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16 Cards in this Set
- Front
- Back
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What part of the kidney brings free drug?
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Renal arteries
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What factors ↓ renal drug excretion?
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Age, pre-existing renal disease, enzyme deficiencies
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Define: clearance
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Volume of blood cleared of drug per unit time (CL) - dependent upon kidney
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Define: elimination
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Clearance predicts the rate of elimination in relation to drug concentration (occurs in kidneys, lungs, liver, blood, muscle)
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What drugs are zero order kinetics that we need to know?
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1. Phenytoin, 2. ethanol, 3. Aspirin
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Define: zero-order kinetics
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Constant amount of drug eliminated over time; thus its saturable -> capacity is limited; if dosing rate exceeds elimination capacity, steady state cannot be achieved
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What is first-order kinetics
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Dependent upon [drug] achieved; constant FRACTION of drug eliminated over time
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Equation for first-order kinetics
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Rate of elimination = Clearance * drug concentration
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What is the equation for half-life?
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0.7 * Vd/ CL
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How many half-lives to reach steady state?
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4-5 half-life
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How many half-lives to reach 90% of maximal dose?
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3.3 half lives
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What is the equation for loading dose?
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Loading dose = Vd * (Therapeutic concentration)
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Equation for rate of elimination? Dosing rate? Maintenance Dose?
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Rate of elimination = Clearance * (drug concentration); Dosing rate = Clearance * Therapeutic concentration; Maintenance Dose = Dosing rate/ (F) * Dosing interval
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Equation for clearance
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Clearance = Rate of elimination/Drug concentration = (mg/min)/ (mg/ml) = ml/min
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Equation for elimination
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Rate of elimination = Clearance *Drug Concentration = ml/min * mg/ml = mg/min
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Define: steady state?
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Drug input = drug output; NOTE: Time to reach steady-state is dependent on ELIMINATION half-life. It is independent on dose size and frequency of administration
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