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General Pharmacology > Drug Disposition III > Flashcards

Drug Disposition III Flashcards

2
Q

Important pharmacokinetic parameters: (5)

A 
Bioavailability	
Volume of distribution	
First order elimination rate constant	
Half-life	
Clearance
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3
Q

During time course of drug action, assume ____ concentrations are proportional concentrations at _____ tissue.

A

plasma target

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4
Q

Drug action models are especially useful when: (2)

A

when magnitude of therapeutic effect cannot be measured clinically therapeutic window is narrow

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5
Q

Pharmacokinetic parameters vary substantially in the population and can even change over time in a single patient. True or false?

A

true

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6
Q

Most drugs are eliminated this way:

A

first order drug elimination

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7
Q

Constant fraction of drug eliminated per unit time is ___ ____ drug elimination.

A

first order

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8
Q

fThe first order elimination rate constant, ____ is the fractional rate of drug elimination.

A

kE

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9
Q

What are the units for kE?

A

units of reciprocal time

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10
Q

How do you calculate kE given starting plasma concentration? For example, starting plasma concentration is 600 ng/ml.

A

starting plasma concentration * (1-kE) 480 ng/ml

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11
Q

The time required to reduce the plasma drug concentration by 50% is known as _____. What are the units?

A

half-life time

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12
Q

t1/2 is _________ proportional to kE.

A

inversely

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13
Q

Estimate the half life of the drug:

A

50% of y-axis, then 1/2 on x-axis in left direction and half in right direction. Subtract x(greater value) - x(lesser value) = seconds about 0.7

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14
Q

Calculate half life from Log Plasma Concentration versus time plot t1/2 =

A

-0.301/1

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15
Q

What determines duration of action of a single dose?

A

half-life

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16
Q

___-___ half-lives for a dose to be effectively eliminated

A

5-6

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17
Q

In ______ dosage schedules, determines time to reach a new steady state when rate of administration changes.

A

chronic

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18
Q

Together, half life with _____ __ _____, determines choice of dosage interval.

A

margin of safety

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19
Q

Half life is an _____ process.

A

exponential

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20
Q

Drug administration is ____ order and elimination is ____ order.

A

zero first Because taking the pill does not depend on plasma concentrations.

21
Q

What type of curve is this?

A

Plot of drug absorption and elimination Elimination rate exceeds absorption so curve peaks

22
Q

Rate of drug absorption can be affected by: (3)

A

route of administration blood flow slow-release preparations

23
Q

Slower absorption means (2)

A

Lower peak concentrations Longer duration of action

24
Q

______ plasma concentration is reached under: zero order drug administration first order drug elimination

A

Steady-state

25
Q

Most drugs given _____ every half life.

A

once

26
Q

____ _____ , (units of ___) is the volume of plasma from which drug is fully removed per unit time.

A

plasma clearance ml/min

27
Q

CLp = Σ _____organs

A

CL of all

28
Q

CLp equation:

A

rate of elimination plasma concentration

29
Q

KNOW What equation is this? CSS * CLp Concentration of steady state * clearance in plasma

A

Rate of Administration

30
Q

Half life has nothing to do with steady state. True or false? Clearance is 1.44 L/kg/h, and its half-life is 1.9 h. At what rate would you need to infuse morphine intravenously to achieve an effective steady state plasma concentration of 65 mg/L in a 70 kg man?

A

6.5 mg/hr

31
Q

Clearance (CL) is __________ to half life.

A

inversely proportional

32
Q

CL is dependent on Vd. True or false?

A

false independent If you rate of Vd is increased, it is much slower to clear.

33
Q

It takes__-___ half-lives to reach steady- state.

A

5-6

34
Q

KNOW Time to reach new CSS depends only on the ___

A

half life exponential

35
Q

What can occur is there is an altered clearance of drug, for example people with renal insufficiency?

A

cumulative poisoning

36
Q

Therapeutically it is better to reduce dosing rate because ____ ____ at steady state remains the same despite number of doses.

A

mean concentration

37
Q

Choice of dose interval depends on balance of the following: (4)

A

Drug half-life Size of therapeutic window Frequency/severity of adverse effects Convenience and patient compliance

38
Q

When is a loading dose needed? (2)

A

drugs with a long T rapid onset needed for emergency

39
Q

Total loading dose depends on: (3)

A

plasma concentration volume of distribution bioavailability Total loading dose=(concentration) (Vd) F

40
Q

Loading dose is ___ times maintenance dose.

A

2 like z pack

41
Q

Single loading dose followed by ______ maintenance doses.

A

smaller

42
Q

What is the major goals of drug monitoring and dose adjustment?

A

refine estimate of clearance refine estimate of bioavailability

43
Q

When do you sample when monitoring a drug? (2)

A

Allow long enough after dosing for distribution phase to be over Usually, best time is right before a scheduled dose

44
Q

When monitoring a drug it is important to know if the patient is in steady state with a drug. True or false?

A

true in order to get an accurate estimate of steady state

45
Q

Treat the patient, not just the number because: (2)

A

Therapeutic window may vary with individuals Knowledge of previous plasma concentrations is important

46
Q

Constant absolute amount of drug is eliminated per unit time is known as:

A

zero order kinetics of drug elimination

47
Q

Amount eliminated is independent of concentration of drug remaining at any given time is known as

A

zero order kinetics

48
Q

In zero order kinetics, it is possible to reach steady state. True or false?

A

false Can NEVER reach steady state!

General Pharmacology (24 decks)

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