Drug Clearance Via Metabolism

Question 1

What are the 3 major routes of elimination?

Answer 1

Hepatic metabolism, elimination in bile, elimination in urine

Question 2

What is first-order kinetics?

Answer 2

A constant fraction of drug is metabolized per unit of time. Linear kinetics.

Question 3

What is zero-order kinetics?

Answer 3

The rate of metabolism remains constant over time. A constant amount of drug is metabolized per unit of time and the rate of elimination is constant and does not depend on the drug concentration. Nonlinear kinetics.

Question 4

What is phase I metabolism?

Answer 4

Phase I reactions convert lipophilic molecules into more polar molecules. Phase I metabolism may increase, decrease, or leave unchanged the drug’s pharmacologic activity.

Question 5

What is phase II metabolism?

Answer 5

This phase consists of conjugation reactions. Some drugs directly enter phase II metabolism without entering phase I metabolism first.