Pharmacokinetics Exam 3 Review

Flashcards created to review key pharmacokinetic concepts for Exam 3.

What is clearance in pharmacokinetics?

The rate at which a drug is removed from the body.

Define elimination.

ANYTHING that the body is getting rid of (intact drug, active metabolite, inactive drug, etc.).

What does eGFR stand for and what is its value?

Estimated Glomerular Filtration Rate; typically around 125 ml/min.

What is the difference between excretion and elimination?

Excretion refers specifically to the body getting rid of intact drugs.

What process is mediated by OATs?

Transport of acids (and negatively charged compounds).

What pushes the drug into the kidney for filtration?

Hydrostatic pressure.

When does reabsorption of drugs occur in the kidneys?

When the concentration of the drug is lower in the tubules than in the surrounding blood.

What is intrinsic clearance?

Metabolic efficiency of an enzyme.

What mainly determines interperson drug variability?

Drug metabolism.

What is the rate limiting step in the renal system?

Uptake by renal epithelial cells.

What is the goal of phase 1 reactions in drug metabolism?

Functionalization; adding or exposing a polar group on the molecule.

What are phase 2 reactions?

Conjugation (synthetic) reactions that transfer a conjugating moiety to the drug.

How do you enhance the excretion of a weak base?

Lower the pH (acid flush).

What effect does enzyme induction have on drugs with a low E value?

It has a greater impact, allowing the drug to be more easily eliminated.

What is the main substrate of CYP1A2?

Caffeine.

What is a CYP3A4 inhibitor?

Ketoconazole or Ritonavir.

What does a CLR ratio of ~1 mean?

Only filtration is occurring.

What are the main barriers to intrinsic clearance in the liver?

How much drug actually goes into the liver, transporters, and protein binding.

What does a CLR ratio of > 1 indicate?

Active secretion is occurring.

Which statin is a substrate of CYP2C19?

Rosuvastatin.

What is the formula for calculating Fe?

Ke / K10.