination and half life is given by the order of kinetics i.e. by zero order kinetics or first order kinetics.Zero order kineticsFirst order kineticsRate of elimination is independent of plasma concentrationRate of elimination is directly proportional to plasma concentrationClearance is more at low concentration and less at high concentrationClearance remains constantHalf life less at low concentration, more at high concentrationHalf life- constantConstant amount of drug is eliminated per unit of timeConstant fraction of drug eliminated per unit of timeOnly few drugs follow zero order kineticsMost of the drugs follow first order kinetics NOTE: drugs which follow zero order kinetics: (WATT- Power)* Warfarin* Alcohol/aspirin* Theophylline* Tolbutamide* Phenytoinkinetics in a Nutshell:Zero orderFirst order* ROE = constant* CLal/P.C.* tl/2 a PC* ROEaP.C.* CL = constant* tl/2 = constant
Rate of elimination is independent of plasma concen- tration
Rate of elimination is dependent on plasma concentration
Clearance of drug is always constant
Half life of drug is constant
Pharmacokinetics