A drug X was given continuous intravenous infusion at 1.6 mg/min. The clearance of the drug is 640 mL/min. With a half-life of 1.8 hours, what would be the steady state plasma concentration of drug?
(A) 0.002 mg/mL (B) 0.004 trig/mL (C) 2.88 mg/mL (D) 3.55 mg/mL
(A) Answer- A. 0.002 mg/mLCpss is directly propoional to the dose rate & inversely propoional to the clearance of drug.Cpss = Dose rate/clearanceDose rate= 1.6 mgiml; Clearance= 640 ml/minCpss = 1.61640 = 0.0025 mg/ml = 0.002 mg/ml