Steady state q2

[shigella123]

Show your calculation please. I want to see other's explanation.

A patient with an arrhythmia is to receive lidocaine by constant IV infusion. The target plasma concentration is 3 mg/L. The pharmacokinetic parameters for lidocaine in the general population are Vd 70 L, CL 35 L/h, and t1/2 1.4 hours. An infusion is begun. The plasma concentration of lidocaine is measured 2.8 hours later and reported to be 1.5 mg/L. This indicates that the final steady state plasma concentration in this patient will be

A) 1.5 mg/L
B) 2.0 mg/L
C) 3.0 mg/L
D) 6.0 mg/L
E) Insufficient data to answer

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[Apoplexy__]

B. All you need from this is that at 2 half-lives of infusion, the concentration is 1.5 mg/L. 2 half-lives = 75% of steady state, so:
1.5 = x(.75)
x = 2.0

 

[shigella123]

Thank you!