In the metabolism of alcohol, high doses of aspirin & phenytoin, mechanism is -
Ans. is 'c' i.e., Zero order kinetics o The drugs whose kinetics changes from first order to zero order at therapeutic concentration are said to follow pseudo - zero order kinetics or mixed order kinetics or saturation kinetics.o Drugs showing zero/pseudo-zero order kinetics :# Phenytoin# Theophylline# Alcohol# Tolbutamide# Warfarin# Salicylates (Aspirin)# Propanolol (ref- Pharmocolgy recap) First Order KineticsZero Order Kinetics (Non linear Kinetics)1. Constant fraction of drug is eliminated per unit time2. Rate of elimination is proportional to plasma concentration3. Clearance remains constant4. Half life remains constant5. Most of the drugs follow first order kinetics1. Constant amount of the drug is eliminated per unit time.2. Rate of elimination is independent of plasma concentration3. Clearance is more at low concentrations and less at high concentrations4. Half life is less at low concentrations and more at high concentrations5. Very few drugs follow pure zero order kinetics e.g. alcohol6. Any drug at high concentration (when metabolic or elimination pathway is saturated) may show zero order kinetics
First pass kinetics
First order kinetics
Zero order kinetics
Second order kinetics
Pharmacokinetics