Pharmacokinetics Flashcards

1
Q

What three modifications encompass Phase I Biotransformation?

A

Oxidative, Reductive and Hydrolytic

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2
Q

What is the purpose of Phase I Biotransformation?

A

expose a functional group

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3
Q

What organelle are Cyt p450 enzymes located?

A

endoplasmic reticulum

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4
Q

What is the function of Phase II reactions?

A

make a compound for water soluble

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5
Q

The clearance of drug by the kidney depends on what three variables?

A

GFR

being bound to plasma proteins

pH or urine

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6
Q

What are the two mechanisms by which drugs can be excreted via the intestines?

A

secreted directly into bile

secreted by GI enterocytes

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7
Q

What is the equation for Volume of Distribution?

A

[blood]/[body]

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8
Q

What three types of drugs have large Vd’s?

A

lipophilic

non-ionizable

low binding to plasma proteins

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9
Q

What is zero order elimination?

A

capacity to clear drug is at saturation

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10
Q

What is first order elimination?

A

clearance system is not saturated

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11
Q

What is the equation for half life of drug?

A

(0.693)(Vd)/clearance

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12
Q

Drug will accumulate in the body if the dosing interval is shorter than how many half-lifes of the drug?

A

4 half-lifes

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13
Q

What is the equation for accumulation factor?

A

1/fraction lost in one dosing interval

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14
Q

What is bioavailability?

A

the amount of drug that reaches systemic circulation

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15
Q

What is the equation for extraction ratio?

A

clearane/flow

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16
Q

What is the therapeutic window?

A

[drug] between MEC and toxic effects

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17
Q

What is the equation for steady state concentration?

A

dosing rate / clearance

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18
Q

What is the definition of steady state concentration?

A

[drug] where elimination is equal to the bioavailability

19
Q

What is the equation for bioavailability?

A

f x (1-ER)

20
Q

Do cytochrome ezymes act more during Phase I or Phase II metabolism?

A

Phase I

21
Q

Is capacity limited essentially first-order or zero-order kinetics?

A

zero-order

22
Q

Is flow limited essentially first-order or zero-order kinetics?

A

first-order

23
Q

Is half-life variable for a drug that is processed by first-order or zero-order kinetics?

A

zero

24
Q

After how many 1/2 lifes will a drug be negligible?

A

4-5 half lifes

25
Q

What is steady state depedent on?

A

drug half life

26
Q

What is the Katzung definition of steady state?

A

condition where the average total amount of drug in the body does not change over time

27
Q

What is the mnemonic for drugs that follow zero-order kinetics?

A

P’s & WHEATS

28
Q

What do the P’s of P’s & WHEATS stand for?

A

phenytoin and phenylbutazone

29
Q

What does the W of P’s & WHEATS stand for?

A

warfarin

30
Q

What does the H of P’s & WHEATS stand for?

A

heparin

31
Q

What does the E of P’s & WHEATS stand for?

A

ethanol

32
Q

What does the A of P’s & WHEATS stand for?

A

aspirin

33
Q

What does the T of P’s & WHEATS stand for?

A

theophylline and Talbutamide

34
Q

What does the S of P’s & WHEATS stand for?

A

salicyclates

35
Q

What three groups are added to during Phase II Metabolism?

A

acetylation

sulfation

glucoronydation

36
Q

What is the equation for clearance?

A

elimination/[Drug]

37
Q

Which order of kinetics does capacity eliminated excretion follow?

A

zero-order

38
Q

Flow dependent elimination mimmics which order of elimination?

A

first-order

39
Q

Accumulation of drugs in the body will be detectable if dosing interval is shorter than how many half lives?

A

4

40
Q

What is the equation for loading dose?

A

(Vd)([Desired Concentration])/F

41
Q

What are the units for clearance?

A

mL/min/Kg

42
Q

What is the equation for Dosing Rate?

A

Clearance x Desired Concentration

43
Q

What is the equation for Dosing Rate-Oral?

A

Dosing Rate ss/ F-oral