A patient is taking 800 mg fast-release theophylline tablet (F=1) every 12 hr (k=0.15hr-1, Vd =30L). The drug conc measured right after drug administration was above the therapeutic range and the conc measured just before drug administration was below the therapeutic range. Recommend an appropriate change. (Theophylline therapeutic range is 10-20 mg/L)
The average conc is within the
therapeutic range. The fluctuations in
the conc be reduced by using slow
release tablets or administration of
smaller doses more frequently.
Cpaverage ss=
(1) 800 mg
0.15 hr-1 x 30L x 12hr
= 14.8 mg/L
Administration of the same dose in the form of slow-release tablets should maintain drug conc within the therapeutic range throughout the dosing interval.
