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Jason's GI Block > Advanced Pharmacokinetics > Flashcards

Advanced Pharmacokinetics Flashcards

1
Q

Acidic drugs and lipid solubility, which ones have good passage?

A

uncharged, lipid soluble, low pH

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2
Q

Basic drugs and lipid solubility, which ones have good passage?

A

uncharged, lipid soluble, high pH

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3
Q

How to treat aspirin overdose?

A

manipulate tubular reabsorption by administering NaHCO3 to make urine basic and make the acidic aspirin poorly soluble

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4
Q

Renal clearance depends on? 2 things

A

Renal blood flow

rate of elimination

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5
Q

what is drug metabolism AKA?

A

biotransformation

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6
Q

what is biotransformation? where does it mostly happen? why does it happen?

A

chemical change to a drug to a metabolite, happens in liver to increase water solubility for excretion

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7
Q

MEtabolite can be 4 things

A

active
nonactive
new activity - levo-dopa
toxic -epoxide

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8
Q

Phase I metabolism does what

A

creates chemical functional group like -OH, SH, COOH on the drug

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9
Q

why do you get drug side effects

A

Phase I metabolism reactions can alter CYP450 via inhibiting/enhancing

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10
Q

what happens in PHase II metabolism?

A

conjugating water soluble molecule to functional group, like adding sugar to bilirubin or morphine

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11
Q

Phase II products are nearly always what? 2 things

A

inactive

more water soluble

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12
Q

Renal clearance definition?

A

amount of blood from which drug is removed by kidneys per time

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13
Q

more drug in the blood, how does what affect clearance?

A

more effective the clearance

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14
Q

pathway of a drug in the body 6 things

A

administration
absorption
distribution
elimination(metabolism/excretion)

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15
Q

what is ADME?

A 
drugs to and from their site of action:   
absorption
distribution
metabolism
excretion
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16
Q

in first order kinetics, drugs are eliminated at a rate proportional to what?

A

concentration in the plasma

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17
Q

when do you get classic first order kinetics?

A

rapid IV administration and distribution

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18
Q

in first order kinetics, how is the drug eliminated?

A

exponentially via half-life

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19
Q

what does log10(conc) vs. time give you instead of (conc.) vs. time?

A

give you a gradient, easier to work with and can verify the exponential process

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20
Q

in a short term infusion, why does the concentration in the blood plateau?

A

as concentration of drug increases, the elimination also increases

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21
Q

if you stop infusion, what does the drug elimination curve look like?

A

first order kinetics, half-life decrease

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22
Q

Which peak is higher? IV bolus? short term IV infusion?

A

IV bolus

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23
Q

why is it good that the peak for IV infusion is not high?

A

good for drugs with small therepeutic windows

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24
Q

what is the steady state of IV infusion?

A

rate infusion = rate elimination

25
Q

what happens if you change infusion rate by double or half?

A

the concentration will change proportionally

26
Q

multiple dosing every hal-life give what in concentration in plasma

A

a two-fold variation in concentration

27
Q

how do you reach steady state faster in a long term IV infusion?

A

loading dose

28
Q

what factors determine volume of distribution?

A
  • if drug binds to plasma proteins (greater conc in plasma - VD is small)
  • if drugs binds to tissues/taken up by cells (VD is large)
29
Q

What is volume of distribution?

A

volume of body water in which a drug appears to be dissolved in after it has distributed throughout the body

30
Q

what do you have to take into account re: dosing for oral administration of drugs

A

first pass metabolism by liver, end up with reduced drug in system

31
Q

first order elimination curve, picture it in your head

A

peak not as high as IV

not all drug is absorbed

32
Q

what is bioavailability?

A

the amount of active drug that actually enters systemic circulation

33
Q

what are 2 things bioavailability is affected by?

A

how much drug absorbed
how much drug is metabolized via:
-first pass
-local metabolism (GI before liver)

34
Q

how to calculate bioavailability from graphs?

A

Areas under the curves

35
Q

2 complicating factors in pharmacokinetics

A 
unusual drug behaviour
interpatient variability (narrow therapeutic windows)
36
Q

what’s bad if bioavailability is low?

A

more sensitive to variability

37
Q

what’s bad if you have slow distribution

A

drug may be eliminated before it’s fully distributed to target areas

38
Q

what is zero order kinetics

A

drug saturates elimination processes, and makes elimination constant

39
Q

what is a drug reservoir? what can happen to drug?

A

sites where drug accumulates:
prolong
terminate
slow distribution

40
Q

Common drug reservoirs in the body: 3 places

A

Plasma proteins
cells
fat

41
Q

what is a bad if you rapid IV admin of slow distributing drug? how to compensate?

A

may exceed therapeutic window

loading doses to be broken down

42
Q

single dose drug with zero oder elimination a problem?

A

Nope

43
Q

what’s the problem with multiple dosing of zero order elimination drugs?

A

disproportionate increase in concentration because steady state is never reached

44
Q

2 examples of zero order elimination drugs?

A

aspirin

alcohol

45
Q

2 things that effects pharmacokinetics in the elderly and neonates

A

reduced
renal excretion
hepatic metabolism

46
Q

renal clearance of newborn is ___% of adult

A

20%

47
Q

How long until newborn renal clearance at adult levels?

A

1 week

48
Q

renal function decreases starting at what age? % at 50

% at 75?

A

20yrs
75% at 50
50% at 75

49
Q

liver metabolism in newborns are deficient how? how long until 100%?

A

can’t do phase II conjugation

6weeks

50
Q

why can’t you give morphine to mom when she’s in labour?

A

baby can’t metabolize morphine, no phase II conjugation could be born addicted to morphine…

51
Q

how is liver metabolism affected in elderly? consequence?

A

reduced CYP450

increased half life

52
Q

Drug-Drug interactions:
Pharmacodynamic
Pharmacokinetic

A

A affects B without affecting concentration

A modifies B concentration at receptor

53
Q

drug drug interactions, the affect drug needs to be what to be clinically important?

A

narrow therapeutic window

steep concentration-response curve

54
Q

pharmacokinetic drug-drug interactions interact where?

A 
ADME
absorption
distribution
metabolism
excretion
55
Q

pharmacokinetic drug-drug interactions affects absorption how?

A

gastric emptying rate (opiates)

formation of pooly absorbed complex in gut (calcium and tetracyclines)

56
Q

pharmacokinetic drug-drug interactions affects distribution how?

A

displacement from plasma protein binding sites leads to transient toxicity
altering target therapeutic range

57
Q

pharmacokinetic drug-drug interactions affects metabolism via induction of CYP450 can do what? 2 things

A

reduced half life

increased bioactivation

58
Q

pharmacokinetic drug-drug interactions affects metabolism via inhibition of CYP450 can do what?

A

increase half-life and plasma concentration

59
Q

pharmacokinetic drug-drug interactions affects excretion how? 3 things

A

alter:
protein binding
tubular secretion (probenecid olympics)
urine flow/pH (NaCO3 for aspirin overdose)

Jason's GI Block (32 decks)

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