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Pharmacology > 1. Pharmacokinetics and Pharmacodynamics > Flashcards

1. Pharmacokinetics and Pharmacodynamics Flashcards

1
Q

pharmacokinetics

A

how the body handles the drug

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2
Q

pharmacodynamics

A

effect of the drug on the body

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3
Q

ADME components

A

Absorption
- extent/rate
Distribution
Metabolism
Excretion

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4
Q

A+D

A

drug IN

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5
Q

M+E

A

drug OUT

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6
Q

AUC

A

area under curve
reflects actual body exposure to drug after administration of a dose of drug
mg*h/L

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7
Q

factors that influence oral drug absorption

A

1)GI tract acidity
2)bowel disorder hx

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8
Q

factors that influence IM drug absorption

A

1)muscle mass
2)pain/necrosis complications
3)skin/muscle irritation
4)delayed/unpredictable onset

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9
Q

physiochemical properties that may influence ADME

A
  • solubility
  • partition coefficients
  • ionization
  • pKa
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10
Q

solubility

A

if a drug is lipophillic or lipophobic

the more aqueous the solution, the more rapidly it is absorbed

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11
Q

partition coefficients

A

ratio of drug split into oil phase vs aqueous concentration

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12
Q

higher partition coefficient

A

higher permeability
faster drug absorption

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13
Q

ionization

A

weak acid vs weak base
how quickly does it ionize in aqueous solution

charged molecules do not cross membranes by diffusion

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14
Q

pKa

A

the pH at which 50% of the drug is ionized and 50% of the drug is neutral

ration of
unionized:ionized

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15
Q

higher pKa

A

higher pKa = slower movement of compound into the tissue

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16
Q

prodrug

A

inactive precursors that are metabolized into active metabolites

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17
Q

why are prodrugs used

A

to improve how active drug is A, D, M, or E

to increase aqueous solubility

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18
Q

prodrug examples

A

Fospropofol
fosphenytoin
valacyclovir

Slide 26

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19
Q

bioavailabilioty

A

how much drug is actually available systemically after first pass/second pass of metabolism

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20
Q

first pass

A

metabolized by the liver

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21
Q

low first pass drug

A

bypass the liver
more drug available
IV drugs

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22
Q

high first pass drug

A

pass through liver
less drug available
Ca channel blockers
beta blockers
diuretics
lidocaine

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23
Q

“F”

A

Bioavailability (F) is defined as the rate and extent to which the active constituent or active moiety of a drug is absorbed from a drug product and reaches the circulation

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24
Q

F=1.0

A

both routes deliver the same amount of drug to target organ

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25
Q

For an IV drug, if F is close to 1.0

A

use a lower loading dose
almost all drug reaching circulation

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26
Q

For an Oral drug, if F is low («1.0)

A

use a higher loading dose
not enough drug reaching circulation

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27
Q

Phase 1
(nonsynthetic)
Drug metabolism

A

involve intramolecular modifications:
Hydrolysis
Oxidation
Reduction

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28
Q

Phase 2
(synthetic)
Drug metabolism

A

conjugation of the drug with an endogenous substance by
Glucuronidation
Methylation
Acetylation
Sulfation

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29
Q

Cytochrome P 450 system

A

CYP450 enzymes
- 1A2, 2C9, 2C19, etc

root of many drug interactions

if 2 drugs are taken together and they both are metabolized through the CYP450 system, they will take longer to metabolize.

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30
Q

hepatic enzyme induction

A

slow onset
long duration

prevents activation of drug metabolism in liver

expect increase in elimination rate (decrease 1/2 life)

drug does not stay in the body long

not many inducers

31
Q

hepatic enzyme inhibition

A

rapid onset
short duration

stimulates activation of drug metabolism in liver

expect decrease in elimination rate
(increased 1/2 life)

drug stays in body longer

many inhibitors

32
Q

more-protein bound drug

A

more narrow therapeutic range

33
Q

protein binding range

A

0-99%

34
Q

albumin

A

high capacity
low affinity

35
Q

alpha 1 acid glycoprotein

A

low capacity
high affinity

36
Q

affinity

A

affinity describes the strength of the interaction between (usually two) molecules that bind together

37
Q

more protein bound drugs

A

penetrate tissues better than those that are highly protein bound

clearance of such drugs is also higher

38
Q

therapeutic index (Ti)

A

ratio of toxic concentration to therapeutic concentration

39
Q

Large TI

A

safer if does isnt accurate

40
Q

Narrow TI

A

higher risk of toxicity if does isnt accurate

41
Q

therapeutic range

A

dosage range or blood plasma or serum concentration usually expected to achieve the desired therapeutic effect

42
Q

what factors influence renal clearance of drug

A
  1. filtration
  2. proximal tubular secretion
  3. distal tubular reabsorption
43
Q

filtration

A

depends on molecule size
protein binding
integrity of glomerulus

44
Q

proximal tubular secretion

A

can cause an increase in the size of elimination rate constant (shorter 1/2 life)

45
Q

distal tubular reabsorption

A

ion trapping can occur for lipid soluble unionized drug

46
Q

First Order Kinetics

A

amount of drug eliminated in a set amount of time is proportional to the amount present in the body

ex. aspirin

47
Q

Zero Order Kinetics

A

amount of drug eleiminated in a set amount of time is independent of the amount present in the body

ex. alcohol/phenytoin

48
Q

Loading Dose equation

A

LD = (CVd)/(FS)

49
Q

LD

A

loading dose
mg

50
Q

C

A

concentration
mg/L

51
Q

Vd

A

volume of distribution
L

52
Q

F

A

bioavailaibility

(between 0-1)

53
Q

S

A

salt fraction

54
Q

LD quick calc

A

Vd*C

55
Q

How to estimate drug half life

A

look at drug concentration time plot and determine where drug concentration drops in half, then calc the time it took for that drop from the x axis

56
Q

how to estimate volume of distribution

A

????

57
Q

estimate the time required to reach steady-state for first order drugs

A

50% of drug is lost each half life

58
Q

If 30 unites are present at the end of 3 half lives, how much drug did you start with?

A

240 units

end units*(2^(#half life))

30*(2^3)

59
Q

receptor agonist

A

substances that mimic the effects of a compound already made in the body

stimulatory

increase normal effect

60
Q

receptor antagonist

A

substances that block the effects of a compound already made in the body

inhibitory

decrease normal effect

61
Q

partial agonist

A

stimulates some of the natural effect

62
Q

partial antagonist

A

inhibits some of the natural effect

63
Q

EC50

A

concentration of a drug that is necessary to cause half of the maximum possible effect

64
Q

higher EC50

A

higher potency

65
Q

lower EC50

A

lower potency

66
Q

higher maximum effect

A

higher efficacy

67
Q

lower maximum effect

A

lower efficacy

68
Q

potency

A

measure of a drug’s biological activity expressed in terms of the dose required to produce a pharmacological effect of given intensity

69
Q

efficacy

A

the ability of an intervention or drug to produce a desired effec

70
Q

drug tolerance

A

occurs slowly over time
does not reverse rapidly after withdrawal of drug

CHRONIC tolerance

think opioids

71
Q

drug tachyphylaxis

A

occurs rapidly
reverses rapidly after withdrawal of drug

ACCUTE tolerance

72
Q

reversible
(competitive)

A

drugs bind to receptor but can be kicked off by other drugs w/higher affinity

used receptors can recycle

73
Q

irreversible
(noncompetitive)

A

drugs bind to receptros and then receptor is degraded

new receptors must be created after drug binds
used receptors thrown away

Pharmacology (9 decks)

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