A child is taking one 25mg prednisone tablet (F=1) every 12 hours for the treatment of an acute attack of bronchial asthma. Calculate the average s.s. prednisone plasma conc. (k=0.2hr-1 and Vd=40L). What will be the average s.s. prednisone conc if the patient takes tablets that are only 80% bioavailable?
Bioavailability
The drug product that has lower
bioavailability will achieve lower
steady state drug concentration.
Cpaverage ss=
(1) 25mg
0.2hr- 1 x 40L x 12hr
= 0.26 mg/L
Cpaverage ss=
(0.8) 25mg
0.2hr- 1 x 40L x 12hr
= 0.21 mg/L
The 20% lower bioavailability results in 20% lower steady state concentration.
