PharmacoKinetics Flashcards

1
Q

Therapeutic Index :

Formula

A

LD50/ED50

Bad/Good

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2
Q

Smaller therapeutic index =

A

More LETHAL

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3
Q

MORE efficacy – curve goes

A

Up

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4
Q

MORE potency - curve goes

A

Left

EC50 less

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5
Q

QD

Quaque die

A

1 per day

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6
Q

BID

Bis in die

A

2 per day

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7
Q

TID

Ter in die

A

3x per day

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8
Q

QID

Quater in die

A

4x day

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9
Q

Q#h

A

Every # hours

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10
Q

P.r

A

Rectal

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11
Q

I.d.

A

Intradermal

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12
Q

P.o.

Per os

A

Oral

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13
Q

Infusion (continous) for Rx with

A

Short half life

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14
Q

Intermittent infusion (short durations at intervals) for Rx w/

A

Long half life

irritate veins

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15
Q

Pharmacokinetics

A

How Rx’s PLASMA CONCENTRATION changes over TIME

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16
Q

Drug IN

Concepts:

A
  • Bioavailability (F)
  • Starting concentration (C0), Dose (D)
  • Apparent volume of d (Vd)
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17
Q

DRUG OUT

Concepts

A
Vd
1 compartment:
  0-order kinetics
  1-order kinetics
     T1/2, Kel (elimination), Cl (clear)
      Css (steady state), MD/D*
2 compartment
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18
Q

Steady state needs

A

Fixed dose at fixed interval

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19
Q
Affect Co (starting conc)
(Drug in)
A

Absorption

Distribution

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20
Q

Affect t1/2

Drug out

A

Distribution
Metabolism - ELIMINATE
Excretion - ELIMINATE

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21
Q

Bioavailability (F) =

A
F = AUC oral/AUC iv
0 = F = 1

Fraction absorbed into plasma

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22
Q

Dose conversion (oral - iv)

Mg, mg/kg

A

Di.v. = F x Doral

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23
Q

Vd =

L\kg

A

Vd = Di.v./Co

FROM Co = Di.v. / Vd
Conc=Mass/vol

24
Q

Elimination constant (Kel) =

1/hr

A

Kel = .7 / t1/2

25
Q

Clearance (Clp) =

L/hr/kg

A

Clp = Kel x Vd

26
Q

Half life (t1/2) =

Hr , min

A

T1/2 = 0.7 x Vd / Clp

27
Q

Maintanence Dose (MDi.v.) =

mg/hr/kg

A

MDi.v. = Css x Clp

28
Q

Interval Dose (Di i.v.) =

Mg/kg

A

Di i.v. = MDi.v. X interval duration

29
Q

Loading dose (D*i.v.) =

Mg/kg

A

D* i.v. = Css x Vd

30
Q

Zero order =

A

Single compartment
Fixed rate
NOT concentration-dependent

31
Q

1st order =

A

Single compartment
Variable rate
Concentration-dependent

32
Q

2 compartment =

A

2 first-order decays
Two variable rates
Concentration-dependent

33
Q

IV administration , F =

A

1

34
Q

Why need F?

A

Dose conversion

Iv-oral, MD, D*

35
Q

Vd

Absolute vs. Relative

A

Absolute Vd = L
Relative Vd = L/kg

Absolute = Relative x patient mass (kg)

36
Q

What if Rx Vd&raquo_space;> body weight?

or LARGE Rx Vd

A

Rx residing in tissues

Long t1/2

37
Q

Plasma Vd

A

3L

38
Q

Nonvascular extracellular Vd

A

16 L

39
Q

Intracellular Vd =

A

23 L

40
Q

Low Vd =

A

Rx to plasma

Short t1/2

41
Q

Medium Vd =

A

Extracell +/- intracell
Extracell - out kidney
Intracell - metab liver

42
Q

When can combined compartments be treated as 1?

A

Distribution rate > elmination rate

Distribution quick

43
Q

Single compartment phases

A

Distribution

Elimination (determine t1/2)

44
Q

Zero order, single compartment example

A

PEA
Phenytoin
Ethanol
Aspirin

45
Q

Zero order kinetics - enzyme saturation?

A

YES

46
Q

First order -usually concetration BELOW

A

Km

…rate dependent on [drug]

47
Q

First order decay

A

Concentration drops 50% every half life

48
Q

Plasma clearance (Clp) assumes

A

Unit time smaller than t1/2

ABSOLUTE Vd

49
Q

Steady state achieved after ___ half lives

A

5

50
Q

90% steady state after __ half lives

A

3.3

51
Q

Dose interval vs. continuous infusion

A

More variation between doses, but same steady state

52
Q

Loading dose (D*) only used when half life is

A

LONG

53
Q

How to ID 2-compartment?

A

Distribution slower, elimination WAY slower

54
Q

High Vd = (metab)

A

Hepatic metab

55
Q

Low Vd = (metab)

A

Kidney metab