78. PK

Question 1

Absolute bioavailability (F) equation

Answer 1

F(%) = 100 x (AUC extravascular / AUC IV) * (Dose IV / Dose extravascular)

Question 2

Ca corrected equation

Answer 2

Ca corrected = Serum Ca + [(4 - albumin)*0.8]

Question 3

Phenytoin corrected equation

Answer 3

Phenytoin corrected = total phenytoin measured / [(0.2 * albumin) + 0.1]

Question 4

Volume of Distribution (Vd) equation

Answer 4

Vd = amount of drug in body / conc of drug in plasma

Question 5

Elimination Rate Constant (Ke) equation

Answer 5

Ke = Cl / Vd

Question 6

Predicting Drug Conc equation

Answer 6

C2 = C1 x e^(-k*t)
Ke = ln (C1/C2) / t

Question 7

Half-life (t1/2) equation

Answer 7

t1/2 = 0.693 / ke

Question 8

Loading Dose (LD) equation

Answer 8

LD = (Desired conc * Vd) / F

Question 9

Rate of absorption of formulation types from fastest to slowest

Answer 9

IV, SL, ODT, IR tabs, ER tabs

Question 10

Ways to increase dissolution rate

Answer 10

Reduce particle diameter = increase surface area (micronized)
Increase solubility

Question 11

A drug with ___ absorption has high bioavailability (>___%)

Answer 11

good, >70%

Question 12

A drug with ___ absorption has low bioavailability (<___%)

Answer 12

bad, <10%

Question 13

Calculating equivalent dose of drug in different formulation

Answer 13

Dose of new dosage form = (amount absorbed from current dosage form) / (F of new dosage form)

Question 14

Factors that favor greater drug distribution:

Answer 14

High lipophilicity
Low molecular weight
Unionized status
Low protein binding

Question 15

Weak base drug → increase excretion by ___ urine

Answer 15

acidifying

Question 16

Weak acid drug → increase excretion by ___ urine

Answer 16

alkalinizing

Question 17

Clearance (Cl) equation

Answer 17

Cl = Rate of elimination / Drug Conc
Cl = Dose / AUC

Question 18

___, ____, and ____ exhibit Michaelis-Menten Kinetics (saturable mixed order, or non-linear kinetics)

Answer 18

Phenytoin, theophylline, and voriconazole

Question 19

Takes about ___ half-lives to reach steady state (assuming first-order kinetics in a one-compartment distribution model and no loading dose has been given)

Answer 19

5

Question 20

Takes about ___ half-lives to eliminated >95% of the drug if no additional doses are given

Answer 20

5

Question 21

Peak level (for IV) is taken ____

Answer 21

30 min after end of infusion

Question 22

Trough level is taken ____

Answer 22

immediately (or within 30 min) before next dose is due

Question 23

What is a primary pathway of drug degradation in the gut?

Answer 23

Hydrolysis

Question 24

____ is what the drug does to the body

Answer 24

Pharmacodynamics

Question 25

___ is what the body does to the drug

Answer 25

Pharmacokinetics

Question 26

Rate of dissolution is described by ___ equation

Answer 26

Noyes-Whitney

Question 27

Phase I metabolic reactions examples

Answer 27

Reduction, hydrolysis, and oxidation