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Flashcards in 1: Clinical Pharmacokinetics Deck (27):
1

equation for concentration

[C] = M/V

2

pharmacokinetics (PK) vs. pharmacodynamics (PD)

PK: what the body does to the drug
-how the [drug] changes as it moves through different compartments of your body
-drug disposition: ADME

PD: what the drug does to the body
-describe the relationship b/w the [unbound drug] at the receptor and drug response
-potency, drug effect

PK predicts PD

3

fundamental hypothesis simple statement

predictable relationship b/w plasma (or serum) concentration of drug and its effect

4

3 general goals of PK

-establishing/adjusting dosage regimens
-diagnosis of toxicoses
-withdrawal times for food safety in babies

5

AUC

area under the curve - describes the 'behavior' (exposure) of the drug moving through the body

6

bioavailability, F

% of drug entering into circulation
= (% absorbed)(1-Eh)
=AUC (p.o.)/ AUC (i.v.)

7

Eh (hepatic extraction ratio)

fraction of drug extracted by liver in FPM
=(C1-C2)/C1

8

effects of hepatic extraction on bioavailability

low Eh drugs have higher F
-changing enzymatic activity doesn't significantly change Cp

high Eh drugs have lower F
-changing enzymatic activity does significantly change Cp

9

relative bioequivalence, Fr

= AUC generic/ AUC brand

two considered equivalent if 0.8

10

which form of a drug is active: bound or unbound?

unbound

11

apparent volume of distribution, Vd

-constant relating the amount of drug in the body to the plasma drug concentration
= total drug in body (A)/ plasma [drug] (Cp)

12

why can Vd be much larger or smaller than the physical volume?

uneven distribution in different compartments

13

factors affecting Vd

-MW (drug)
-polarity (drug)
-permeability (drug)
-solubility (drug)
-BINDING (drug and patient)
-blood vol/flow (patient)
-size of organ (patient)
-transporters (patient)
-disease status (patient)

14

steady state concentration, Css

[drug] where rate of drug input = rate of drug elimination

15

maintenance dose rate, DR

rate of drug input to maintain the [drug] at steady state
= (CL)(Css)

16

loading dose vs. maintenance dose

loading dose reached Css faster than maintenance dose

17

loading dose

= (Vd)(target Cp)

18

definition of drug metabolism

IRREVERSIBLE transformation of parent compounds into daughter compounds --> can either terminate action or bioactivate

19

what is the path by which most drugs are excreted?

renal

20

clearance, CL

volume of drug eliminated per unit time
-constant for drug and patient
= dose/ AUC
=

21

elimination rate, ER

mass of drug eliminated per unit time
= (CL)(Cp)

22

elimination rate constant, K or Ke

percent of drug eliminated per unit time
= CL/Vd

23

when DR remains the same, how will changing CL alter Css?

changing CL will proportionately and inversely change the Css

24

organ x clearance, CLx

= organ extraction ratio (Ex) x organ blood flow (Qx)

25

for drugs extensively metabolized by the liver, describe how Eh and Q affect CL

Eh is almost fixed and will barely affect CL, so CL will mainly be determined by Q

-important for drug-drug interactions when hepatic drug metabolism is induced/inhibited and in certain conditions that affect blood flow

26

for drugs with high Eh, how will increased hepatic metabolism affect F and CL?

decreased F
no change in CL

27

for drugs with low Eh, how will increased hepatic metabolism affect F and CL?

no change in F
increased CL