Zero order kinetics occur in which of the following drug with high doses?
When high doses of ceain drugs are given their mechanism of elimination gets saturated and elimination kinetics changes from first order to zero order. Examples of such drugs are phenytoin, propranolol, theophylline, salicylates, and tolbutamide. Drugs that obey zero order kinetics are phenytoin, salicylates, ethanol, furosemide and indomethacin. In zero order kinetics only a constant amount of drug is excreted rather than a constant percentage or propoion. For drugs exhibiting zero order kinetics small increments in dose may cause dispropoionately large increase in serum concentration. Clearance and t1/2 of the drug varies with concentration of the drug. I st order kinetics: In this type of elimination, a fixed fraction of the drug present in the body is eliminated in unit time. Most of the drugs follow this type of kinetics. It works within physiological limits until elimination mechanisms are saturated. Ref: Pharmacology ReCap 2.0 for Bachelor of Dentistry Students By Dr. J. G. Buch page 25. Pediatric Critical Care Medicine: Basic Science And Clinical Evidence edited by Derek S. Wheeler, page 163.
Phenytoin and Propranolol
Digoxin and Propranolol
Amiloride and Probenecid
Lithium and Theophylline