Example:

The average daily dose of quinidine for the treatment of cardiac arrhythmia for a 70-kg adult patients is 400 mg every 8 hr (CLT= 20 L/hr, Vd = 2.7L/kg). What is the average steady state conc achieved with this regimen? Also, what will be the steady state conc if this average dose is administered to a patient who is only 40 kg and has the same CLT?

Vd
Smaller body weight means smaller
Vd. However the steady state
concentration is dependent only on
the dosing rate and the drug CLT.

Answer:

Cpaverage ss=

F D

CLT τ
Cpaverage ss=

(1) 400 mg

20 L/hr x 8 hr = 2.5 mg/L

The steady state concentration is dependent only on the dosing rate and the CLT

Vd