Theophylline pharmacokinetics in children, comparing sustained release spheres (Theo-Dur sprinkle) with elixir.

A new sustained release theophylline preparation (Theo-Dur Sprinkle, TDS) was given b.i.d. and a theophylline elixir t.i.d. to eight children with bronchial asthma, 4-10 years of age, in an open study with a randomized cross over design. The serum concentration curves of theophylline were compared. The individual theophylline dose was close to 20 mg/kg body weight per day. On day 3 of each regimen, blood samples were taken 11 times over 24 h. There were great differences between morning concentrations of theophylline, with a range from 0.9-10.7 mg/l in children given elixir, while corresponding values for children given TDS were 4.1-19.3 mg/l. Fluctuation during a dosing interval was 276% for elixir but only 54% in the case of TDS. The morning theophylline levels on two consecutive days did not differ significantly when the children were treated with TDS. The bioavailability of theophylline from TDS was 94% (range 54%-121%). Parents preferred TDS in seven of the eight cases. TDS showed satisfactory sustained release properties but the study confirmed the need for individually tailored dosage of theophylline based on monitoring of symptoms and serum concentrations.