Basic Pharmacokinetic Principles Flashcards

1
Q

pharmacokinetics

A

the actions the body takes on a drug

can be defined in terms of volumes and clearances

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2
Q

pharmacodynamics (PD)

A

the action a drug has on the body

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3
Q

volume of distribution

A

that volume in which a substance/marker/drug appears to be homogeneously distributed (dissolved)

an apparent volume of distribution

volume of distribution = amount of substance/concentration

more accurately described as plasma equivalent apparent volume of distribution

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4
Q

the hydraulic model

A

can be used to compare to drug distribution int he body

  • water soluble substances travers aqueous channels between compartments

aqueous channels vary in size

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5
Q

Describe the body’s water distribution.

A
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6
Q

first law of pharmacokinetics

A

amount of drug in body = concentration * volume of distribution

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7
Q

clearance

A

a term used to describe the time-dependent movement of drug

includes intercompartmental clearance and elimination clearance

rate of elimination = clearance * concentration

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8
Q

intercompartmental clearance

A

describes the movement of drug between compartments

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9
Q

elimination clearance

A

describes the metabolic alteration or removal of drug from the blood/body

rate constant (k) = clearance (liters/min)/volume(liters)

time constant (minutes) = volume (liters)/clearance(liters/min)

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10
Q

elimination clearance rate constant

A

the fraction or percentage of the volume that is cleared per unit time (minutes)

T(1/2) = 0.693/k

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11
Q

elimination clearance time constant

A

the time it takes for about 63% of the volume to be cleared

95% of a substance is cleared in three time constants

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12
Q

extraction ration

A

extraction ratio = clearance/flow

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13
Q

renal clearance

A

that part of the volume of distribution from which a substance is irreversibly removed

creatinine clearance = (U x V)/P

U = concentration of creatinine in the urine

V = time measured collection of urine (urine production rate)

P = concentration of creatinine in the plasma

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14
Q

second law of pharmacokinetics

A

target (steady state) concentration = infusion rate/clearance

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15
Q

clearance vs. elimination rate

A

clearance is a physiologic process assumed not to change over the course of observation

elimination rate is constantly changing due to the concentration of the parent drug constantly decreasing as a result of drug being continuously eliminiated from the system

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