Comparative absorption of theophylline following multiple doses of a sustained-release formulation and an elixir in...

This multiple-dose, crossover study in 18 healthy adult men compared the oral absorption of theophylline from Theolair-SR sustained-release tablets (TSR) given two times a day with that from a reference elixir given four times a day. No difference in the extent of absorption of theophylline from either formulation was seen. At steady state (day 5), the ratio of the AUC for TSR over a 12-hour dosing interval to the AUC for the elixir over a six-hour dosing interval, was 0.944 +/- 0.191 (mean +/- SD). Thus the extent of theophylline absorption from TSR is equivalent to that from the reference elixir (P greater than 0.25). TSR has the advantage of allowing less frequent dosing intervals than are necessary for the elixir.