In children, the average pharmacokinetic parameters of theophylline are: k=0.15 hr-1 and Vd = 0.5 L/kg, while in adults k = 0.1 hr-1 and Vd= 0.5 L/kg. What is the steady state conc that will be achieved if a constant rate iv infusion of 1 mg/kg/hr is administered in both populations ? and what is the infusion rate required to achieve steady state conc of 15 mg/L in these two populations ?
Compared to adults, children require
higher theophylline infusion rate to
achieve the same steady state conc.
In children:
Cps.s.=
1 mg/kg/hr
0.15hr-1 0.5 L/kg
= 13.3 mg/L
In adults:
Cps.s.=
1 mg/kg/hr
0.1hr-1 0.5 L/kg
= 20 mg/L
In children:
K0 =
15 mg/L 0.15hr-1 0.5 L/kg =
= 1.125 mg /kg/hr
In adults:
K0 =
15 mg/L 0.1 hr-1 0.5 L/kg =
= 0.75 mg /kg/hr
