Drug Metabolism: Drug Elimination

Question 1

What is the main organ involved in drug excretion?

Answer 1

The kidneys

Question 2

How does drug excretion work?

Answer 2

Within the kidneys, water and electrolytes are reabsorbed into the bloodstream but the polar molecules produced in phase II metabolism are excreted into the urine

Question 3

What does drug elimination follow?

Answer 3

The michaelis-menten kinetics

Question 4

How does drug elimination relate to the michaelis-menten kinetics?

Answer 4

At first, the drug is eliminated with 1st order kinetics where an increase in drug plasma concentration would be directly proportional to the increase in drug elimination. However, as the elimination mechanisms become saturated it leads to a 0 order kinetics (curve flatlines)

Question 5

Which equation can be used to model the rate of elimination?

Answer 5

Michaelis-menten equation RE = Vmax X [drug]plasma / Km + [drug]plasma