Comparison of steady state serum theophylline concentrations in healthy volunteers after dosing with Euphyllin retard and PulmiDur.

In a randomized cross-over study, theophylline serum levels were compared over a 12-h dosing interval after repeated administration of Euphyllin retard and PulmiDur to 18 healthy male volunteers. Although both preparations are sustained-release formulations they differ in the systems used and in the state of hydration of theophylline. Two tablets each of Euphyllin retard or one tablet PulmiDur plus one tablet PulmiDur forte were administered in an identical dosing scheme always before food intake. The mean value curves of theophylline serum levels obtained at steady state clearly demonstrate the marked sustained-release properties of both preparations. The relative bioavailability of Euphyllin retard vs. PulmiDur calculated from the individual ratios of the dose adjusted AUCs was 96(83-111)%, results being given as geometric mean and 95% confidence limits. Hence Euphyllin retard is equivalent to PulmiDur with regard to the extent of absorption.