Zero order kinetics means:
Ans. a (A constant amount of drug is eliminated per unit time). (Ref. Pharmacology by KD Tripathi 6th/33, fig. 3.5)ZERO ORDER ELIMINATION# The metabolic pathways responsible for alcohol metabolism are rapidly saturated and that clearance is determined by how fast these pathways can work. The metabolic pathways work to their limit.# This is known as zero order kinetics: a constant amount of drug is eliminated per unit time,# This form of kinetics occurs with several important drugs at high dosage concentrations:- Phenytoin,- Salicylates,- Theophylline, and- Thiopentone (at very large doses).# Because high dose thiopentone is very slow to clear, we no longer use it in infusion for status epilepticus.FIRST ORDER ELIMINATION# A constant fraction of the drug in the body is eliminated per unit time.# The rate of elimination is proportional to the amount of drug in the body.# The majority of drugs are eliminated in this way.Elimination of drugsZero-order elimination Rate of elimination is constant regardless of C (constant amount of drug eliminated per unit time). Cp | linearly with time. Examples of drugs--ethanol, phenytoin, and aspirin (at high or toxic concentrations).First-order elimination Rate of elimination is proportional to the drug concentration (i.e.., constant fraction of drug eliminated per unit time). Cp | exponentially with time
A constant amount of drug is eliminated per unit time
A constant fraction of the drug in the body is eliminated per unit time
The fraction of the administered dose that reaches the systemic circulation.
The effect that can be increased by giving a second agent that boosts the effect of the liver's enzyme system
General Pharmacology