PHA 5127 Case Study 5 Fall 2007 SET I: True or False T F 1: A one compartment model means that drug in the blood is in rapid equilibration with drug in extravascular tissues. T F 2: For a linear model, the rate constant for elimination is not proportional to the amount of drug remaining to be eliminated. T F 3: Clearance and volume of distribution are independent each other, but both of them are dependent of dose. T F 4: A drug with a linear protein binding has linear pharmacokinetics. T F 5: In a linear one-compartmental model, lower dose and lower volume of distribution result in a lower initial drug concentration after a single IV bolus. T F 6: In a linear one-compartmental model, any two concentration points in concentration-time profile can determine drug half-life after a single IV bolus. T F 7: Total clearance is always greater or equal to renal clearance. SET II: Jane, 5’8”, 35-year-old, is being treated with the new drug for an infection disease. Jane weights 64.4 kg. Cpcreat in Jane is 0.8 mg/dL Assume a Vd of 0.24 L/kg*(TBW), and clearance of this drug is equal to creatinine clearance, and this drug follows a linear one compartment model. 1. In order to achieve initial concentration 6 mg/L, please calculate this IV bolus dose. 2. Calculate half-life of this drug, and how many half-lives will it take to drop concentration from 6 mg/L to 750 µg/mL?SET III: Drug-Y is mainly eliminated by liver and kidney. Renal elimination is only by glomerula filtration. Mike with liver failure was given 70mg of this drug via IV bolus. Two plasma concentrations at 3 hours and 8 hours after dose were 1.31mg/L and 0.65mg/L, respectively. The plasma protein binding for the drug is 90%. Calculate the hepatic clearance and the volume of distribution of this drug in Mike? (Use 130ml/min for glomerula filtration rate). SET IV: The renal clearances, the fractions of unbound in plasma and the molecular weights of four drugs in a 75 kg subject are as follows: CLrenal (mL/min) fu MW A 20 0.5 500 B 0.10 0.5 200 C 20 0.1 800 D 50 0.9 100 Which of following statement is true? (GFR is 130 mL/min and urine flow is 1.5mL/min.) A: Drug A has renal secretion. B: Drug B has renal secretion. C: Drug C has renal secretion. D: Drug D has renal secretion. E: None of
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