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18 Cards in this Set
- Front
- Back
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What is the best way to plot drug concen & time?
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Log-concentration vs time (gives a straight line)
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What is pharmacokinetics (PCKN)?
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The study of the time course of absorption, distribution, metabolism, & excretion of drugs
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What is used to obtain data for PCKN?
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Body fluids (blood, plasma, serum, urine, feces, saliva)
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What is the only limitation for using body fluids to determine PCKN?
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Blood concen of a drug don't often accurately predict the pharm effect at the site of action
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What is model dependent analysis?
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The # of body compartments for a given drug is determined from the log concen vs time curve
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What are the sizes of body compartments?
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Can vary from 0.1 L/kg for a drug that distributes to extracell water compartment to >50L/kg for a lipophilic drug sequestered in body fat
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What does the rate of transfer b/w compartments for therapuetic drugs follow?
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Most are 1st order or linear kinetic processes; the rate of change of concen is proportional to the concen present @ a given time. PCKN is indepen of dose, & doesn't change clearance, vol distribution, or 1/2 life
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What are the charac of the small # of drugs that follow nonlinear absorption, distribution, or elimin?
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The rate of change in concen is not proportional to concen @ a given time, dose-dependent, PCKN parameters will change unpredicably, has a rate limiting step
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What is elimin half life?
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(t 1/2= 0.7/lambda n) The time required for the blood concen to dec by 1 half in the post-distributive/ absorptive phase
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What is the 1st order rate constant?
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(lambda n) The constant of proportionality in the 1st order process, which relates the rate of elimin to the concen in the body
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Describe the PCKN parameters of 1st order kinetics.
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Linear log C vs time graph, dose independent, constant 1/2 life, constant clearance, inc linear concen @ steady state
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Describe the PCKN parameters of non-linear kinetics.
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Dose-depentent, inc in 1/2 life unpredictable, dec unpredictible clearance, inc unpredictable concen @ steady state
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What is concentration steady state?
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Drug in=Drug out.The concen when the amt of drug admin replaces the amt of drug elimin (occurs w/ chronic dosing)
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What is volume of distribution?
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A quantitative measure of the extent of distribution of a drug out of the blood stream. Also acts as a proportionality constant b/w concen & amt of drug in body @ any given pt.
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What are the important volume terms?
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Vyn or Vd, Vc, & Vss
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What is Vyn?
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The apparent volume of distribution. Vd=Vc +Vp (the larger the # the greater the distribution out of blood)
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What is Vc?
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Volume of central compartment
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What is Vss?
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Volume of distribution @ steady state; the vol after equilibrim is achieved
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