6.11 Pharmacokinetics

Question 1

How many half life must pass to assume a kinetic process is almost totally complete?

Answer 1

4 half lives

Question 2

What is a half life?

Answer 2

Time it takes for a kinetic process to be 1/2 completed.

Question 3

What is linear kinetic?

Answer 3

• Relationship between administered dose and achieved plasma concentration.
• For example if you want to increase the serum level by 50% increase the dose by 50%

Question 4

What is first order?

Answer 4

Drug levels decrease a constant Fraction/Percentage per unit of time (linear)

Question 5

What is zero order?

Answer 5

Drug levels decrease a set amount per unit of time (non-linear; Michaelis-Menten enzyme kinetics)

Question 6

What is the two compartment model?

Answer 6

1) Drugs go to organs first

2) Then second distribution is to reach equilibrium.

Question 7

What is Vmax?

Answer 7

Maximum amount of drug that can be eliminated per unit of time.

Question 8

What is Bioavaliability?

Answer 8

Fraction of drug reaching systemic circulation (extent of absorption; gt wall metabolism; efflux transporting, “first pass” effect.)

Question 9

What is Bioequivalence?

Answer 9

• Tradename vs generic
• Compares drug dosage forms; compares a drug dosage form made by different manufacturers.
• To be bioequivalent serum concentration time curves from the two products must be nearly superimposable, or have the same peak level, time to peak level and AUC.
• Drugs can have the same bioavalibility but not be bioequivalent.

Question 10

Define the components of:

Cp= (SxFxDose)/Vd

Answer 10

Cp= Plasma concentration
Vd= Volume of distribution
S=Fraction of drug dose that is active drug
F= Bioavailability

Question 11

What is the “First Pass Effect”?

Answer 11

Dug metabolized by liver before reaching systemic circulation.

Question 12

What is P-glycoprotein?

Answer 12

Protein associated with tumor multi drug resistance; acts as energy requiring efflux pump for many classes of natural products and chemotherapeutic drugs.

Question 13

What is ADME?

Answer 13

Defines a drugs Pharmacokinetic profile
A= Absorption
D= Distribution
M= Metabolism
E= Excretion

Question 14

How are drug serum levels reported?

Answer 14

As an amount per volume, example mcg/mL

Question 15

What is Fick’s Law of Diffusion?

Answer 15

• Diffusion: Flow is from higher concentration to a lower concentration.
• The villi of the upper small intestine provide an extremely large surface area (approximately 20 sq. meters)
• The small intestinal wall is thiner than the stomach cellular lining.
• Effects of rate of diffusion